Yes, almost all US housing is timber frames (either 2x4 or 2x6 studs), but the exterior veneer depends greatly on where you live in the US. Where I live in Okl

Yes, almost all US housing is timber frames (either 2x4 or 2x6 studs), but the exterior veneer depends greatly on where you live in the US. Where I live in Oklahoma City, almost all of our houses are brick or stone on the outside. It's a veneer so it's not structural, but it provides a great thermal layer beyond just insulation between the timber studs. Brick is made locally in Oklahoma because the "red dirt" soil has a lot of clay in it, so bricks are actually the same price or cheaper than many siding products. Siding is really only widely used on second floors and "bonus rooms", etc. since brick is too heavy for the second floor and would require a lot more structural support. Most of the HOAs in newer neighborhoods around OKC will even require 70-80% brick or stone exteriors because it's lower maintenance and less likely to become an eyesore with fading/chipping paint, etc. So the requirements are pretty regional.