Subfloor

[Brandon1078]

Can anyone tell me what to expect on the flooring of my 1998 Winnebago Adventurer 35? My floor has been spongy on an 18”x30” section in front of fridge. I’ve located and fixed the leak, so now I’m thinking about fixing the soft spot. I figure I’ll take circular saw and cut the bad section out. Will the floor have wooden frame? Aluminum? A couple layers? I can look under fridge and see there is plywood on top, since the linoleum doesn’t cover parts that aren’t seen under there. I’m just not sure if there will be more layers. I was hoping someone on here has done this job before. Thanks for any/all input.

[SLOweather]

Look around inside of cabinets (remove the bottom if necessary), up inside basement storage etc and somewhere you should find a floor penetration for plumbing or wiring that will help you see the floor construction.

[Brandon1078]

Thank you sir...it looks to have styrofoam directly under the plywood. I asked someone about that and they told me you can't tear this kind out...you have to build on top...why could I not cut out a 18"x30" section and replace the plywood and styrofoam? Isn't the styrofoam there to just cushion your steps...allow some "give"?

[SLOweather]

The RV floor, wall and roof construction is a plywood/foam sheet/plywood (or fiberglass for roofs and walls) sandwich construction. The "sandwich" is what gives it strength. The thin outer plywood sheets or skins are like membranes in tension and compression, given strength by the foam core. In building construction, they would be called SIP, structural insulated panels. Anything which majorly impacts the integrity of the skins affects the strength of the sandwich. The floor system is probably screwed to a metal frame.



It's rather like plywood in theory. The strength of the glued up plies is more than the strength of the individual plies added together.


As noted, the best way, IMO, to fix your floor is to overlay a patch of plywood that extends several inches past the bad section on all sides, gluing liberally with something like Gorilla Glue. Done carefully, and filled and sanded carefully, it shouldn't be too noticeable, depending on the thickness of the patch.



I suppose there are other ways to fix this. Others may weigh in.

[Brandon1078]

Thank you. I’ll wait and see if anyone has any other opinions before I tackle the job

[wmckinley]

x2 on SLOweather response. On a previous coach I had the same problem. My resolution was a little different. I laid down 3 layers of 6 oz fiberglass cloth extending 6 inches outside of the soft area. Using EPOXY resin ( can't use polyester resin as it will melt the Styrofoam) You laminate it just like building a part. Coat of resin, layer of cloth, roll it to get the bubbles out, rinse repeat, Do it all in one continuous operation. Floor ended up solid as a rock after cure.

If you can get to the other side of the floor, do the same process. Like SLOweather said, it is only structurally sound when sandwiched properly.

[SLOweather]

Thanks for the validation, wmckinley. I like your fiberglass solution.

[wmckinley]

Using the fiberglass ends up with a thinner patch. Bonus