Protecting subfloor from water damage

[unthinkablecreation]

Hi all,

So I've spent last month sealing the roof and windows of my GMC. The last couple of weeks have been rainy and a perfect time to test if my seals are
working. So far so good.

After driving around for a bit I noticed the subfloor around the wheel wells was soaking in water. Turns out the subfloor is completely exposed behind
the rear wheels.

Has anyone tries to seal this area from the elements?

--
Angel Rodriguez
San Jose, CA
1978 23' Birchhaven

 

[Jim Hupy]

Yes. Wheel splash from the inner fenders is the culprit. We have used
sealant tape that is made for roof seams on RVs. The stuff I used is $$$$$.
Like $10.00 a foot. It is available in various widths, and I used the stuff
that was about 6" wide to cover where the floor meets the inner fender. I
had the bogies out when i did this, so i could run a continuous patch along
the entire dual wheel well. I pressure washed the inner fender and bottom
of the coach floor under the coach. I then sprayed a similar product, made
by Rustoleum, to the stuff you see on TV that you can make a screen door
float with. It is product # 265494. LEAKSEAL flexible rubber coating. I
painted 2 or 3 coats, let it cure, applied the seam tape, and top coated
the tape and complete inner fender areas. Customer says no more leaks
there. His is a 73.
Jim Hupy

On Wed, May 29, 2019, 12:02 PM Angel Rodriguez via Gmclist <

> Hi all,
>
> So I've spent last month sealing the roof and windows of my GMC. The last
> couple of weeks have been rainy and a perfect time to test if my seals are
> working. So far so good.
>
> After driving around for a bit I noticed the subfloor around the wheel
> wells was soaking in water. Turns out the subfloor is completely exposed
> behind
> the rear wheels.
>
> Has anyone tries to seal this area from the elements?
>
>
> --
> Angel Rodriguez
> San Jose, CA
> 1978 23' Birchhaven
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>

 

[emerystora]

Yes, there is a crack along the floor at the bottom of the wheel liner. Use a polyurethane sealant that you can buy from Home Depot. It used to be PL but they were bought out by another company

It comes in different colors. I used the black.

Emery Stora
77 Kingsley
Frederick, CO

>
> Hi all,
>
> So I've spent last month sealing the roof and windows of my GMC. The last couple of weeks have been rainy and a perfect time to test if my seals are
> working. So far so good.
>
> After driving around for a bit I noticed the subfloor around the wheel wells was soaking in water. Turns out the subfloor is completely exposed behind
> the rear wheels.
>
> Has anyone tries to seal this area from the elements?
>
>
> --
> Angel Rodriguez
> San Jose, CA
> 1978 23' Birchhaven
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org

 

[unthinkablecreation]

thanks for the info!

Looks like I have some work to do
--
Angel Rodriguez
San Jose, CA
1978 23' Birchhaven

 

[Ken B]

That stupid leak drove me nuts for many years. Then I realized that it only leaks when you drive in the rain. I got the same Rustoleum product (same
as Flexshot) and sprayed all around that seam. It took slightly less than one can per wheel. I finished it with a roll of 6" wide aluminum at
Menards and glued a splash shield all the way around in front of that seam. I also used a few wood screws into the edge of the floor to make sure
that the shield would not go away some day.
--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana

 

[justin brady1]

When I redid mine I put several thick layers of deck sealing outdoor paint on the plywood around the wheel wells, and resealed the wells to the floor.
No leaks that I've noticed, but I do like the idea of putting a tape seal over the whole thing. I always thought that was a very poor design to have
end grain exposed in the wheel well like that! Would have been simple to put in an aluminum channel in the design phase to avoid exposed wood in such
a water soaked area.
Eternabond should do the trick I'd think
--
Justin Brady
http://www.thegmcrv.com/
1976 Palm Beach 455