As with the floor, we decided to frame the walls with 2x6s for added rigidity and space for insulation. The 24-inch spacing allows less thermal bridging (conduction through the studs) than 16-inch spacing as is necessary with traditional 2×4 framing. The increased spacing also reduces the weight difference that might otherwise pose a problem for those building on a trailer.
Framing is actually simpler than I expected. I decided early on that screwing the studs together would be necessitated by the torsion stresses the house would face in highway travel. We plan on being more sedentary than most tiny-housers, but we’re building with other future owners of the home in mind.
Before we began designing our framing diagrams we purchased all of our windows. Most of the windows came from the Habitat for Humanity’s ReStore. They have some great building materials far cheaper than even Craigslist usually offers. Our design is intended to utilize passive solar for chilly high elevation winters with our south-facing wall containing 4 windows (approximately 30% glass by surface area). The sliding glass door that we purchased, as well as one of our larger windows were both already jambed and we were able to simply use those dimensions for framing design. For the remaining 6 windows we added 1 inch on all sides to a lot for framing in our designs.
The walls came together more quickly than I had anticipated. Using a cheap (I believe it cost me $100-$120) battery-powered saw and drill set, the walls were up in a week. I was continually waiting on my batteries to charge and I would strongly recommend a traditional corded circular saw or miter saw for this part of the project. I ended up buying one after framing and utilized it for sheathing.
Our roof framing is quite simple and consists merely of 2x4s placed across the 8’ wall span at 24’’ OC. Upon sheathing the roof, this is more than enough capacity for me to wall on without any noticeable “give”. The roof overhangs the wall framing by 3’’ on both sides and 1’ at each end providing rain protection at the entry way and over our utility space.