# Forum Home Renovation Structural Renovation  Using F5 timber instead of MGP 10

## mullfitz

<hr style="color: rgb(255, 255, 255); background-color: rgb(255, 255, 255);" size="1">      On my plans all is states is high  F5 radia pine 90x45 for  all framing 
I am going to use MGP 10 90v45  for bottom plates and corners 
for noggins and structures I am using F5 90v35 
Does anyone see an issue with this 
The reason I am using f5 for structures is that it is 1/2 the price as MGP 10  
Cheers

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## Stan 101

90x35 f5 for noggins won't be a problem. Who specced the 90x45 F5?
What is it for load bearing or non loadbearing walls? 
Why on earth someone would spec 45mm timber in lieu of 35mm is bizarre. The only reason might be due to humidity but you would go for a greater grade such as MPG12 in 35mm before going to a 45mm section especially in 90mm. 
F5 tends to want to warp and bend if not kept in pristine condition before instrallation and still will want to wander after it is nailed and nogged. I'd get whoever specced your plans to ammend them to 35mm and then slap them into the 21st century, They are probably still using the old W codes before MGP came about. 
Without looking it up, I'm confident 90x35 P12 has a better MoE than 90x45 F5 and is much better in compression even with the sectional differneces.  
Cheers,

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## DvdHntr

F7 is the normal framing timber, F5 is still acceptable but not done. I would use 90x45-F7. If you want to save cost, the detail does say F5 so you could use the F5 for studs but I wouldn't advise it and in the long run the F7 will give you better results. 90x35-F5 for nogs is acceptable. Just make sure beams/girder trusses are supported by min double 90x45-F7 studs.

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## Pulse

F7 is not as common as it used to be:  HIA and Midcoast Timber 
Most pine framing I've bought recently has either been F5 (large discount pack lots from Eatons Mitre 10 in Cooranbong) or MGP10 from Bunnings.
MGP10 grading means each stick needs to be bent and the deflection recorded, I'd imagine it is more expensive than the visual F gradings. F5 won't warp or twist any more or less than MGP10 if it is properly seasoned from a recognised supplier. 
If the F5 is cheapest and that is what is specified, why are you using any MGP10 at all? It's just wasting money. If you do want to use MGP grades then get a copy of the Supplements to AS 1684.2 for F5 and MGP 10 and 12 and then substitute. That will let you use smaller sections eg 90x35 and larger spacings eg 600mm rather than 450mm, overall this saves money. 
I don't think using higher grades as a direct substitute will make your house last any longer since often if a stick of F5 pine is run through a MGP machine it will be graded as either MGP10 or MGP12. Doesn't mean the stick is any stronger, just graded as a higher strength. 
BTW Noggs don't have to be graded, 
Cheers
Pulse

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## DvdHntr

I don't trust MGP10, the grading system is seriously flawed and you can end up with the equivalent of non-structural grade. F5 is OK but I just think F7 is a more reliable grade and what has been used many times before on numerous houses and caused little issue.

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## Bedford

> I don't trust MGP10, the grading system is seriously flawed and you can end up with the equivalent of non-structural grade.

  Can you explain how and why this system is seriously flawed please?

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## Stan 101

> Can you explain how and why this system is seriously flawed please?

  I like to hear that expanation, too. I'd like to know how someone visually grading a stick of timber while it's moving on a conveyor belt would be more proficient than mechanical grading.  
F5 and MGP10 are similar in tension. MGP10 gets much better value in compression, though. MPG10 has similar compression values to F8. 
To think F7 is a common framing timber is strange. I don't think Carters even distribute F graded material at all in framing sizes. 
Also, will people stop perpetuating the myth that you put two studs under a girder. You bloody well put what is required. Whether that is one stud, 5 studs or you need to go to a steel post is based on the point load being applied to the support in question.  
cheers,

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## Gaza

a few years back they were going to change the grading of pine to a new system, all hell broke lose and that idea was dumped. 
MGP is needed for trusses as when the design the truss they know what stress's the timber can take, do a visual grade you could never tell how the timber will perform, trusses are designed down to the mm and the min, the old span tables for framing had a lot of excess in them to allow for any variation in timber quaility. 
my rule of thumb is for F7 use MGP12, for F5 use MGP10

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## Stan 101

> a few years back they were going to change the grading of pine to a new system, all hell broke lose and that idea was dumped.

  It is called SP grade and Hyne is the one pushing it. It is nearly across the line. All three truss nail plate suppliers have plugged in the use for SP ready to go as soon as it comes on line. Hyne want to use the SP grade as there is a lot of timber that just fails as MGP15 and must be dropped back to MGP12 and so on. There is nothing in the scope of the SP grade that notes the removal of MGP. MGP will stay if SP gets through. 
There was a lot of talk about SP grade at the two previous Frame Australia conferences. F grading of softwood is still hanging around over 10 years since the inception of MGP and it's not likely to be going anywhere soon. Especially with the amount of imported softwood from NZ, the pacific rim, and the two Americas. These imported timbers are usually regraded and stamped as 'F5 or greater' or 'F8 or greater' 
The biggest issue with removing the less stringent F visual grade is that smaller mills will need to outlay a lot of money to gear up for MGP or SP. Hyne have recently installed state of the art x-ray grading machinery at their Tuan plant with a view to minimising fall down of grade and readying for SP should it get across the line.   

> MGP is needed for trusses as when the design the truss they know what stress's the timber can take, do a visual grade you could never tell how the timber will perform,

  Have you a valid reference for that? That is simply untrue. All three truss software packages in Australia can and do use F grade timber in their databases. Not only do you choose the strength grade, you need to note the timber's joint group. If the timber passes the tests for it's particualr application as a member in the truss, it will be used if the timber is ticked on as 'usuable' in the databases.[/quote]     

> my rule of thumb is for F7 use MGP12, for F5 use MGP10

  This isn't flippant, it is a real question. Why not just design and do the take off with the correct product in the first place? 
cheers,

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## Gaza

yea good call about the timber coming in from NZ, what about all of COL oregon that gets used in stick frame roofs in sydney. got me stuffed how the enginer does not put a stop to it, 
Joint group is over looked by most people 10yrs back there was a shortage of pine framing with pre GST building boom, a heap of baltic pine came into Aus, only issue was frame and truss plants got caught with there pants down as it had a differnt joint group to radita, 10yrs on its you can buy gang nails to suit baltic. 
i dont design i build, i try to use what ever is spec, if i can not buy what it is spec we go to the closest alternat then have it approved by the engineer.

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## Stan 101

> 10yrs on its you can buy gang nails to suit baltic.

  Whoever has been telling you about the truss industry needs a fire extinguisher because their pants are on fire. The design of the timber connector mailplate has not changed design since the 1970s. You get a plate from the 70s and put it beside a nailplate manufactured today from the same manufacturer and they will be identical. 
You don't use a different type of nail plate for different joint groups.  You may or may not need to use a larger size nail plate depending on the truss and its application.You design the joint based on the timber strength group and the joint group and select the size of the plate based on the tooth count required to keep the joint together, and choose the thickness of the nail plate if shear in the joint is a factor. 
The Baltic that started coming in in big container numbers in about 1998 was generally treated as JD6 whereas most people plug in their slash and radiata as JD4 but it is safer offering it as JD5. This is a simple switch in the software databases. 
Redcotes Wholesalers have been bring in firs and other blonde timbers for some time. It is a lovely tight, dense grain, is good for JD5 and is quite stable. It often goes F8 easily. 
Cheers,

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## DvdHntr

I can't say too much due to political reasons but here goes. 
Explanation 
The grading of MGP is done on an average over 100 samples, so it is feasible that timber mills throw a few MGP 15 in with the MGP10 so they can allow what would be non-structural timber to be graded as MGP10 and sell what would otherwise be cheap almost useless boards. I inspected and was advised by a professional timber grader that some trusses were being made with this lower strength timber and the deflections in the truss were evident. The SP was meant to stop this but what they wanted to do was grade this timber as other materials were to the 5th percentile, which means on the bell curve the strength of the sample at the 5th percentile had to exceed the grading strength. The problem was mills who are big players in this industry didn't want to change and lose money so the rules were watered down and factors added to the calculation which I pointed out as many other probably did that it meant nothing would change. Don't buy MGP10 if you are relying on its stiffness (deflection), although F grade is visually graded that is better, unless you go to MGP12 or 15. F7 is the standard framing timber.

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## DvdHntr

> Whoever has been telling you about the truss industry needs a fire extinguisher because their pants are on fire. The design of the timber connector mailplate has not changed design since the 1970s. You get a plate from the 70s and put it beside a nailplate manufactured today from the same manufacturer and they will be identical.

  Basically, but I think you will find that the shape of the teeth has changed a little over the years but they may be closer today to the 70's than ones in the 90's. Double stud under girders is for multiple reasons. 
To make sure a stud is there, without saying double stud sometimes the framer will not put any.
The design of studs including axial shortening and lateral buckling is not something that should to attempted without the correct knowledge.
Girders are sometimes double trusses which means that the single stud is not directly under the whole of the load and the top plate (a timber on edge) is loaded. 
For the sake of a few sticks of timber, I would rather use double studs.

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