Yesterday I ordered (and received) my floor box lumber, plywood, joist hangers, and nails. Today Dad and I suited up and got to work. So far--after about 3 1/2 hours of work--we've put together the outside rails and the main plywood-edge-supporting (A and B) joists.
Our strategies, results (good and bad), and lessons learned... after the jump!
Step 1:
First we prepped the trailer. It had some minor rusted bits from its stint sitting on our street (it now lives under cover at my grandparents' house), so we spray-painted over them with an anti-rust enamel in matching black.
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| Rust :-( |
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| Spraying over the rust |
Step 2:
I wanted a thermal break between all of the trailer metal and the floor box, so I put down a little cold-weather-compatible Liquid Nails (construction adhesive) and stuck Sill Seal (sill plate gasket) onto all of the trailer ribs. I could definitely feel the reduction in heat conduction with the Sill Seal versus without. That 1/4" layer of foam really makes a difference! And since it's designed for weight-bearing applications--for placing under the sill plate (AKA bottom plate/sole plate) upon which the rest of the wall is built--I hope it will hold up under the weight of the floor. Or maybe it will just crush and lose its insulating power... I'm not actually sure.
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| A bit of Liquid Nails... |
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| Trim Sill Seal to fit width of ribs. |
So: good idea? I hope so! Good idea to proceed immediately to the next steps without letting the adhesive cure? Uh... not really.
There was a lot of squelching and sliding of Sill Seal--and attempts to squelch and slide the Sill Seal back where it was supposed to go before the adhesive firmed up. Dumb.
Step 3:
We measured the lumber, remeasured the trailer, and cut pieces to make the side rails actually come in at 1" shorter than the inside of the trailer bed. We're aiming for 1/2" of wiggle room on all sides (not including the ~1/4" Sill Seal that will also go between the floor box and the trailer bed).
Lesson 1: My carefully calculated-on-paper measurements and figures were maybe a little bit of a waste of time--or, rather, they were just a guideline estimate, not gospel. Physically re-measuring the trailer and the lumber on-site was how we figured out how long we actually needed to cut the stuff to fit. For example, the trailer bed is really just shy of 19'2" long, and our 12' 2x6s were actually 12' 3/16" long; as a result, a piece of lumber that I had calculated should be 7'1" fit better when we cut it to 7' 1/2".
However! When putting in the first joists, it would not have been a good idea to physically measure how far apart the side rails were and cut the wood to fit, because our long side rails were slightly bowed. We needed to cut the joist to our calculated length and then bend the side rails in to meet it. Don't let curved lumber boss you around!
Step 4:
We glued and nailed the outside corners--the corners between the end and side rails (I'm sure there are technical terms for these pieces, but...). We did in two parts, since each side rail consists of two pieces of lumber. We used the trailer as a work surface and then slid the pieces in place to then attach them to each other with a plywood brace.
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| Predrilled holes 3/4 of the way from the end |
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| Three nails per corner--is this enough? |
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| Glue, too |
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| Plywood joining the side rail halves |
Step 5:
We shimmed the frame so it had the intended 1/2" of space on each end, then measured to find where to place the principal A and B joists. These are the joists that will support the ends of the subfloor plywood and need to fall 8' and 16' on center from the outside back edge of the trailer. Miraculously, our 3/8" plywood, stacked with a random piece of plywood we found lying around Grandpa's garage, added up to the 1/2" spacer we needed for this step.
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| Ta da! |
Step 6:
We cut joists A and B, attached joist hangers to them with the joist nails that the local building supply company selected for us, then attached the joist (by its hanger) to the side rails at the spots we measured. We successfully remembered to attach the joists upside down, since this whole assemblage will get flipped over once we attach and paint the plywood undercarriage! (We are dreading that step--it's going to be heavy.)
Lesson 2: Joist hangers are one thing where nails are really better than screws. I was a little leery of using nails anywhere in my tiny house because I had the idea that screws would hold up to vibration better; however, I've learned that in some applications, nails are better because they have more shear strength. That means that when force is applied perpendicular to the nail, it won't break as easily as a screw would. So, for weight-bearing applications like joists and joist hangers, use nails.
I'm still a little unsure of whether nails were the right choice for the outside corners. Is there some kind of metal tie, like a joist hanger but for these outside corners? I think I would feel better if they had some extra support. Maybe I'm worrying too much.
But at the end of the day, my feeling was totally on the I can do this! end of the emotional spectrum. Tomorrow will be a new year (hello 2015!) and hopefully a few more joists will find their way into the Going Home.
Happy New Year's Eve!
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