15/32 BC plywood, Refectix, and cork here I go…any last minute concerns?

[simple sanctuary]

Dear forum folks, I can't begin to estimate how many hours I've spent thinking and researching my subfloor repair plan. My friend is coming over to help me tomorrow so if you have any big concerns about my current plan of action (below), please speak up now!

I'm replacing the 4x8 section that had rotted out in the back under the twin beds. What I pulled out is 15/32 and so I'm planning to replace with the same depth and use a sheet of BC plywood (which has exterior glue but not as off gassing as marine grade--I'll be living in the trailer full-time by July and want to decrease the chemicals I'm ingesting as I sleep and live in this small space).

I've read to seal the edge of the plywood all the way around the perimeter plus a few inches on top and bottom to give it extra leak repelling abilities (I did just spend 5 days, yes you read that correctly, 5 days caulking the exterior so fingers crossed that will keep me dry for awhile).

Is this precautionary sealing of the plywood edge only if I'm using regular underlayment? Or also advisable for any plywood including BC grade with exterior glue?

I've also read various products being used to seal the edge of the plywood. Since I'd like less chemicals/off gassing, would a water based primer work sufficiently?

Then there's the insulation. What I'm planning right now is to staple the Reflectix foil covered bubble wrap to the underside of the plywood before I lay it down on the chassis. I thought I'd poke a few small weep holes in the bubble wrap in case of a future leak and not wanting to hold the water up under the plywood. What do you think? (I don't have the belly pan off so screwing foam board to the bottom of the plywood in between the chassis wouldn't be a possibility and I don't want fiberglass to end up laying wet and nasty in the belly pan like the stuff I pulled out).

As for flooring, I think I might go with floating cork I can snap in place and just pray that I don't have any undetected leaks along the perimeter of the wall (or anywhere). There's a local green hardware store that has a white colored cork (with little grey flecks) on sale and I think that would help lighten the space up while adding a little R value too. Not planning to put any underlayment under the cork so the plywood and everything can breath.

So there you have it…advice, thumbs up, and clarifying questions most welcome!

Huge gratitude as always!
~Kim

[aquinob]

Kim

What year is this trailer? I'm sorta surprised that they used 1/2" ply for a subfloor, mine (a '73) used 3/4" and I would think that would be the minimum I would want to keep flex and sag to a minimum. Sealing up the edges with epoxy or a good paint or sealer will help keep the edges from absorbing water. There are plenty of 40 year old trailers that have most of the original plywood floors intact without any sealing coating on them, though they do rot in from the edge or any penetrations. I suppose a water base would be OK, but I would go with an oil base. I don't think you will have any problems with out gassing.

I really don't see how much good the reflectix is going to do on the bottom of the trailer. Its designed to reflect radiant energy and there is very little of that coming up from the ground. I can see it if you had pulled off the inner skin and wanted to replace the old pink glass, but underneath I would use some sort of foam or urethane board that would give you some level of R value. I used the pink XPS type board that has a value of R4 for 3/4" doubled up to R8. Also, the reflectix needs a dead air space between it and the outer surface of the area you want to insulate in order to have an R value greater than 1.1 If you are stapling it directly to the underside of the subfloor, then your R value is only R1. About Reflective Technology | Performance Information

Caulking is a necessary evil, and I can sympathize with how many days it takes to do it right. I still have a window to do on mine and for a neat job it can take a couple of hours to scrape it, and put some tape down so you get a nice clean edge when you are done.

[68 TWind]

Bob is correct in that a lot of old trailers have intact floors but many have rot. I felt that anything I could do to help create an extra barrier on the edge of my sub floor would pay dividends sometime down the road (maybe not me but for some future owner). I used 2 light coats of West System epoxy on the edges (a 6 inch band top and bottom) of the all the plywood when I rebuilt the rear bath area in my 68. After a couple of years I noticed a small area where water was getting in around the bumper trunk but upon close inspection the wood was fine. I think epoxy creates the best barrier against water along the edge that you get. I can't comment on off gasing from epoxy resins from a technical point of view but I can tell you that after it was dry for a couple days I could detect no smell of any kind. Treating the edges is kind of like a fire extinquisher, you hope you never need it but are sure glad to have it if you do.

[simple sanctuary]

Thanks Bob, Bruce & Rachel.

Yep, I was surprised to find the 1/2" subfloor. Mine is a 1981 Excella. Since most of the floor (except for the 4x8 sheet in the back and a small soft spot up front I need to patch) is still holding up strong, I thought I'd go with what was there instead of needing to sand etc to get the pieces flush.

I hear you Bob about the Reflectix not doing much for insulation the way/place I'm installing it (with no dead air space other than the bubbles themselves). With the belly pan on, I can't figure out a way to install foam board without just laying it on top of the belly pan--that would be too much dead space but at least it wouldn't soak up water like the fiberglass.

I'll go back over to Lowe's Hardware tomorrow morning (I'm there like every day to see if they have an epoxy with lower VOCs.

~Kim

[simple sanctuary]

Bob, how did you attach the foam board to your subfloor--belly pan off I assume? Thanks!

[aquinob]

Originally Posted by simple sanctuary

Bob, how did you attach the foam board to your subfloor--belly pan off I assume? Thanks!

Yes, belly pan was off. I needed to do the maintenance on the frame along with a good visual inspection. I doubled up the board to 1.5 inches and used some 2" deck screws with fender washers to hold it up. On mine I did the rear half last year and the front half this year. You can see the details in my blog <points down>