# Forum More Stuff Owner Builders Forum  House design

## manofaus

Just wondering when designing a house should you try to keep all the rooms 'to the foot' when making the size dimensions. Because this is how the material is supplied? 2.4, 2.7, 3.0, 3.6, 4.2, 4.8, 5.4, 6.0 etc....? Is this the best for material usage and minimise wastage? Or really when you add doors, windows etc its really just the ceiling sheets that would be maximised.... ?????

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## Master Splinter

Doesn't really matter that much.  If you optimise it for one material (say the wall framing) you'll find that it isn't quite right for the plasterboard or the bricks or the windows or the doors.  
Studs are on 450 centers, but many places sell timber on 300 increments, so you have to limit yourself to multiples of 900mm to maximise both.  Then you find that gyprock is only commonly stocked in lengths like 2400, 3000, 3600, 4200, 4800, and only one of these falls on a 900 multiple, so you will have a lot of 3600 rooms.   
Then a brick with mortar joint is 240mm, so 1200, 2400, 3600 and 4800 look like good measurements...but remember there is a 50mm gap between the frame and the wall so an outside corner to outside corner stretch will need a frame that is 100mm shorter, so you are going to waste framing.  And of course, all cut bricks will be taken out of a whole brick. 
Then you find that the local place sells (for example) so much 4800 gyprock it's cheaper to waste half a sheet than buy a smaller sheet.   
And the slab ends up being 20 mm bigger than expected, which throws all the careful calculation out, anyway!!!! 
600mm multiples are the nearest general purpose optimisation, in my opinion!

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## cherub65

Also if face brick is used for exterior its more important to use a brick rod to calculate lengths of walls.

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## zacnelson

Yeah definitely let the even ness of the brick courses be the standard, or else the exterior can look weird

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## jago

Truly, you should only be limited by your budget not the measurements.  
Measurements come in to it when access and manpower is an issue the bigger the item the more planning for access and to do the install  etc, so a large 6metre plasterboard may take longer to get in to the house and longer to put up so the potential saving in time on finishing is negated. A good builder will minimise wastage from off cuts with good product knowledge and planning of the build. 
I disagree with MS on the Gyprock you should only buy it in lots then you can negotiate the m2 for example 10mm wall boards at $4.10 per m2 no matter the size of board. I only had 1.44m2 wastage on a ceiling of 144m2 and these off cuts where used for blocking and packers elsewhere. 
There are lots of tried and true standards and calcs for quantitive surveying and costing, a lot of them on this site.

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## manofaus

thanks for the thoughts.

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## manofaus

darnnit.... Also need to think about projections when thinking of inside fit out.... 19mm architrave to 25mm dado....HAHA

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## jiggy

The only thing i would keep in mind is maximum timber lengths, its pretty difficult to source timbers larger than 6mtrs. !

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