Weekend #2 - we were able to finish our initial project. We installed all of the floor insulation, glued and screwed down the subfloor and cut the bottom plate to get ready for framing.
The insulation install went fairly smoothly, but it was a multi-step process and required a bit of math.
Step 1. We installed two 1" thick strips of foam insulation on the outside edges of the trailer. In this compartment the metal flashing on the bottom of the trailer is 6" deep.
Then we installed one layer of 1/2" thick insulation board over those strips of foam insulation on the edges of the trailer (for those keeping track, that is 2.5" of foam in the side compartments) and also in the center of the trailer where it was only 4" deep to the metal flashing on the bottom of the trailer.
Step 2. Then came time for the actual batts of insulation. Each batt is made for a 2x4 wall with studs 16" on center. We decided to go with Rockwool insulation, a mineral wool, for it's added R value and moisture and fire resistance. It cut like a loaf of bread and was easy manipulate into place. Just remember that unlike fiberglass, it does not have a vapor barrier attached. Side note: it is considered a greener alternative to fiberglass insulation.
Step 3. Next we had to coordinate putting the adhesive on and screwing down the subfloor piece by piece. As mentioned in our previous post, we only had 15 minutes to get the board screwed down from when we started putting down the adhesive. On the bigger boards we pushed right up to the 15 minute mark, but managed the challenge with two people. Pre-drilling all of the holes was critical to getting each board secured within the allotted time.
On Sunday we took it a little easy and did a little pre-work for our big framing weekend. We just cut the bottom plate and the headers over the wheel wells.
Next we frame up, so it will actually start looking like a house! And we are so lucky that a few experienced out-of-towners are coming to lend a hand.
I've been scouring the internet all day trying to find more people who used Rockwool in their subfloor as well, not just rigid foam! I'm doing my subfloor this week (hopefully..). I'm not sure if I have enough depth for rigid foam AND Rockwool, but I may check that out now. Did you do anything for a vapor barrier, since the Rockwool doesn't have one?
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DeleteWe went back and forth on doing a vapor barrier under the subfloor, but ultimately decided against it. I wish I could tell you it was because we did our research and give you references, but we couldn’t really find much information on it. Not for a lack of trying though as I’m sure you have found as well. Piecing together what we have been able to find though and from some knowledge gained while working in construction, it seems like vapor barriers in the southern US aren’t necessary, and could possibly even be harmful. Since that is where we are building and we will most likely stay in this region we decided against the vapor barrier.
A couple other reasons for going without a vapor barrier was because we will be putting in plumbing through the subfloor after it is down and it would be quite difficult to make a tight seal around the plumbing inside the trailer where the vapor barrier would be. Also we really wanted the subfloor adhesive to adhere directly to the trailer from the subfloor to limit bounce instead of with a vapor barrier in between them.
Good luck on your subfloor and with the rest of the build!
That's pretty much where I was at with my thinking as well - I want construction adhesive on the trailer directly to the plywood, and also doing plumbing through the subfloor after the fact. Good points. There's definitely a lack of information of the little minor details - everyone just talks about the big fun stuff! Thanks for your post and reply :) Good luck with the rest of your build too!
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