This is part two of my ‘How To Build A Small Cabin‘ series. If you haven’t read part one, you should go back and read How To Build A Small Cabin – The Planning Process.
The very first thing I did once I decided how big the cabin would be was to prepare the site. The site we chose was already relatively flat, and was pretty close to our trailer. This allows us to easily run power to the cabin and it gives the kids a better sense of security being closer to mom and dad!
When I laid the gravel pad on our new camp site area, I already knew where I was going to put the cabin so I left that area free from gravel. I used the tractor to do some final grading of the building site, and did some fine tuning with a shovel. I thought I was doing pretty good, but boy was I wrong…
I thought about a couple different foundation possibilities during the design phase. What I ended up deciding on is using precast concrete piers with 4×6 pressure treated timbers going between them. Unfortunately I didn’t take very many pictures of the early stages of the build, so I can’t really show you what I ended up with. Basically I used four of the piers, inset about 2′ from each corner so that it was well under the corner and the unsupported span of the timbers was relatively short.
Well, getting all four of these piers and the two timbers level and square was a huge pain in the ass. I spent about four hours on it getting it fine tuned. I’m glad I didn’t use three piers…I can’t imagine how hard it was to do. Eventually though I managed to get everything within about 1/4″ of level across the entire 12′ span. That’s pretty darn good. Might be a bit overkill, but I wanted the foundation in particular to be rock solid and level.
The Subfloor Frame
Designing the floor assembly was interesting. I was initially thinking that the foundation timbers would also act as part of the floor assembly, with floor joists hanging off of hangers. But since I wanted to bring the timbers in from the sides, I decided that I’d build a subfloor frame and simply set it on top of the timbers.
The subfloor frame was made with joists that were simply standard 2×6 dimensional lumber in 12′ lengths. I put them on 24″ centers and fastened a 2×6 across each end of the joists. This made a nice frame that was quite stable. I used metal 90 degree angle brackets to fasten each joist to the timber supports. Once this was done, the frame was rock solid.
Lesson Learned: Now I made a mistake in this step that I want to warn you against. To determine if everything was flush at the ends before putting on the boards on the end, I used one of the boards as a butt plate. Well, I should have measured instead, because the board I used was warped, and I ended up with a messed up frame that took a long time to fix, and it never got up to my level of perfection! In hindsight, I would have simply measured from the timbers to make sure everything was correct, and trusted my tape measure instead of the board.
The design of the floor looked like this:
Now after the floor frame was done, I was ready to put on the subfloor. Using my handy dandy reference manual I determined that my minimum thickness for the subfloor was 3/4″ plywood. My local builders supply store had delivered me some awesome tongue and groove 3/4″ plywood. Putting it on was pretty straight forward.
I picked one corner to start on and made sure that the plywood was even with the side of the frame, and fastened it down. My 12×12 floor used four full sheets and one half sheet of plywood. Compared to building the frame, the subfloor didn’t take that long to put together.
Lesson Learned: When I put the half sheet of plywood on, I wasn’t careful about the orientation of the plywood. What most people don’t know, and what I completely forgot about, was that plywood still has a grain. The orientation of the half sheet was such that the grain was with the joist run, instead of perpendicular to it. It bows now a bit when you walk on it. Ugh. At least it’s only on one corner, right?
Here’s a picture of what the floor looked like when it was almost done:
A Final Note … Short But Important!
By the way, if you decide you want to build one of these yourself, I HIGHLY RECOMMEND buying a book called The Graphic Guide To Frame Construction. Even though I’ve never built anything like this before, just using this book I was able to pick the right materials, decide on the right spans and distances between structural elements, and so on. Even if you don’t plan on building your own cabin, I think this book belongs on every preppers bookshelf.
In our next installment, we’ll talk about the walls!