At this point we have the roof sheathed, hurricane straps installed, and four of our windows framed. Progress seems to be slowing a bit in the warmer months. The weather in the shop at 14′ is completely different than being outside. Could be the AC from the office pumping hot air into the shop floor or the metal roof but, wow!
It’s really coming together! This weekend we finished the walls and started sheathing. There’s a completely different vibe standing on the trailer now. Once enclosed, you can really start to visualize the space.
The green stuff you see is a special product called “Zip System.” Rather than simply using standard OSB or plywood, this stuff has a waterproof coating on one side. Each of the seams will be covered by rubber. This creates an air and water barrier around the whole structure. It costs a bit more but it appears to be well worth it.
One of Fred’s friends, Dan Korb, pointed out the fasteners we were using to anchor the foundation to the trailer. Initially, we were using 5/8″ zinc-plated bolts with jam nuts. However, after finding a vendor who could supply them in a decent time frame, they were all replaced with their Grade 8 equivalents and a gob of red thread-locker.
This increased each bolt from a load strength of 33,000 pounds to 120,000 pounds. The tensile strength of each one increased from 60,000 pounds to 150,000 pounds. So, yeah, we’re set.
Headers were fun (not). The headers above the doors were more “normal” than the sides, since the lumber can be cut and tossed around by one person. However, the sides were… wow. All headers were built by fusing a 1/2″ sheet of ply between two “two bys”… either 2×4, 2×6, or 2×12.
Not sure, but I think this is weekend #2 of framing the walls. We were able to get up the majority of the left side as well as install the headers for the two entrances. The rear entrance is much taller than the front since the floor will be raised almost 15″ in the rear half.
Next up are the mid-sections. See those wide boards on the floor? Those are to span the wheel wells and are incredibly awkward (a 1/2″ thick piece of ply glued between two 2×12’s)!
Framing started today with 115 kiln-dried Douglas Fir 2x4x12’s. Bought almost every decent board they had.
The first section of the right all (the front) was torture. Also got to play with a shiny new Dewalt framing nailer. Love that thing!
Bolted down the sole plates today. This foundation isn’t going anywhere… ever. Every 16″ is a 5/8″ x 7″ zinc-plated hex bolt. These bolts run through the sill plate, through the subfloor, the foundation, and through the 4″ angle iron lip on either side of the trailer.
When it comes time to build the walls, each sill plate will be unbolted and become part of the wall. Each 9’6″ stud will land in between the bolts. And, finally, the walls will be lifted up 28.25″ onto the subfloor and bolted back into position one last time.
Two 2x12x12 headers prepped and curing for the weekend.
Foundation is done!
First, we skinned the top of the trailer (belly of the foundation) with 20″ strips of aluminum flashing using construction adhesive. By overlapping each strip by 2″ we created an “escape route” for any water that may find its way into the house but yet sealed it enough so varmints won’t be able to get in. Also, the overlapping pattern is set to allow air to flow over the skin when the house is being towed.
The foundation structure is made of kiln-dried 2×4″ Doug Fir prime dimensional lumber. Not much to say about it other than, it’s the good stuff.
We chose to go with battens of formaldehyde free / vapor retardant Owens Corning fiberglass insulation. The combination of this with the air gap created by the raised floor should be more than sufficient.
Finally, we chose T&G Dryply Plywood for the subfloor. It has a water-repellant coating on the top. It’s not as heavy as ground contact (GC) ply, but it should add a slight bit of protection should any moisture find its way from a spilled glass of something down the road.
The trailer is ready for the foundation!
We added over 40 gussets along the sides of the trailer. They are probably overkill, but I’d like to be a bit anal with this build. Once they were ready, we drilled a series of 3/4″ holes down each side to anchor the foundation to the trailer.
Small side note: this part sucked! By hole #2 I was ready to go buy a plasma cutter and melt the holes! I realize you’re supposed to go “low and slow” while drilling metal, however such is not possible with a hand-held drill. Sure, you can take your time with the drilling, however, conventional drill bit sets have such a huge jump in sizes after 1/4″. While I did end up switching to a step bit, it still took forever. In the end, I decided to burn through five or six step bits to get through the holes as quickly as possible. It worked, but I was sick from the fumes for a good two days.