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Stick-built houses in New Zealand (maybe Australia too?) don't use exterior sheathing. They rely on more horizontal cross members between studs and the interior

Stick-built houses in New Zealand (maybe Australia too?) don't use exterior sheathing. They rely on more horizontal cross members between studs and the interior drywall for shear strength. The drywall is specially rated for shear strength applications, and there needs to be screws every 5cm at the corners.

zdragnar 4y ago
Interesting- is it for climate reasons? Curiously, both the international building code and ANSI require nails be used for wooden structural panels, because nails have better shear resistance than screws, which are typically designed with withdrawing resistance in mind. Obviously, nails don't exactly work very well with normal drywall, though I'm not familiar with structural drywall either so I'm going to assume that's why you need so many screws... one snaps and it becomes a cascading force multiplication on the remaining screws.
- frosted-flakes 4y ago
  I'm not sure exactly why because I'm not from there, I've just seen the practice in a bunch of YouTube videos. I think historically houses there have always been very built very lightweight without exterior sheathing, and maybe it's just inertia that resists the increased cost that exterior sheathing would bring. They also build with 2x4 exterior stud walls and nearly all homes are single-storey slab-on-grade structures, whereas most of North America has moved to 2x6 exterior walls as standard (partly because it allows for more insulation) and multi-storey houses are common. I don't know what to think about it, to be honest. Here in Canada I've started to see a lot of houses built with fibreboard sheathing with an integrated 1/2" or 3/4" outer foam insulation layer. The stuff is very flimsy and turns into oatmeal when it gets wet, but apparently it's sufficient. Builders use it because it's cheap and increases insulation and decreases thermal bridging, but I think I would prefer regular OSB sheathing with building paper, or Zip sheathing with taped seams if I could get it (I've never seen it used here before).

zdragnar 4y ago

Interesting- is it for climate reasons? Curiously, both the international building code and ANSI require nails be used for wooden structural panels, because nails have better shear resistance than screws, which are typically designed with withdrawing resistance in mind. Obviously, nails don't exactly work very well with normal drywall, though I'm not familiar with structural drywall either so I'm going to assume that's why you need so many screws... one snaps and it becomes a cascading force multiplication on the remaining screws.

frosted-flakes 4y ago
I'm not sure exactly why because I'm not from there, I've just seen the practice in a bunch of YouTube videos. I think historically houses there have always been very built very lightweight without exterior sheathing, and maybe it's just inertia that resists the increased cost that exterior sheathing would bring. They also build with 2x4 exterior stud walls and nearly all homes are single-storey slab-on-grade structures, whereas most of North America has moved to 2x6 exterior walls as standard (partly because it allows for more insulation) and multi-storey houses are common. I don't know what to think about it, to be honest. Here in Canada I've started to see a lot of houses built with fibreboard sheathing with an integrated 1/2" or 3/4" outer foam insulation layer. The stuff is very flimsy and turns into oatmeal when it gets wet, but apparently it's sufficient. Builders use it because it's cheap and increases insulation and decreases thermal bridging, but I think I would prefer regular OSB sheathing with building paper, or Zip sheathing with taped seams if I could get it (I've never seen it used here before).