wall raising

Wall Raising

"Standing" in my door opening
I decided to use conventional wood stud construction to frame my house. It is what I am familiar with although I am interested in other methods like steel studs or SIPs (structural insulated panels). My build buddy, Lina, decided to design her house with SIPs and so I was able to learn more about them at her wall raising.
Raising the first wall!
I designed my house around dimensional lumber sizes so that I could reduce the amount of waste which has proved successful since it has been difficult to find scrap pieces of wood on site! Since my design is for a shed or skillion roof, one of my long walls is taller than the other. I used 2"x4"x8's for the short wall cut to stud length at 92 1/4" (some people use 92 5/8") so that the plywood sheathing would span from the bottom plate to the middle of the double top plate. Then I will rip another piece of plywood for the top once I have the rafters and blocking in place. I had originally designed this wall to be 9' from bottom of bottom plate to top of rafters so that I could use a single piece of 4'x9' plywood but then I learned that 9' sheets of plywood are actually not standard, need to be special ordered and cost twice as much as 8' sheets. I didn't want to lose a whole foot on that side so I compromised with the more conventional framing method. 
Raising the tall wall!
For the tall wall, I used 2"x4"x10's for the studs and had to trim off some of the ends since they were a little more than 10' long. I decided to go with an advanced framing method where I have the studs spaced at 24" on center vs. the 16" OC studs. This method minimizes the amount of lumber necessary and keeps the weight lower. Had I built this house on a fixed foundation, I would have used even less lumber due to wheel well considerations. I decided to put double studs on each side of the wheel wells to support the header hanger for the 2x6 spanning the 5' distance. Had the trailer been designed with 48" behind the wheel wells instead of 46", these extra pieces of lumber would have lined up with the layout. I also should have put full double studs in the corners for the tension ties since a single stud did not push the hanger in far enough to avoid drilling into the rear lights. (I originally wanted to have a 2 stud corner, one for the end of each adjacent wall to reduce thermal bridging.) I could probably have put the tension ties somewhere else with a double stud like at the wheel wells but I think code requires them within 1' of the corner. A friend suggested adding a 2x4 block to fur out the corner so that is what we decided to do. I am unsure of what this does structurally but I think that my sheathing will help.
Wheel header detail
Other considerations I had for my framing layout were the locations and sizes of my windows and door. I ordered two of my windows to be 48"x18" and three of them to be 24"x30" so that they would fall on my framing layout. However, I realized that I probably should have ordered them to be 22 1/2" and 46 1/2" wide as rough openings to account for the 1 1/2" total thickness of the studs on each side. But, since they are in bearing walls, I designed them to have insulated headers, trimmer studs and cripple studs under the sill edges in the center. As long as the framing layout landed on one of those members, I could not have really reduced the amount of lumber used. I learned from a structural engineer after framing that I could have used header hangers for the windows as well which makes sense. (He also said that the wheel well header hangers were overkill.) Had the windows had 22 1/2" and 46 1/2" wide rough openings, I could have used the studs as the vertical edges and a single flat 2x4 on top and bottom of the opening. This is very light framing and I worry that it would not be enough for a mobile structure to keep windows in place and from cracking. Since I put a lot of time, energy and money into my new windows, I did not want to test this method out. When I draw up new versions of my plans, I plan to try out both designs and see which one is more ideal.
Window framing
I still have not found a used door that I like and cannot justify spending over $500 for a new door so after I learned that standard entry doors are 32"x6'8", I made my RO 34" wide and 82 5/8" high until I find a door to fit.
Rafter framing
The rafters line up with the studs so I did not really need a double top plate but I decided it would be a good idea on my two long walls since they bear the roof load and because my house is mobile. Since I had designed the wall system the way I did, the angle of the roof pitch ended up being approximately 4:12. Since my roof only has one slope, the exact pitch was less of a concern. To make the rafters, we put a 2x4x8 on edge spanning the two long walls. With squares, we marked the end plumb cuts at the outside edge of the stud framing. (I did not design an overhang since I am wrapping the exterior with insulation to create a thermal break.) Again, since I had planned for minimal waste, they were just barely long enough. I cut the plumb lines and then marked the seat cuts for the birds mouths perpendicular to the plumb cut. Those were the only two cuts I needed to make for the short wall side but I had to make another plumb cut to line up with the inside of the tall wall. With this first piece as a template, I used it to measure and cut the remaining 9 rafters so that it could also be used as a backup piece if necessary (and it was). We installed them in place with Timber-Tite screws which was much faster than using the hurricane ties.
Timber-Tite screw
I framed the end walls in place with a single top plate since they are non load bearing and that is what I have seen in my research. I started by cutting the bottom plate to length and screwing it into the subfloor and floor box. Then I figured out the angle for the top plate and studs with scrap pieces. It ended up being 18 degrees. I measured and cut the top plate and two end studs. Then I installed these to create the outside frame. I needed three other studs per wall so I held them in place while I plumbed and marked the cut line. I learned that starting with the taller studs and working down to the smaller ones is beneficial if you accidentally cut one a little too short. Once these were all cut and installed, I added blocking at the 8' line so the top of the plywood sheathing would have something to tie into. It was a time intensive process but I was able to do it all by myself.
Framing in the rain
A note about fasteners. Screws take much longer to frame with than nails. Screws are usually used in mobile structures since they have more grip to stay in place over time. I used ones which required Phillips bits and would never do this again since they strip the screws easily and I have destroyed about 5 bits so far. Better screws to use are those with square or star drive heads. I would also like to more research into ring shank nails since I have used them for flooring and they are kind of like a nail/screw hybrid. I will likely be using them for my siding.

For more photos, check out my flickr!