Second Floor Framing
The second floor had to be built up to make room for the plumbing, electrical, and heating runs.
The first step was leveling off the log joists. To do that, we ran string lines over the tops of the joists to see how much they varied. Then with a hammer, we turned the screws on the floor jacks supporting the second floor to adjust the height. We periodically checked the level as the logs settled and adjusted the jacks as needed.
Tongue and Groove Subfloor
We used incense cedar tongue-and-groove boards for the subfloor of the second floor. These are the same as we used for the ceiling. And we put them face down since they'll be visible from the first floor.
We nailed them in perpendicular to the joists and cut them so the joints landed on the logs. We weren't concerned about the nail heads showing since this was going to be covered up by more framing and a finished floor.
The ends of the boards slid into the grooves cut in the logs during construction. This saved us the work of scribing the end of each board to match the log.
Running Pipes and Ducts Through Floor
Our contractors ran their ducts, wires and pipes across the subfloor for the upstairs bathroom and bedrooms.
Then we laid 2x4 "sleepers" around them to build up the finished floor. We set these on builders felt to limit the creaking between the 2x4's and the subfloor.
The sleepers function like floor joists. They gave us a nailing surface for the plywood subfloor that went down next. We secured them 16 inches on-center except where the ducts forced us to offset them. We also ran them along the logs at the perimeter of the floor so we'd have support for the outside edges of the subfloor.
To make a tight seal between the plywood and the sleepers we put a bead of construction adhesive along the top of each 2x4.
Framing Bedroom Walls
On the upstairs we needed walls to separate the three bedrooms and the hallway. We notched the logs wherever a stud wall ran into them, like we did on the first floor.
We raised the first section of the wall directly under the purlin. This was an 11-foot space so we started off with an 8-foot wall section and secured that.
Then we made the top section of the wall. We cut the cripple studs for this section a couple of inches short of what we needed to reach the purlin. This gave us enough room to allow for a slip joint. Then we attached that section to the purlin, and used lag bolts to hold both sections in line.
When we paneled these walls, we nailed a trim board to the top section that covers the gap and slides down over the bottom wall as the logs settle.