We are building a new home and I want some guidance on recommendations for design creating minimal wastage and maximum efficiency for the builders.
For example. Are room sizes best divisible by 4 since sheetrock is usually 4 x 8. Same way with plywood sheets. Or does this even matter?
If your objective is to optimize the product you receive (the completed house) vs the cost you pay for it by sizing to use full sheets of material -- forget it. The cost of all materials combined doesn't strongly dominate the cost of the project; they'll often sum to around half of the project cost. The panelized materials such as plywood or OSB sheathing, subfloor, and roof deck, and the drywall used throughout, are a small fraction of the project cost. Sizing the project to use whole sheets might literally save dollars or even tens of dollars per room. Other materials such as paint and concrete effectively come in bulk. Still others like electrical wire, drywall joint compound, or roofing shingles can't be reasonably estimated to ensure optimal use of each roll or box anyway. Basically the only thing where standard sizing matters is height: spec most of your rooms to have nominal 8 foot or 9 foot ceilings so that the builder can use off-the-shelf 92-5/8 or 104-5/8 studs. That makes the walls just the right height to fit 4 foot wide drywall (or 4-1/2 foot drywall in the case of 9 foot ceilings). The length of the wall really doesn't matter -- the drywall contractor will use 8, 10, or even 12 foot long panels as he sees fit. Small scraps have a way of being used above doorways or for casing window and passage openings.
A builder will quickly realize that your well-intentioned effort to optimize material usage will actually increase his labor cost; the net savings will be zero (or even negative). On the other hand, if your motivation is to optimize the materials as an eco-friendly or resource/footprint minimization measure, then you may not mind spending extra on the labor to achieve that goal.
I'd suggest that you not even think about efficiency for the builders, but rather think about efficiency for the life of the building -- its lifetime operating cost. Consider whether you want to incorporate passive solar design ideas which can reduce your heating and cooling needs (and can reduce the up-front cost of the corresponding equipment, too). Consider the advantages (or lack thereof) of specifying upgraded doors or windows. Consider whether to require insulation under your concrete and whether to upgrade the materials and methods for insulating the walls and attic. Consider future-proofing by installing a thoughtful system of conduits at least for low-voltage electronics, and maybe even for your mains wiring.
In summary: builders are much better at optimizing than a homeowner or even an architect could hope to be. Let them look after that, and expend your own limited design time and effort on higher-level things.
Drywall/subfloor has to be staggered. So boom you can't make a room that fixes that. Also drywall has depth meaning is your room going to be 12 feet or 12 feet and 1 inch?
I have a 5'3" drywall wizard that does a 1000 square feet (including ceiling with lights) in a day easy. He uses a knife and a string and every once in a while a straight edge that looks like a big yardstick. He has a buddy that goes behind him after he gets 4-5 screws in on each sheet to secure and his buddy can't keep up - to the point where he goes out in the backyard and kicks a soccer ball around during lunch while buddy catches up. He does ceilings by himself - even 12 foot sheets I kid you not. My point is, you would be saving him 10 mins max if you laid it out perfectly.
Think about how much extra time an architect and you would have to spend to do this to get it exactly right (and shit happens on site and if one person mismeasures anything perfection could be a 1/2" off). You also have corners that have to be doubled for drywall and so on... You aren't really saving anything on materials - completely negligible. I would almost want to see this tried because I think there would be more waste than normal - because if you designed it "perfect" for waste and it was slightly slightly bigger anywhere you have created more waste.
Sheet goods are best saved by reusing cuts and some builders are really good at that. Well, others are not. Fact is that everyone in this business pays and bills for square feet/meters no matter if the size fits some exact number of sheet material, or not.
