Trillium 4500 rotten dub floor

[Patrick G.]

Did some searching but could find exactly what I was after.
There is a lot of rot under the fiberglass floor.. planning to cut out the fiberglass and replace the rotted plywood with new ply plywood. I was going to just glue down the new plywood and then seal the joint between the fiberglass and wood with fiberglass mat and epoxy. Then probably put a floor covering over the whole shebang.
Any input on a better or different way to do this?
Thanks!
Patrick

[David Tilston]

Patrick, That’s a big job. I have put a lot of thought in this subject. Your Trillium may also suffer from front curb side sag. The door is a rather large hole in the structure. The floor helps to hold up the section of the trailer forward of the door. To check this, stand on the tongue and look down the flat section of roof on the curb side. Does the front of the closet form a high point on the roof? Another test is to lay a 2x4 on its edge from the fridge door towards the trailer door. Is there a noticeable sag in the floor towards the trailer door? If so, before you fix the floor, you would want to jack up the front curb side for some time, till it no longer sags. Fibreglass is plastic. That is, it will deform when it is forced to. You would want the floor flat when you repair it.

The year of your Trillium would affect the procedure. 1979 and later Trilliums have what I call an "almost dinette" or an actual front dinette. The difference is moot for your purposes. If you have either, you just have more floor that needs to be fixed. The 1978 and earlier Trilliums have a front couch, (gaucho) with fibreglass floor to the rear and just plywood forward of it. I would still replace that plywood.

The fix that I would do is not for everyone. I want to eliminate all wood in the trailer, other than the cupboard doors. So, I would replace the plywood with pultruded fibreglass floor grating.
https://www.grainger.com/product/SAF...altItems_4AUA6
This stuff is 1” thick, not ¾” thick, so I will have to cut ¼” off the bottom of the gaucho, kitchen, closet, and the rise to the rear dinette. The door sill may need some work as well.
However, plywood would be much less expensive. The approach I would take is to grind the floor off, right down to the exterior shell, but not through it. This implies pulling the fridge, furnace and the cupboard doors. If you are using wood, instead of the pultruded grating, you would want to cut the front gaucho, (or dinette) and other fibreglass as close to the floor as possible. I would use a Dremel, with a cutoff wheel. Then feed the replacement plywood, cut to fit where it is going, (narrower between the wheel wells) into the hole that the fridge was in. I should go up to the door sill. Slide it both forward and rear. The last piece would span from below the fridge to the door. I would fasten all the furniture to the new plywood with pultruded angle, to keep it all straight. Then glass the top of the plywood to make the floor. I would also glass the top of the plywood in the front gaucho, which Trillium didn’t do. The front wall of the trailer, in the gaucho was commonalty balsa wood, encased in fibreglass. I have no advise for that section. My plan is to grind it off and glue the pultruded grating, (one I beam at a time around the curve where the floor meets the wall). I will go right up to the bottom of the gaucho bench. Then cover with FRP panel glued to the top of the I beams, bent around the curve. I also plan to put spray foam between the I beams, in the door and in the kitchen back splash.