# Forum Home Renovation Structural Renovation  2.34m ceiling - Options?

## frasderp

My first post here everyone, be gentle! 
I have done quite a bit of reading on this and am still unsure on the best way to proceed. 
I have two full renovated rooms on the bottom floor of my Queenslander, however the ceiling heights come in at 2.34m, obviously below legal height. 
My thoughts now are -   I have seen some people possibly apply for relaxations to get these approved, possible/likely?Could I remove the ceiling and treat the floor above as the ceiling, leaving the joists exposed? I see there are different statements around ~50% of the ceiling must be above 2.4m etc? Do some inspectors accept this? 
Further to this, as this is my first home, what exactly is the process to applying for a room to be approved as habitable? 
Other ideas I toyed with were replacing joists with smaller options, but definitely getting into the more expensive territory... Thankyou!

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## phild01

This might be of interest: http://www.hpw.qld.gov.au/SiteCollec...s/3-06-088.pdf 
Might be noted that the document is in error when it says:
"Clause 3.8.2.2 specifies minimum ceilingheights of 2.400m for habitable rooms such as..." 
The code says 2.4m, not 2.400m and there is a difference.

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## ringtail

So did someone not raise the house enough ?  :Tongue:  Who has done the renno work ? Any plans or certification involved in all of this ? 
You don't need any approval for a room to be deemed habitable ( unless you rent it). Those rooms can be "storage " rooms. Heaps of people are in your situation and everyone knows the rooms will be used as bedrooms but technically they must be called or advertised as storage rooms. Look at all the flood properties. People have rebuilt and still enclosed or rebuilt rooms that were flooded. Even new houses built in flood zones have bedrooms ( sorry, "storage" ) rooms below flood level.

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## sol381

What he said.. I think you can call them alledged bedroom mate..6cm isnt that much .. you are allowed 24m for habitable rooms and 2.1 for non- habitable..why are you worried about it.. are you going to rent them out or concerned about resale down the track..  did you do the reno or did you buy the house like that..also how is 2.4 not 2.400.

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## Spottiswoode

Dig down some more? 
2.4 may not be 2.400 because 2.38 and 2.42 can be reported as 2.4 when rounded to the least significant figure. I used to 'get away' with this all the time in lab test results. When it is stated as 2.400 you can't round up 2.38 becuase it needs to be reported as 2.380. Anyway, moot point for the OP as 2.34 will never round up to 2.4.

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## phild01

> 2.4 may not be 2.400 because 2.38 and 2.42 can be reported as 2.4 when rounded to the least significant figure. I used to 'get away' with this all the time in lab test results. When it is stated as 2.400 you can't round up 2.38 becuase it needs to be reported as 2.380.

  Good explanation

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## sol381

most times its in mm anyway not metres so theres no confusion..

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## frasderp

Thanks for the replies guys. I bought it as it is. 
I don't have any info on the renovations as yet, but am trying to chase something down. 
phild -Thankyou for that, I saw that document, to be honest it prompted some of this thinking. 
Ringtail, I can't work it out! The upper floor has very high ceilings, so you wouldn't have missed a few cm on the bottom I'm sure! It may have been lifted prior to the legislation I'm not sure...   
The reason I'm concerned is if my situation changed for work for example, and I wanted to rent the property (or had to sell up quick?) It would make life easier if I could call them bedrooms at the end of the day... 
Back to my other question, is exposed joists an option?  
Thanks again for the help!

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## Optimus

Was it advertised as bedrooms when you bought it?

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## frasderp

> Was it advertised as bedrooms when you bought it?

   Yes, I was well aware of the situation. Currently used as a study anyhow. I do remind myself that there would be other buyers making the same 'consideration' I did  :Smilie:

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## toooldforthis

remeasure em.
get 2.35
round up
2.4
qed :2thumbsup:

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## OBBob

> remeasure em.
> get 2.35
> round up
> 2.4
> qed

  Yeah, there's a there's an old thread somewhere about inaccurate tape measures... go and find one.   :Biggrin:

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## sol381

whats a tape measure.. doesnt everyone use laser measurers now.

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## ringtail

> Thanks for the replies guys. I bought it as it is. 
> I don't have any info on the renovations as yet, but am trying to chase something down. 
> phild -Thankyou for that, I saw that document, to be honest it prompted some of this thinking. 
> Ringtail, I can't work it out! The upper floor has very high ceilings, so you wouldn't have missed a few cm on the bottom I'm sure! It may have been lifted prior to the legislation I'm not sure...   
> The reason I'm concerned is if my situation changed for work for example, and I wanted to rent the property (or had to sell up quick?) It would make life easier if I could call them bedrooms at the end of the day... 
> Back to my other question, is exposed joists an option?  
> Thanks again for the help!

  You'll have 2.7 or 3.0 ( 9 or 10 foot ) upstairs and I suspect it's the 8.5 mt height limit that has stuffed things up. Or someone cheaped out and didn't want to dig down 500 mm. Exposed joists is certainly going to get you closer but it depends on what has  been hidden by the gyprock ceiling. House raising can leave some pretty gnarly stuff to hide like big steel beams. Of course the plumber and sparky will have done all manner of ugliness in there too. Can you access the ceiling space at all ? If not it may be worth cutting  a hole to get your head and shoulders through to have a squiz. You may find some 300 mm deep PFC's have robbed the height you need. There are ways around this too but you need to see what's going on first.

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## r3nov8or

I reckon if you expose the joists above you will then be able to use the average of the measurements

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## sol381

not sure it works that way..usually measured to lowest protrusion not averaged out..best to check local council regs tho

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## phild01

> not sure it works that way..usually measured to lowest protrusion not averaged out..best to check local council regs tho

  Nothing was said about my beam to achieve a 2.39 ceiling height!

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## r3nov8or

I reckon averaging had something to do with that 'the Block' kitchen a few years ago when they had 2.1 and had to get to 2.4. Luckily I didn't watch it closely  :Smilie:    Could be a VIC thing

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## sol381

kitchen is deemed as non habitable.. can be 2.1m.. at least up here it is..again it depends on how the certifier feels. some are good , some not so much

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## phild01

Yep, kitchens are 2.1, a thing my certifier didn't realise :Rolleyes:

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## r3nov8or

Mmmmmaybe there was some below 2.1 and some at 2.4....? Anyway, moving on  :Smilie:  
frasderp, check out averaging in your area I reckon, or put a kitchenette in each room  :Smilie:

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## phild01

> Mmmmmaybe there was some below 2.1 and some at 2.4....? Anyway, moving on  
> frasderp, check out averaging in your area I reckon, or put a kitchenette in each room

  I only catch bits of the block (wish it would go away) but I now remember seeing that bit and thinking they got it wrong.

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## toooldforthis

last time I looked, a while ago, you could use averaging over here in Perth. handy on all those lean-to sleep outs.
not sure it works out tho cause I reckon we're all below average over here  :Confused:

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## sol381

if you have a flat ceiling then its measured off the lowest point.. plasterboard or ceiling joist.. If its raked then 2/3rds have to be above legal height..at least thats what one certifier told me..things are way too complicated these days. ah to be back building in the 80s and 90s..

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## ringtail

I'm pretty sure that a certain % of the room can be under height as long as it doesn't impede movement. Like boxing in a PFC giving 2.3 is fine in a habitable room provided it meets certain criteria. Too buggered to look for the details but they are in the BCA somewhere

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## phild01

I think one criteria is that it has good airflow and the room can still work in a free practical way.  The BCA has some deem to meet clause I believe.

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## Spottiswoode

If you are living there, it doesn't matter anyway, you are only taking about a few cm. if you are planning on renting it out, you don't need to describe the rooms as bedrooms, but the tenants can probably work it out for themselves. The market will set the rental rate for you and it's probably not worth the extra expense of reconfiguring to get a few $ extra rent. 
if it was significantly low (200mm or more) that's a different story.

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## r3nov8or

See clause e,i,B   
So if you were to create projections by exposing the joists you will easily have 2/3 over 2.4m

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## ringtail

Good work. Saves me the trouble of finding it  :Biggrin:

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## Bloss

> This might be of interest: 
> The code says 2.4m, not 2.400m and there is a difference.

  Que? What difference? 2.4m = 2.400m = 2400mm - adding a couple of zeroes after the decimal point does not alter the measure. 
And rounding up only works if no-one checks - I have seen one or two certifiers happy with such an approach, but most i know would see the 2.4m as a strict minimum except under the special situations that r2nov8or identified in the BCA extract. But at 65mm few would get a tape measure or measuring laser out to check. 
In any case Phild01's link is an excellent find and close to what you are describing. A bigger question is who did the renovations and why were they not approved before you purchasing the house. Or did you do them after purchase? In the example given in the PDF from Phild01 the height reduction came after all approvals had been sought and given - it was a function of difficulties faced as the renovation proceeded. 
In your case, it seems, the whole renovation has been done and only now is approval being sought (unless you have done them). If the renovation was before you bought it then you have some ground as the new and unwitting owner who only noticed the 64mm lower ceiling after you purchased the house and are now trying to make sure it is all approved. But my guess is that the sale contract would have mentioned unapproved renovations and you would have had to acknowledge that - thereby accepting the risks and consequences in the event that did not get approved. 
So really down to the local council and how hard they want to be. If the unapproved renovations/ conversion of the lower floor were not mentioned in the contract then you might have better claim for an exemption. The Council might make you work for it i.e.: go through an appeal process. 
But as ringtail says the reality is that this is only going to become a problem if you try to sell (and the contract raises the issue) or are renting the rooms out (as insurance then becomes and issue) and are required to declare the rooms as 'habitable. As he says there are plenty of sleep outs, garages and basements areas that are fitted out and used is 'living' space, but are still not 'habitable space' under the BCA. The BCA is about approvals for construction and intended use - they don't go around checking what the actual use is.

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## phild01

> Que? What difference? 2.4m = 2.400m = 2400mm - adding a couple of zeroes after the decimal point does not alter the measure.

   It is different as a measure.  An example might be when you need to cut something to be 1mm thick.  You end up with something close to 1mm and it is okay, for all intents and purposes it is 1mm but a machinist disagrees and declare it is fact say 1.152 mm thick.  Your unit of measure is whole mm whereas the machinist works in fractions of a whole number.  Your unit of measure would be catastrophic for the machinist so he declares he needs accuracy to 3 decimal places or whatever. 
The BCA has presented a number that, as a measure, is significant to 1 decimal place only, and that means the error can be 0.05m either way.  If they want better measuring accuracy then they would write it as either 2400mm or 2.400m.  As it happens, I believe they may have done this intentionally as other specified measures in the BCA are expressed in mm.  Because they say 2.4m, it then has a consequence that this measurement can be done with a tape measure that only has decimetres marked on it. That tape would not give 2.4 as equal to 2.400. 
It comes down to the accuracy in which a measure is expressed.

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## UseByDate

> It is different as a measure.  An example might be when you need to cut something to be 1mm thick.  You end up with something close to 1mm and it is okay, for all intents and purposes it is 1mm but a machinist disagrees and declare it is fact say 1.152 mm thick.  Your unit of measure is whole mm whereas the machinist works in fractions of a whole number.  Your unit of measure would be catastrophic for the machinist so he declares he needs accuracy to 3 decimal places or whatever. 
> The BCA has presented a number that, as a measure, is significant to 1 decimal place only, and that means the error can be 0.05m either way.  If they want better measuring accuracy then they would write it as either 2400mm or 2.400m.  As it happens, I believe they may have done this intentionally as other specified measures in the BCA are expressed in mm.  Because they say 2.4m, it then has a consequence that this measurement can be done with a tape measure that only has decimetres marked on it. That tape would not give 2.4 as equal to 2.400. 
> It comes down to the accuracy in which a measure is expressed.

  Phild01. You have asserted this rule in the past. Do you have any proof that it is valid? 
 You seem to be assuming a tolerance based on the number of digits following the decimal point. In what standard is this documented?
 In the following   Rounding of numbers
 you will see a rule that is normally applied to technical drawings.  
 Usually, rounding the limits is something that more often happens in quality assurance during incoming inspection of products.  In such cases, Interpretation of Limits rule from ASME Y14.5 declares limits are absolute.  For example, 12.25 MAX is the same as 12.2500000000000000 MAX.  If the feature measurement is 12.2540, that measurement should not be rounded to 12.25, as it is still out of tolerance because it exceeded 12.25.  
 ie rounding of dimensions may not change a dimension to a value outside of its limits. Note that in the document a MAX value example is used. The same applies to a MIN dimension. Ie 2.4m MIN is the same as 2.400000000000000m MIN.

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## Spottiswoode

> ie rounding of dimensions may not change a dimension to a value outside of its limits. Note that in the document a MAX value example is used. The same applies to a MIN dimension. Ie 2.4m MIN is the same as 2.400000000000000m MIN.

  Yes, but if you are taking it to one decimal place then 2.38m is equivalent (not equal) to 2.4 if rounded to 1 decimal place. hence 2.38 would be the 2.4m minimum, but not if it was expressed as 2.400m. If you need 3 decimal places the 2.38 example could accurately be anywhere between 2.375 and 2.384 which is less that 2.400m. 
It is a mathematical practice to measure to the least significant digit in your recorded measurement. If the BCA says minimum 2.400m then anything less than 2.3995m is not habitable. If the BCA say min 2.4m then 2.35 is the minimum habitable room height. It's all about how many decimals are used to determine the minimum measure. 
As it stands the measurements in the BCA extract by r3nov8or above are all to one decimal place. So 2.4 is the measure and therefore 2.35 is acceptable.

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## Bloss

mmm - a lovely discussion of mathematics, but I suspect most certifiers will not be convinced of any leeway or a plus or minus measure - I'd love you to point that out in the BCA. They will use their tape or an electronic measuring device and will look only at the 2400mm or the 2.4m mark on their device (which of course will have its own error factor as well as their own eyesight and/ or reading error!  :Smilie:  
They might make a judgement call if there is a variation, and that's simply a real life practice, but they would not accept a position that there is any authority to allow anything under exactly 2.4m or 2400mm. That's why there is an appeal process that allows an exemption to be sought. Anyway I'll be on my bike on this side issue.

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## Spottiswoode

I'm sure the BCA wasn't written in 10 minutes. The lawyers would have seen to that. Unless it says in another part of the document that all measurements written as to the nearest 0.1m will be read as being acceptable to the nearest 0.001m then you can argue as much as you like, and probably have trouble convincing some certifiers that 2.35 is the same as 2.4 because it rounds to 2.4 as the least significant figure. 2.4 is not always equal to 2.400. I am reasonably certain that you could appeal to 'someone' and get approval for 2.35m.

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## UseByDate

> Yes, but if you are taking it to one decimal place then 2.38m is equivalent (not equal) to 2.4 if rounded to 1 decimal place. hence 2.38 would be the 2.4m minimum, but not if it was expressed as 2.400m. If you need 3 decimal places the 2.38 example could accurately be anywhere between 2.375 and 2.384 which is less that 2.400m. 
> It is a mathematical practice to measure to the least significant digit in your recorded measurement. If the BCA says minimum 2.400m then anything less than 2.3995m is not habitable. If the BCA say min 2.4m then 2.35 is the minimum habitable room height. It's all about how many decimals are used to determine the minimum measure. 
> As it stands the measurements in the BCA extract by r3nov8or above are all to one decimal place. So 2.4 is the measure and therefore 2.35 is acceptable.

  The Standard (ASME) is saying that if you measure 2.35m you are not permitted to round up to 2.4m because 2.35m is below the minimum permitted ceiling height. Ie It is outside permitted limits which are absolute.

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## phild01

> Phild01. You have asserted this rule in the past. Do you have any proof that it is valid? 
>  You seem to be assuming a tolerance based on the number of digits following the decimal point. In what standard is this documented?
>  In the following   Rounding of numbers
>  you will see a rule that is normally applied to technical drawings.  
>  “Usually, rounding the limits is something that more often happens in quality assurance during incoming inspection of products.  In such cases, Interpretation of Limits rule from ASME Y14.5 declares limits are absolute.  For example, 12.25 MAX is the same as 12.2500000000000000 MAX.  If the feature measurement is 12.2540, that measurement should not be rounded to 12.25, as it is still out of tolerance because it exceeded 12.25.”  
>  ie rounding of dimensions may not change a dimension to a value outside of its limits. Note that in the document a MAX value example is used. The same applies to a MIN dimension. Ie 2.4m MIN is the same as 2.400000000000000m MIN.

  A rounded up number doesn't carry the accuracy of what it originally had. Expressions of measurement have significance in expression. It is common in scientific terms to include the significance. Numbers in measurement are approximations to their least significant digit. So 2.400m approximates to a measure significant to half a mm which is the limit of it's accuracy, 2.4m approximates to half of it's least significant digit being half a decimetre. Not a notion I am making up, it is a rather common understanding in measurement taking.   The BCA is a document of adherence and I believe any expression of measurement should be done in a proper technical way. I am happy for them to leave it as 2.4 as it leaves room for deem to satisfy ruling.  https://en.wikipedia.org/wiki/Significant_figures

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## phild01

> mmm - a lovely discussion of mathematics, but I suspect most certifiers will not be convinced of any leeway or a plus or minus measure - I'd love you to point that out in the BCA. They will use their tape or an electronic measuring device and will look only at the 2400mm or the 2.4m mark on their device (which of course will have its own error factor as well as their own eyesight and/ or reading error!  
> They might make a judgement call if there is a variation, and that's simply a real life practice, but they would not accept a position that there is any authority to allow anything under exactly 2.4m or 2400mm. That's why there is an appeal process that allows an exemption to be sought. Anyway I'll be on my bike on this side issue.

   I think a lot of certifiers need to go back to their technical books and read about measurement expression IMO
..and I did strike one with this very argument.

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## sol381

Bloody hell,, getting your place approved by a certifier is hard enough without going into sematics about a number.. the code says 2.4 or 2400 or whatever you like to call it.. there is no leeway thats it ..theres no rounding up or down. At least 2400mm not a micron less..although some certfiers are less picky than others and it would be up to them as to whether a room gets passed or not..

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## phild01

> The Standard (ASME) is saying that if you measure 2.35m you are not permitted to round up to 2.4m because 2.35m is below the minimum permitted ceiling height. Ie It is outside permitted limits which are absolute.

  Problem as I see is that 2.4 is the expressed minimum ceiling height; and something that is 2.35 or more satisfies that expression.

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## r3nov8or

> ...some certfiers are less picky than others and it would be up to them as to whether a room gets passed or not..

  _Some_ certifiers don't even carry a tape measure... (I've never found one that does. Maybe they only pull it out when they sense something isn't quite right...)

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## Spottiswoode

> The Standard (ASME) is saying that if you measure 2.35m you are not permitted to round up to 2.4m because 2.35m is below the minimum permitted ceiling height. Ie It is outside permitted limits which are absolute.

  Agree with you, but 2.35m when expressed to one decimal place, as in the standard, is 2.4m.

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## Spottiswoode

> _Some_ certifiers don't even carry a tape measure... (I've never found one that does. Maybe they only pull it out when they sense something isn't quite right...)

  There is probably a significant amount of this. If it feels too low, they are going to get out the measure. If not, and face it can you tell the difference of a few cm over 2.4m, then it's all good.

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## UseByDate

> A rounded up number doesn't carry the accuracy of what it originally had. Expressions of measurement have significance in expression. It is common in scientific terms to include the significance. Numbers in measurement are approximations to their least significant digit. So 2.400m approximates to a measure significant to half a mm which is the limit of it's accuracy, 2.4m approximates to half of it's least significant digit being half a decimetre. Not a notion I am making up, it is a rather common understanding in measurement taking.   The BCA is a document of adherence and I believe any expression of measurement should be done in a proper technical way. I am happy for them to leave it as 2.4 as it leaves room for deem to satisfy ruling.  https://en.wikipedia.org/wiki/Significant_figures

   I am aware of the concept of rounding numbers and number significance. What you have not provided is when you can use the convention and when you can't. I still am of the opinion that if a tolerance is explicitly stated then the use of the number of significant numbers to quantify a tolerance cannot be used. Usually tolerances are quoted as being plus and minus an amount added to the specified length (using the example of length) or as a minimum and maximum length. Now taking the example of the ceiling height specified as minimum of 2.4m. The tolerance is explicitly given as minimum of 2.4m and implied maximum of infinity.  Because the tolerance is given the use of the significant number convention cannot be used.   
 Below is a quote from https://en.wikipedia.org/wiki/Significant_figures
 The document you provided to me  
 “However, these conventions are not universally used, and it is often necessary to determine from context whether such trailing zeros are intended to be significant. If all else fails, the level of rounding can be specified explicitly. The abbreviation s.f. is sometimes used, for example "20 000 to 2 s.f." or "20 000 (2 sf)". Alternatively, the uncertainty can be stated separately and explicitly with a plus-minus sign, as in 20 000 ± 1%, so that significant-figures rules do not apply. This also allows specifying a precision in-between powers of ten (or whatever the base power of the numbering system is).” 
PS I believe the BCA (at least with the ceiling height specification) is done in a proper technical way. ie the tolerance is explicitly specified so there can be no doubt what is meant.

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## Bloss

> _Some_ certifiers don't even carry a tape measure... (I've never found one that does. Maybe they only pull it out when they sense something isn't quite right...)

  :WHS: - Most only measure if they sense an issue.

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## UseByDate

> Agree with you, but 2.35m when expressed to one decimal place, as in the standard, is 2.4m.

  1.You are rounding up and the Standard says you are not permitted. 
 2. You are not permitted to use significant-figures rules if the tolerance is explicitly specified. (and it is).

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## phild01

> if the tolerance is explicitly specified. (and it is).

  where is this?

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## OBBob

This discussion feels like we've been here before.

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## UseByDate

> where is this?

  Minimum 2.4m and maximum (implied) infinity. It is in the sentence specifying the ceiling height

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## phild01

This is getting circular, the BCA aren't shy of using mm but for this they made the number less precise..

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## UseByDate

> This is getting circular, the BCA aren't shy of using mm but for this they made the number less precise..

  If you don't use significant-figures rounding/tolerance rules 2.4m is just as precise as 2.4000000000m
The following document contains a definition of tolerance. Working with Dimensional Tolerances | Materials content from Machine Design 
 Its important to understand what tolerance is. ASME Y14.5M defines it as the total amount a specific dimension is permitted to vary. The tolerance is the difference between the maximum and minimum limits. 
 The minimum is 2.4m and the maximum is infinity. ie the Limits of the dimension are 2.4m and infinity. You are not permitted to apply significant-figures rounding/tolerance to Limits. If you did you would be specifying  a tolerance to a tolerance.

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## phild01

> If you don't use significant-figures rounding/tolerance rules 2.4m is just as precise as 2.4000000000m
> The following document contains a definition of tolerance. Working with Dimensional Tolerances | Materials content from Machine Design 
>  ”It’s important to understand what tolerance is. ASME Y14.5M defines it as “the total amount a specific dimension is permitted to vary. The tolerance is the difference between the maximum and minimum limits.” 
>  The minimum is 2.4m and the maximum is infinity. ie the Limits of the dimension are 2.4m and infinity. You are not permitted to apply significant-figures rounding/tolerance to Limits. If you did you would be specifying  a tolerance to a tolerance.

  I read the link, maybe it is just me, but I thought it was swayed towards what I am saying.  As I see it the implied tolerance for a stated figure of 2.4 is +/- 0.05. 
The link also says this in part:  "Always use tolerances. Always. Ambiguity is not the friend of the mechanical designer. If you leave a dimension without a tolerance, no one else will know the importance, or unimportance, of the dimension." 
"Dimensions without tolerances leave the acceptable limits open, and it’s not the manufacturer’s responsibility to determine what is acceptable."   
Here the tolerance is specifically stated:  (the BCA expression of a range isn't as specific as this is)  "If a part is measured to be 0.2502 using a dial micrometer or other device, and the part’s dimension is supposed to be 0.250 *+0.000over−0.002* the dimension is not rounded down to three decimal places; it is considered nonconforming."

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## UseByDate

> I read the link, maybe it is just me, but I thought it was swayed towards what I am saying.  As I see it the implied tolerance for a stated figure of 2.4 is +/- 0.05. 
> The link also says this in part:  "Always use tolerances. Always. Ambiguity is not the friend of the mechanical designer. If you leave a dimension without a tolerance, no one else will know the importance, or unimportance, of the dimension." 
> "Dimensions without tolerances leave the acceptable limits open, and its not the manufacturers responsibility to determine what is acceptable."   
> Here the tolerance is specifically stated:  (the BCA expression of a range isn't as specific as this is)  "If a part is measured to be 0.2502 using a dial micrometer or other device, and the parts dimension is supposed to be 0.250 *+0.000over−0.002* the dimension is not rounded down to three decimal places; it is considered nonconforming."

  Phild01
 No. The statement confirms what I say.  "If a part is measured to be 0.2502 using a dial micrometer or other device, and the parts dimension is supposed to be 0.250 *+0.000over−0.002* the dimension is not rounded down to three decimal places; it is considered nonconforming."  
 The statement is saying that if the measurement is above the maximum LIMIT of 0.250 (0.250 +0.000) then the part is considered nonconforming. (rounding of the measurement is not permitted)
 In the context of the BCA and ceiling height, the statement above is stating that if the measurement is below the ceiling height minimum LIMIT of 2.4m then the ceiling height is nonconforming. (rounding of the measurement is not permitted). Ie If the ceiling height measurement is say 2.35m it cannot be rounded up and the ceiling height is nonconforming to the requirement. 
 Maybe I am not good at explaining but I will try with a simple example and referring to a previous referenced document for confirmation. 
 Let us specify a ceiling height of say 5m with a tolerance of plus and minus 2m. The specification is stating that any ceiling height between 3m and 7m would satisfy the requirement. Ie the ceiling height has a minimum height LIMIT of 3m and a maximum height LIMIT of 7m. The important thing to remember is that the tolerance is applied to the specified ceiling height of 5m not to the resulting minimum and maximum height LIMITS. 
 Quote from previous referenced document.
 Usually, rounding the limits is something that more often happens in quality assurance during incoming inspection of products. In such cases, Interpretation of Limits rule from ASME Y14.5 declares *limits are absolute*. For example, 12.25 MAX is the same as 12.2500000000000000 MAX. If the feature measurement is 12.2540, that measurement should not be rounded to 12.25, as it is still out of tolerance because it exceeded 12.25.   
 Now if you accept the above argument that tolerances are not applied to LIMITS then all I have to prove is that the BCA is stating a ceiling height LIMIT and not the ceiling height.  
 The BCA uses the words not less than which is a short hand, plain English, way of saying that the ceiling height should be 2.4m minus zero plus infinity. Ie the LIMITS are a minimum of 2.4m and a maximum of infinity. If the BCA just said the ceiling height shall be 2.4m, and no tolerance is given, you would be free to use any rounding convention accepted by the building industry. 
 According to BCA Vol 2 part 3.8.2, ceiling heights must not be less than:  in a habitable     room excluding a kitchen - 2.4 m andin a kitchen -     2.1m andin a corridor or     passageway etc - 2.1m andin a bathroom,     shower room, laundry, sanitary compartment, pantry, storeroom,     garage, car parking area etc - 2.1m andin an attic, room     with a sloping ceiling or projection below ceiling line or     non-habitable room or similar - a height that does not unduly     interfere with the proper functioning of the room or space. More     than 50% of the ceiling space should be on average a minimum height.in a stairway - 2.0m measured vertically     above the nosing line. 
 Do you accept that tolerances are not applied to LIMITS?
 Do you accept that the BCA is quoting a ceiling height LIMIT?

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## Uncle Bob

Have a mirrored ceiling. That should make it look twice the height  :Biggrin:

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## phild01

> Do you accept that tolerances are not applied to LIMITS?
>  Do you accept that the BCA is quoting a ceiling height LIMIT?

  In the world of American mechanical engineers, I agree as you say as indicated in the link's example.

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## UseByDate

> In the world of American mechanical engineers, I agree as you say as indicated in the link's example.

   So, you are saying that if the ceiling height was specified in a BCA (Building Code of America) in the same way it is in the BCA  (Building Code of Australia) then an American engineer would not round a ceiling height measurement of 2.35m to 2.4m and claim compliance. 
 Do you believe an Australian engineer would?

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## Spottiswoode

Has been a fun discussion. I now have no idea which is correct, but coming from an engineering/laboratory background find it hard to not round to the accuracy of the specified significant figure. 2.35 is equivalent to 2.4, and I believe an Aussie engineer would apply rounding. The BCA does not say limit, it says minimum - does that mean there is any difference in the intention of the document?

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## r3nov8or

In practice it will depend on the inspector; firstly whether he thinks, hmmm, it needs to be measured, secondly what tolerance he (and his council area) is prepared to work to, thirdly how much trouble you've given him so far and fourthly whether he had an argument with the missus earlier that day

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## UseByDate

> Has been a fun discussion. I now have no idea which is correct, but coming from an engineering/laboratory background find it hard to not round to the accuracy of the specified significant figure. 2.35 is equivalent to 2.4, and I believe an Aussie engineer would apply rounding. The BCA does not say limit, it says minimum - does that mean there is any difference in the intention of the document?

   Glad you are still with us.
 Minimums  (minima) and maximums (maxima) are the limits of the range of acceptable dimensions. The word limit does not have to be used. In plain English not less than means the minimum. What do you think not less than  means?
 Another example might help.
 Let us assume that a company is building a piece of equipment. Within that equipment there are two parts. One of these parts has a hole in it and another part is a pin that has to fit through the hole.  Now the pin is specified as having a diameter of 2mm plus 0.4mm minus 0.4mm.
 So the pin diameter can range between 1.6mm and 2.4mm. Ie the diameter of the pin must not be greater than 2.4mm. The pins are manufactured and they have a diameter of 2.4mm which is within specification. Let us assume that the hole in the other part is specified to be not less that 2.4mm in diameter. The parts with the holes arrives on the bench of two inspectors. One of the inspectors is an American and the other an Australian. The American and Australian inspectors measure the holes and they are 2.35mm in diameter. The American obviously rejects the parts because the pins will not fit. Do you think that the Australian will accept the parts with the holes because he rounds up his measurement to 2.4mm even thought the pins won't fit through the hole?

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## r3nov8or

In the OP's case, I hope an inspector doesn't want him to fill his room with a 2.4m cube. That would be awkward (or just silly)

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## r3nov8or

> In the OP's case, I hope an inspector doesn't want him to fill his room with a 2.4m cube. That would be awkward (or just silly)

  ... but maybe he would say, "Well this is an old house and accounting for minor variances over the floor and ceiling you can use a 2.34m cube"

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## r3nov8or

I also once lost half a mark on a Maths exam because I answered "0" rather than "0.0" 
Go figure

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## Spottiswoode

> Glad you are still with us.
>  Minimums  (minima) and maximums (maxima) are the limits of the range of acceptable dimensions. The word “limit” does not have to be used. In plain English “not less than” means the minimum. What do you think “not less than”  means?

  I'll go back to my lab days when the specified minimum was 14, and the reporting requirement was nearest 0.1 and 13.5, 13.6, 13.7 etc were all acceptable. Maybe the building industry has a different interpretation, but it's the way my mind works  

> Another example might help.
>  Let us assume that a company is building a piece of equipment. Within that equipment there are two parts. One of these parts has a hole in it and another part is a pin that has to fit through the hole.  Now the pin is specified as having a diameter of 2mm plus 0.4mm minus 0.4mm.
>  So the pin diameter can range between 1.6mm and 2.4mm. Ie the diameter of the pin must not be greater than 2.4mm. The pins are manufactured and they have a diameter of 2.4mm which is within specification. Let us assume that the hole in the other part is specified to be not less that 2.4mm in diameter. The parts with the holes arrives on the bench of two inspectors. One of the inspectors is an American and the other an Australian. The American and Australian inspectors measure the holes and they are 2.35mm in diameter. The American obviously rejects the parts because the pins will not fit. Do you think that the Australian will accept the parts with the holes because he rounds up his measurement to 2.4mm even thought the pins won't fit through the hole?

  If a rounded measurement doesn't fit what you are manufacturing then you haven't specified the tolerances accurately enough. If I specify 2 +/-0.4 I would expect that the limit of measurement is 0.05mm, half the least significant figure. If 0.44 is too big I need to specify 0.40, or to a level that will be acceptable to me. 
dont get me wrong, I completely understand what you are saying, I am just applying my experience differently.

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## UseByDate

> I'll go back to my lab days when the specified minimum was 14, and the reporting requirement was nearest 0.1 and 13.5, 13.6, 13.7 etc were all acceptable. Maybe the building industry has a different interpretation, but it's the way my mind works 
> If a rounded measurement doesn't fit what you are manufacturing then you haven't specified the tolerances accurately enough. If I specify 2 +/-0.4 I would expect that the limit of measurement is 0.05mm, half the least significant figure. If 0.44 is too big I need to specify 0.40, or to a level that will be acceptable to me. 
> dont get me wrong, I completely understand what you are saying, I am just applying my experience differently.

  I also understand where you are coming from, but why is my method of specifying tolerances perfectly adequate for the American inspector and not for the Australian inspector?

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## Spottiswoode

> I also understand where you are coming from, but why is my method of specifying tolerances perfectly adequate for the American inspector and not for the Australian inspector?

  If American and Australian systems are different you will need to make adjustments. After all it is 2016 and the Americans are probably still converting between imperial and metric half the time which will royally screw things up..

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## UseByDate

> I'll go back to my lab days when the specified minimum was 14, and the reporting requirement was nearest 0.1 and 13.5, 13.6, 13.7 etc were all acceptable. Maybe the building industry has a different interpretation, but it's the way my mind works 
> If a rounded measurement doesn't fit what you are manufacturing then you haven't specified the tolerances accurately enough. If I specify 2 +/-0.4 I would expect that the limit of measurement is 0.05mm, half the least significant figure. If 0.44 is too big I need to specify 0.40, or to a level that will be acceptable to me. 
> dont get me wrong, I completely understand what you are saying, I am just applying my experience differently.

    My experience is different from yours. 
 I started in the engineering industry 52 years ago. (aerospace industry). Our inspection department (quality assurance) used what were known as go/nogo gauges to determine whether a component part dimension was within specification or not. If a hole diameter, for example, was being measured a tool with a cylinder machined to the minimum diameter acceptable on one end and a cylinder machined to the maximum diameter plus a smidgen, acceptable on the other. The tool was used by trying to insert the minimum end into the hole and if the hole met minimum specification the tool would enter the hole. If the hole was less than the minimum specification the tool would not enter the hole and then of course rejected. The maximum diameter was tested in the same way, but using the maximum end. Of course the maximum end must not enter the hole. Ie the minimum end goes and the maximum end nogoes. Note at no time is the hole measured in the conventional sense of actually having digits assigned to it. Simply put; if you have no digits you cannot round the number. 
 Over my career I have worked with engineers that were educated in the following countries. 
 Peru, USA, Canada, Australia, UK, Ireland, France, Italy, Portugal, Poland, Latvia, Czechoslovakia, Cyprus, Uganda, South Africa, Israel, India, Pakistan, China (Hong Kong). 
 Not one of the engineers objected to the method. Not one claimed the measurement system is not valid because there is no opportunity to round the measured dimension.

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## phild01

The 2.4m ceiling height regulation would seem to be based on preference rather than anything else. 
  Who will come to harm, or die because the habitable ceiling  height is less than 2400mm.  What studies show detriment of having a ceiling height less than 2400mm. As an example, when it comes to balustrades, the measure is far more specific like 865mm on a stair railing or 1000mm for a balcony rail. Someone might die if the measure was less specific than this, and therefore shows a need to strictly adhere to that measure or be culpable. 
I contend that the 2.4m height is a rounded number as a convenient expression of measurement.  We have a metric system and the intended ceiling height minimum was expressed loosely to the nearest decimetre for convenience, as evident by expressing it as 2.4m rather than 2400mm. Simply, variation hardly matters.  If we still had an imperial system then the arbitrary height would have been expressed as 8 feet! 
The 'intent' of the arbitrary value should also be the basis of what is considered satisfactory. 
I think the best reason for settling on 2.4m is so that plasterboard sheets conveniently fit.

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## ringtail

Dunno about anyone else but I find 2.4 bloody awful and oppressive. Ceiling fans are a definite hazard worth noting too. 2.7 should be the minimum IMO.

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## joynz

> The 2.4m ceiling height regulation would seem to be based on preference rather than anything else. 
>   Who will come to harm, or die because the habitable ceiling  height is less than 2400mm.  What studies show detriment of having a ceiling height less than 2400mm. As an example, when it comes to balustrades, the measure is far more specific like 865mm on a stair railing or 1000mm for a balcony rail. Someone might die if the measure was less specific than this, and therefore shows a need to strictly adhere to that measure or be culpable. 
> I contend that the 2.4m height is a rounded number as a convenient expression of measurement.  We have a metric system and the intended ceiling height minimum was expressed loosely to the nearest decimetre for convenience, as evident by expressing it as 2.4m rather than 2400mm. Simply, variation hardly matters.  If we still had an imperial system then the arbitrary height would have been expressed as 8 feet! 
> The 'intent' of the arbitrary value should also be the basis of what is considered satisfactory. 
> I think the best reason for settling on 2.4m is so that plasterboard sheets conveniently fit.

  In the end, what's important is getting the OK from the building surveyor.

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## sol381

You had to do it didnt you. You had to go waaaaay off topic.. I actually think the minimum should be 2.65.

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## phild01

> Dunno about anyone else but I find 2.4 bloody awful and oppressive. Ceiling fans are a definite hazard worth noting too. 2.7 should be the minimum IMO.

   I agree 2.7m should be the desired preference but sometimes difficult to achieve with some types of additions.

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## phild01

> You had to do it didnt you. You had to go waaaaay off topic.. I actually think the minimum should be 2.65.

   :Rofl5:

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## r3nov8or

2.44m, rounded down is OK

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## ringtail

> you had to do it didnt you. You had to go waaaaay off topic.. I actually think the minimum should be 2.65.

  Oops  :Biggrin:

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## Marc

> Glad you are still with us.
>  Minimums  (minima) and maximums (maxima) are the limits of the range of acceptable dimensions. The word “limit” does not have to be used. In plain English “not less than” means the minimum. What do you think “not less than”  means?
>  Another example might help.
>  Let us assume that a company is building a piece of equipment. Within that equipment there are two parts. One of these parts has a hole in it and another part is a pin that has to fit through the hole.  Now the pin is specified as having a diameter of 2mm plus 0.4mm minus 0.4mm.
>  So the pin diameter can range between 1.6mm and 2.4mm. Ie the diameter of the pin must not be greater than 2.4mm. The pins are manufactured and they have a diameter of 2.4mm which is within specification. Let us assume that the hole in the other part is specified to be not less that 2.4mm in diameter. The parts with the holes arrives on the bench of two inspectors. One of the inspectors is an American and the other an Australian. The American and Australian inspectors measure the holes and they are 2.35mm in diameter. The American obviously rejects the parts because the pins will not fit. Do you think that the Australian will accept the parts with the holes because he rounds up his measurement to 2.4mm even thought the pins won't fit through the hole?

  But a 2.4 pin will not fit in a 2.4 hole. 
Interesting debate. However ... you can not compare the tolerance in measuring an engineering part with measuring a ceiling in a building. And how is this hight to be measured? Using a laser gives fraction of mm, using a tape, you must bend the tape and guess by looking at the tape bent in the corner. or should you have a rod cut at 2.4 and if it does not fit it's non compliant? 
All very funny but it's not furniture!

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## Spottiswoode

> My experience is different from yours. 
>  I started in the engineering industry 52 years ago. (aerospace industry). Our inspection department (quality assurance) used what were known as “go/nogo” gauges to determine whether a component part dimension was within specification or not. If a hole diameter, for example, was being measured a tool with a cylinder machined to the minimum diameter acceptable on one end and a cylinder machined to the maximum diameter plus a smidgen, acceptable on the other. The tool was used by trying to insert the “minimum end” into the hole and if the hole met minimum specification the tool would enter the hole. If the hole was less than the minimum specification the tool would not enter the hole and then of course rejected. The maximum diameter was tested in the same way, but using the “maximum end”. Of course the “maximum end” must not enter the hole. Ie the minimum end “goes” and the maximum end “nogoes”. Note at no time is the hole measured in the conventional sense of actually having digits assigned to it. Simply put; if you have no digits you cannot round the number. 
>  Over my career I have worked with engineers that were educated in the following countries. 
>  Peru, USA, Canada, Australia, UK, Ireland, France, Italy, Portugal, Poland, Latvia, Czechoslovakia, Cyprus, Uganda, South Africa, Israel, India, Pakistan, China (Hong Kong). 
>  Not one of the engineers objected to the method. Not one claimed the measurement system is not valid because there is no opportunity to “round” the “measured” dimension.

   That's how we ended up with the crazy imperial system. No measurements to start with. How big is it? A foot. how big is a foot? As long as thus widget. How long is this other widget then? I dunno, must be a yard. How long is a yard? Fred thinks it is 3 feet, but John thinks it is half as tall as he is. The measure of accuracy wasn't that important early on, but now we have a universal metric system tolerances have come into play. 
i can still make a widget any size I like, but if I want consistent widgets I'll probably measure is and work out some tolerances. Maybe I'll use a length of steel with some holes in it, but I'll probably use a caliber of a suitable size.

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## UseByDate

> That's how we ended up with the crazy imperial system. No measurements to start with. How big is it? A foot. how big is a foot? As long as thus widget. How long is this other widget then? I dunno, must be a yard. How long is a yard? Fred thinks it is 3 feet, but John thinks it is half as tall as he is. The measure of accuracy wasn't that important early on, but now we have a universal metric system tolerances have come into play. 
> i can still make a widget any size I like, but if I want consistent widgets I'll probably measure is and work out some tolerances. Maybe I'll use a length of steel with some holes in it, but I'll probably use a caliber of a suitable size.

   I really don't understand your argument. All of the countries I cited have officially adopted the metric (SI) measurement standard except the USA where it is not mandatory. In practice most of the engineering industry in the USA uses the metric system. As a result of joining NATO even their military uses the metric system.

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## UseByDate

> But a 2.4 pin will not fit in a 2.4 hole. 
> Interesting debate. However ... you can not compare the tolerance in measuring an engineering part with measuring a ceiling in a building. And how is this hight to be measured? Using a laser gives fraction of mm, using a tape, you must bend the tape and guess by looking at the tape bent in the corner. or should you have a rod cut at 2.4 and if it does not fit it's non compliant? 
> All very funny but it's not furniture!

   Yes; I know, (trust you to spot that) but I have to keep my arguments fairly simple. I am sure you will agree that if a 2.4 pin won't fit a 2.4 hole then it is going to be even harder getting a 2.4 pin in a 2.35 hole.  
 Before I built my own house I learned what I could from tradesmen that I knew. Carpenters told me to build the frame height at 2.42m. The reason being that after the ceiling plasterboard was fitted the ceiling height would be 2.41m. The 1 centimetre was to accommodate the accuracy of the measurement. Ie the accuracy of the tape measure and the talent of the measurer. If a 2.41m ceiling cannot be measured to an accuracy of 1 centimetre then what hope have we?  
 As a general question to all those in the building trade. Do any commercial building companies build rooms with 2.35m ceiling heights and claim they are 2.4m?

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## UseByDate

> The 2.4m ceiling height regulation would seem to be based on preference rather than anything else. 
>   Who will come to harm, or die because the habitable ceiling  height is less than 2400mm.  What studies show detriment of having a ceiling height less than 2400mm. As an example, when it comes to balustrades, the measure is far more specific like 865mm on a stair railing or 1000mm for a balcony rail. Someone might die if the measure was less specific than this, and therefore shows a need to strictly adhere to that measure or be culpable. 
> I contend that the 2.4m height is a rounded number as a convenient expression of measurement.  We have a metric system and the intended ceiling height minimum was expressed loosely to the nearest decimetre for convenience, as evident by expressing it as 2.4m rather than 2400mm. Simply, variation hardly matters.  If we still had an imperial system then the arbitrary height would have been expressed as 8 feet! 
> The 'intent' of the arbitrary value should also be the basis of what is considered satisfactory. 
> I think the best reason for settling on 2.4m is so that plasterboard sheets conveniently fit.

  Phild01,
 I think it was the other way round. The plasterboards are 1.2m wide so that rooms with a minimum ceiling height of 2.4m can be efficiently built. Any less than 2.4m means cutting a lot of boards along their length.

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## phild01

> Phild01,
>  I think it was the other way round. The plasterboards are 1.2m wide so that rooms with a minimum ceiling height of 2.4m can be efficiently built. Any less than 2.4m means cutting a lot of boards along their length.

   I thought that was what I indicated! Two 1200mm sheets fit the dimension.

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## UseByDate

> I thought that was what I indicated! Two 1200mm sheets fit the dimension.

   Yes; but two boards will not fit 2.35m.

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## sol381

I remember doing houses in the 90s and some suppliers had precut studs at 2335mm.. that meant your external walls were 2440mm after top, bottom and ribbon plate. Internals were  just over 2400mm.. That allowed for 10mm plasterboard and 30mm left to play for floor coverings..existing renovations are of course a different matter..

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## phild01

> Yes; but two boards will not fit 2.35m.

  Clearly, why it is more convenient to have 2400, a point I already indicated!

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## Jon

> Phild01,
>  I think it was the other way round. The plasterboards are 1.2m wide so that rooms with a minimum ceiling height of 2.4m can be efficiently built. Any less than 2.4m means cutting a lot of boards along their length.

  I would have thought it was the other way round.  The sheets are 1.2m or 2.4m to suit the building standards.   
Sent from my GT-I9505 using Tapatalk

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## phild01

Not sure what you are getting at, sheet sizes for many things are set at 1.2m or 4ft for as long as I can remember and probably before codes were dreamt about.  It is the way we round things off and the way things were rounded off when we went metric. 
But why is this of significance, *nobody goes out of their way to build inconveniently* but sometimes there are impediments.  The pertinent point I have tried to make is - has it been shown that deviating away from 2400mm is harmful to a person.!?  People live in smaller spaces with no ill effects.  Why would there be so much concern over a small variation in headroom.

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## sol381

why would you want it any lower.. 2.4m is the minimum anyone would want..my place is 2700 and i doubt id go any lower if i moved..thats the ruling now and until some knucklehead sitting behind a desk changes it we are stuck with it..it would affect window heights and door heights if you went lower as the soffits are usually 2.1m, so 2.4 is absolute minimum you would want..not sure why everyone is getting worked up over this.

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## phild01

Agree, 2400 is okay but most would prefer more.  But if someone is happy to have 2350 due to a building impediment, then why say no.  If a purchaser is still happy to have 2350mm in all good knowledge then why say no.
I love high ceilings especially in a living space, but in bedrooms it just hardly matters.  The regs do allow for variation too, subject to a room serving it's given purpose without issue (according to what my certifer has stated to me).

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## r3nov8or

> Yes; but two boards will not fit 2.35m.

  The 2.34 was measured with ceiling plaster in place, so the 2 x 1.2 would have fit before the ceiling went on 
1.35 sheets are readily available to do 2.7 ceilings

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## Spottiswoode

> The 2.34 was measured with ceiling plaster in place, so the 2 x 1.2 would have fit before the ceiling went on 
> 1.35 sheets are readily available to do 2.7 ceilings

  I've had to cut some off the top of all the boards in my reno's upstairs. One 1200 and one 1350 is too tall, two 1200 is too short. 'tis a pain in the buttocks.

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## UseByDate

In summery (my argument with Phild01)
 The original argument was whether it is permissible to round up a measurement, that is below a dimension that is specified as being “not less than” or not. Phild01 claimed that is was permissible and I said it was not.
 I provided a Standard (used by the greatest economy on earth) which proved my argument. Phild01 has not provided any documented evidence for his position. In fact he provided the documentation that proved my position.
 I have also provided an example where rounding would result in a part being accepted in error.
 The words “not less than” is plain English that any engineer or layman or judge can understand. Phild01 has said that he believes that the dimension 2.4m used in the BCA is either a “technical error” or a sly way of permitting a minimum ceiling height of 2.35m. Why go to all that bother? If 2.35m was acceptable why not just say it in plain English?
 My way of handling the limits of specified dimensions works with the metric system, Imperial system, American Customary unit system and even the Klingon Customary units system. How would you round three quarters of an inch?
 My way of handling the limits of specified dimensions works with binary, octal, decimal hexadecimal and also no numbers. (Gauge example).
 The BCA actually states that the ceiling height must not  be less than 2.4m. It does not say that the “measured” height of the ceiling must not be less than 2.4m. There is a difference. Rounding a “measurement” does not cause the ceiling height to change. 
 At the end of the day thought, the BCA is a “fit for purpose” code. Ie if you were building a retirement home for dwarves then a ceiling height less than 2.4m would probably be acceptable. Of course when you came to sell, it might become problematical.   
 Phild01 please tell me if I have presented you argument unfairly. I might not have understood your position.

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## Marc

> As a general question to all those in the building trade. Do any commercial building companies build rooms with 2.35m ceiling heights and claim they are 2.4m?

  Definitely in Melbourne. Probably 2.2 and claim it to be 2.5  :Smilie:

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## Marc

> The BCA actually states that the ceiling height must not be less than 2.4m. It does not say that the “measured” height of the ceiling must not be less than 2.4m. There is a difference. Rounding a “measurement” does not cause the ceiling height to change.

  That is a logical fallacy. When the rule may well say that the ceiling must be not less than 2.4, the only way to verify it is by measuring it so the only valid argument is the method of measuring the said height and not what it is supposed to be. After all the measure will vary every time the instrument used is changed and will produce a different measure every time. 
If the ceiling is 0.01mm lower than 2.4 it is non compliant yet no one has an instrument to measure that difference so it is down to the instrument used or rather the allowable tolerance. 
In my opinion of course, minus or plus a thought or two ...  :Smilie:

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## phild01

> In summery (my argument with Phild01)
>  The original argument was whether it is permissible to round up a measurement, that is below a dimension that is specified as being “not less than” or not. Phild01 claimed that is was permissible and I said it was not.
>  I provided a Standard (used by the greatest economy on earth) which proved my argument. Phild01 has not provided any documented evidence for his position. In fact he provided the documentation that proved my position.
>  I have also provided an example where rounding would result in a part being accepted in error.
>  The words “not less than” is plain English that any engineer or layman or judge can understand. Phild01 has said that he believes that the dimension 2.4m used in the BCA is either a “technical error” or a sly way of permitting a minimum ceiling height of 2.35m. Why go to all that bother? If 2.35m was acceptable why not just say it in plain English?
>  My way of handling the limits of specified dimensions works with the metric system, Imperial system, American Customary unit system and even the Klingon Customary units system. How would you round three quarters of an inch?
>  My way of handling the limits of specified dimensions works with binary, octal, decimal hexadecimal and also no numbers. (Gauge example).
>  The BCA actually states that the ceiling height must not  be less than 2.4m. It does not say that the “measured” height of the ceiling must not be less than 2.4m. There is a difference. Rounding a “measurement” does not cause the ceiling height to change. 
>  At the end of the day thought, the BCA is a “fit for purpose” code. Ie if you were building a retirement home for dwarves then a ceiling height less than 2.4m would probably be acceptable. Of course when you came to sell, it might become problematical.   
>  Phild01 please tell me if I have presented you argument unfairly. I might not have understood your position.

  Useby, I understand your position on this and I might have made a mistake by introducing engineer measuring standard.  But I still am in absolute disagreement.  The code has intent and to some extent IMO it is being overlooked.  Your arguments relate to the consequences of accuracy for a given part to work and fit with it's intended purpose of a partner part.  A 1.55 rod won't fit into hole that is specified as 1.5, can correct me otherwise.
My main argument relates to why and the intent of specifying a ceiling as not less than 2.4m.  It is all a  matter of preference and next to nothing to do with science or accuracy.  It is a loosely derived figure based on how we generally relate to things and preference.  And I did mention that if it weren't for the metric system, we would be discussing a value of 8 feet.  That value is different and it just doesn't matter.
So according to the way you say we should interpret the value of 2.4m is based on an argument that it's purpose is so that things will fit inside it.  How much furniture exceeds a height of over 2m.  I really can't think of much that requires a height of 2.4m so maybe the standard you wish to apply here has no relevance for it's intent.
All we need to satisfy is that the room height is fit for purpose, has proper ventilation and window size, and satisfies the intent of the code.. Nothing else is of concern other that we don't have grumpy builders because their sheets of plasterboard didn't fit without modification.
If the BCA wants mm accuracy then they should state the value as 2400mm.  That value has intentional accuracy in the same way we see a house plan.

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## joynz

> Useby, I understand your position on this and I might have made a mistake by introducing engineer measuring standard.  But I still am in absolute disagreement.  The code has intent and to some extent IMO it is being overlooked.  Your arguments relate to the consequences of accuracy for a given part to work and fit with it's intended purpose of a partner part.  A 1.55 rod won't fit into hole that is specified as 1.5, can correct me otherwise.
> My main argument relates to why and the intent of specifying a ceiling as not less than 2.4m.  It is all a  matter of preference and next to nothing to do with science or accuracy.  It is a loosely derived figure based on how we generally relate to things and preference.  And I did mention that if it weren't for the metric system, we would be discussing a value of 8 feet.  That value is different and it just doesn't matter.
> So according to the way you say we should interpret the value of 2.4m is based on an argument that it's purpose is so that things will fit inside it.  How much furniture exceeds a height of over 2m.  I really can't think of much that requires a height of 2.4m so maybe the standard you wish to apply here has no relevance for it's intent.
> All we need to satisfy is that the room height is fit for purpose, has proper ventilation and window size, and satisfies the intent of the code.. Nothing else is of concern other that we don't have grumpy builders because their sheets of plasterboard didn't fit without modification.
> If the BCA wants mm accuracy then they should state the value as 2400mm.  That value has intentional accuracy in the same way we see a house plan.

  Hi Phil 
Are you saying that a building inspector / surveyor will OK a ceiling height of 2.35?

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## phild01

> Hi Phil 
> Are you saying that a building inspector / surveyor will OK a ceiling height of 2.35?

   Don't know, but suspect it will cause a problem for many a certifier.  Mine is fine with 10 or 20mm.
Let's look at what it says, finished floor level from memory and AFAIK that supposedly includes floor coverings.  I would contend that it doesn't include loose floor coverings.

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## r3nov8or

I wonder if this statement in the BCA creates enough flexibility to make 2.34m 'OK'

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## phild01

> I wonder if this statement in the BCA creates enough flexibility to make 2.34m 'OK'

   That might be the section up the back I was trying to have reference to earlier - performance based criteria.  My certifier mentioned it to me.

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## Spottiswoode

THe OP has probably long left the building, but if he were to make the room look tall, ie no ceiling fan, short furniture, light colours and perhaps some vertical stripes, light fittings that don't protrude down much etc he is unlikely to find someone getting a measuring tape out to check.

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## UseByDate

> That is a logical fallacy. When the rule may well say that the ceiling must be not less than 2.4, the only way to verify it is by measuring it so the only valid argument is the method of measuring the said height and not what it is supposed to be. After all the measure will vary every time the instrument used is changed and will produce a different measure every time. 
> If the ceiling is 0.01mm lower than 2.4 it is non compliant yet no one has an instrument to measure that difference so it is down to the instrument used or rather the allowable tolerance. 
> In my opinion of course, minus or plus a thought or two ...

   Marc
 I disagree. It is not a logical fallacy. You don't have to measure the ceiling height to determine if it is not less than 2.4m. You can use a 2.4m stick as you have mentioned before. The stick has to be measured, but not the ceiling height. If the stick can be placed in the room, vertically between the floor and the ceiling, then the height is compliant. Builders are smart. They don't build right up to the acceptable limits of a dimension. Just by building the ceiling height of 2.41m (or 2.43 if the floor finish is 2 centimetres thick) they can be 100% certain that the height is compliant. (unless the carpenter building the frame is totally incompetent.) Anybody who builds right up to the limits of what is acceptable is just asking for trouble.
 I built my house and I can easily ascertain that the ceiling height is not less than 2.4m without measuring the ceiling height. I don't even have to know what the ceiling height is. All I have to know is that it is not less than 2.4m.

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## r3nov8or

> Marc
>  ...You can use a 2.4m stick as you have mentioned before. ...

  But don't use a thick stick as it's diagonal will be notably more than 2.4m  :Smilie:

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## phild01

and where shall the official 2.4m stick be held...Paris?

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## Marc

> Marc
>  I disagree. It is not a logical fallacy. You don't have to measure the ceiling height to determine if it is “not less than” 2.4m. You can use a 2.4m stick as you have mentioned before. The stick has to be measured, but not the ceiling height. If the stick can be placed in the room, vertically between the floor and the ceiling, then the height is compliant. Builders are smart. They don't build right up to the acceptable limits of a dimension. Just by building the ceiling height of 2.41m (or 2.43 if the floor finish is 2 centimetres thick) they can be 100% certain that the height is compliant. (unless the carpenter building the frame is totally incompetent.) Anybody who builds right up to the limits of what is acceptable is just asking for trouble.
>  I built my house and I can easily ascertain that the ceiling height is “not less than” 2.4m without “measuring” the ceiling height. I don't even have to know what the ceiling height is. All I have to know is that it is “not less than” 2.4m.

  It is a logical fallacy because there are no absolutes. You can not say like the corrupt senator in "The Shooter" ... "The truth is what I say it is"... the measure given is 2.4 and not lower. Sure ... now how do you determine if it is lower? You must support your claim that it is lower and you can only do so by measuring and when it comes to measuring by comparison with a standard instrument you must define the allowable error, so again, it comes down to tolerance as with any case of measuring. A stick may well be acceptable if it has rounded ends and the radius of the curvature is less than 2.4m ... Is there going to be the need to store the stick in some safe place? Who is to manufacture the stick? Measured with a Magnetometer? 
or it may be the case of using a tape as for 99% of cases ... or a laser? I love lasers. I have two Bosh models one gives me only mmm the other gives me fraction of mm. Which one should I use?  
I know this is just all academic, but it is good to stimulate the brain and think laterally.

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## UseByDate

> But don't use a thick stick as it's diagonal will be notably more than 2.4m

   But if it is longer than 2.4m and still fits the ceiling is not less than 2.4m and so complies. Bigger is better. :Smilie:

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## UseByDate

> and where shall the official 2.4m stick be held...Paris?

  I have got one in my shed  :Smilie:

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## UseByDate

> It is a logical fallacy because there are no absolutes. You can not say like the corrupt senator in "The Shooter" ... "The truth is what I say it is"... the measure given is 2.4 and not lower. Sure ... now how do you determine if it is lower? You must support your claim that it is lower and you can only do so by measuring and when it comes to measuring by comparison with a standard instrument you must define the allowable error, so again, it comes down to tolerance as with any case of measuring. A stick may well be acceptable if it has rounded ends and the radius of the curvature is less than 2.4m ... Is there going to be the need to store the stick in some safe place? Who is to manufacture the stick? Measured with a Magnetometer? 
> or it may be the case of using a tape as for 99% of cases ... or a laser? I love lasers. I have two Bosh models one gives me only mmm the other gives me fraction of mm. Which one should I use?  
> I know this is just all academic, but it is good to stimulate the brain and think laterally.

   OK Another example. You say that in order to establish that the ceiling height complies you have to measure the ceiling height. I say you don't.
 Certifier to me What height are the ceilings?
 Me  I don't know. I have not measured the ceiling height
 Certifier Are they less than 2.4m?
 Me No
 Certifier how do you know that
 Me I fitted the ceiling plasterboard (10mm) and then fitted two 1.2m gyprock plasterboards to the wall and there is a big gap between the the bottom board and the floor (much larger than the gyprock manufacturing tolerance).
 Certifier OK the ceiling height is not less than 2.4m and complies. 
 Question 1. Was the ceiling height measured.(I say no).
 Question 2. If the ceiling height was measured (as you say so)
 2a. Do I know the ceiling height? (clue: I don't).
 2b. Does the Certifier know the ceiling height? (clue: he does not)
 2c. Do you know the ceiling height?
 2d. Does anyone know the ceiling height? 
 How can you claim that the ceiling height was measured when no one knows what it is?

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## r3nov8or

I don't think that conversation happened in the OP's case... 
Or maybe it did and the certifier just believed it... Likely?

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## Marc

Is that the certifier from the bizarro world? 
This seems to me like a more likely scenario:
Are the ceiling lower than 2.4?
No.
How do you know?
I measured it.
What did you use?
My Bosch Laser, do you want to see.
Sure.
Here it is, look, 2.400
I see ... however your instrument has an error of +- 1mm so your ceiling is actually 2.399.5 / 2.400,5 so there is a 50% chance that it is non compliant ... FAIL ... come back ... next year! (the soup nazi)

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## phild01

> Is that the certifier from the bizarro world? 
> This seems to me like a more likely scenario:
> Are the ceiling lower than 2.4?
> No.
> How do you know?
> I measured it.
> What did you use?
> My Bosch Laser, do you want to see.
> Sure.
> ...

   Tell him to look up the back of his book for performance deem to satisfy :Biggrin:

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## UseByDate

> Is that the certifier from the bizarro world? 
> This seems to me like a more likely scenario:
> Are the ceiling lower than 2.4?
> No.
> How do you know?
> I measured it.
> What did you use?
> My Bosch Laser, do you want to see.
> Sure.
> ...

   No Marc. He said he was from Sydney. His name was Jimmy and he only just made our appointment. He mentioned something about a train strike. Luckily he did manage to catch the last train out.
 Your more likely scenario could not have happened.
 I don't have a Bosch laser. Remember I use a stick. I am strictly old school.    :Fingerscrossed:

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## Sir Stinkalot

> Is that the certifier from the bizarro world?)

  I recently had a council certifier out to check the pool fencing. Internally we have louvered windows that open onto the pool enclosure. As well as the glazing needing to be secure with a pin they also need a restriction fitted so the gap doesn't exceed the maximum opening. 
Anyway we are standing looking at the opening. He said it looks a little larger than the standards allow. Then he asks if I have a tape measure to test it! Thinking this was odd I let it past and kept talking. Then he asks again if I have a tape measure. Off I go a d find my tape measure and sure enough the opening was 10mm larger. The window fabricators hadn't fitted the restriction device yet. 
Now I'm not expecting him to rock up with his 2.4m ceiling height stick but his own tape measure would have been good form. He also had a work experience kid with him!

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## Offradar

Half of my house is 2200. No giants live here, though  :Smilie:

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