I have a 2008 Jayco 28BHS that has formed a leak near the roof/side wall of the camper in the rear bunk bed area of the camper. So far, I can't find the leak, but I've gutted the whole area on the inside, so I know approximately where the water is coming in. I'm using fans and dehumidifier to dry it up. Anyhow, the water came down the inside of the walls and I've stripped everything down to the bare plywood floor. My question is what's under the floor? When I lay on the ground outside the camper and look at the underside, there's a black burlap type material that feels heavy in this area, but doesn't have this heavy feel on other parts of the underside of the camper. Is this wet material that I'm feeling? How do I access what's under the plywood floor? Do I do that from the underside and what all is under there? Also, I resealed everything that protrudes from the roof 5 months ago. The leak is not coming from any of those places. Any ideas where it could be coming from and what to do about moisture under the plywood floor? Thanks.

The best way to access the underside is to unfasten the Darco "cloth" or cut it. It can be repaired with gaffer's tape. If you have leaks and don't know the source, I'd suggest to do a pressurized leak test to the trailer. That will pinpoint any leak spots.

There's fiberglass insulation above the black fabric, or at least there should be.I found garbage (construction debris) in there too.There'll be bracing and other support members too.Cut it open and check it out, the fabric tapes back together nicely.

What is the black fabric under there? What's it called and where can I get more of it? Also, Westend mentioned gaffers tape to reseal it. I've never heard of gaffers tape. Is it known by other names and where do I get it? Will other types of tape work also? Thanks for the replies.

I had to replace a couple of pieces of the OSB subfloor. The only thing under the subfloor was some fiberglass insulation resting on the Darco fabric. The insulation was wet and ruined. I only needed a couple of small pieces, so I went to a construction site and the crew on site gave me enough.

plasticmaster wrote:What is the black fabric under there? What's it called and where can I get more of it? Also, Westend mentioned gaffers tape to reseal it. I've never heard of gaffers tape. Is it known by other names and where do I get it? Will other types of tape work also? Thanks for the replies.The stuff on mine looks like tyvek, and cuts like it - a bunch of plastic fibers woven in criss-crossing directions... just that it's black instead of white. I don't know where to get more, I imagine a rv parts store sells it in rolls. I considering using geo-textile (landscaping fabric) to repair my cuts if they could not be taped directly."Gaffers tape" is a catch-all label for a cloth tape with heavy adhesive, like duct tape is a catch-all for reinforced nylon/pvc tape with heavy adhesive. I used outdoor rated duct tape to repair the cuts I made in my underbelly.

What's in between the floor and underside of TT?

westend
Explorer
Nov 16, 2015
The best way to access the underside is to unfasten the Darco "cloth" or cut it. It can be repaired with gaffer's tape.

If you have leaks and don't know the source, I'd suggest to do a pressurized leak test to the trailer. That will pinpoint any leak spots.
GordonThree
Explorer
Nov 16, 2015
There's fiberglass insulation above the black fabric, or at least there should be.

I found garbage (construction debris) in there too.

There'll be bracing and other support members too.

Cut it open and check it out, the fabric tapes back together nicely.
plasticmaster
Explorer
Nov 16, 2015
What is the black fabric under there? What's it called and where can I get more of it? Also, Westend mentioned gaffers tape to reseal it. I've never heard of gaffers tape. Is it known by other names and where do I get it? Will other types of tape work also? Thanks for the replies.
Boband4
Explorer
Nov 16, 2015
I had to replace a couple of pieces of the OSB subfloor. The only thing under the subfloor was some fiberglass insulation resting on the Darco fabric. The insulation was wet and ruined. I only needed a couple of small pieces, so I went to a construction site and the crew on site gave me enough.
GordonThree
Explorer
Nov 16, 2015
plasticmaster wrote:
What is the black fabric under there? What's it called and where can I get more of it? Also, Westend mentioned gaffers tape to reseal it. I've never heard of gaffers tape. Is it known by other names and where do I get it? Will other types of tape work also? Thanks for the replies.

The stuff on mine looks like tyvek, and cuts like it - a bunch of plastic fibers woven in criss-crossing directions... just that it's black instead of white. I don't know where to get more, I imagine a rv parts store sells it in rolls. I considering using geo-textile (landscaping fabric) to repair my cuts if they could not be taped directly.

"Gaffers tape" is a catch-all label for a cloth tape with heavy adhesive, like duct tape is a catch-all for reinforced nylon/pvc tape with heavy adhesive. I used outdoor rated duct tape to repair the cuts I made in my underbelly.
RVcircus
Explorer II
Nov 16, 2015
The fabric material is Darco. A Google search will bring up suppliers.

We had the same issue with out TT. We had a roof leak and all of the water collected in the underbelly. There was a ton of water and wet fiberglass insulation in there. I would recommend cutting some slits to see if it drains. I removed all the Darco and insulation to let it dry and will be replacing it with foam board insulation covered with coroplast. Whatever you do, don't let the wet insulation sit in there.
GordonThree
Explorer
Nov 16, 2015
The stuff that came up when I googled Darco was fiberglass cloth for industrial welding applications, rated to 1000°F. Surely that's not the stuff being used on the bottoms of RVs? I guess if the glass fibers were thin enough they would cut with a steel knife, but it felt more like plastic as I cut it than glass... fireproof fiberglass cloth seems a bit high end for the rather cheap way they build RVs.

Darco cloth
CavemanCharlie
Explorer III
Nov 17, 2015
I don't know what the stuff is called but, I agree with cut a few small holes in it and see if any water comes out.

I've had to do that on my TT when a compartment door leaked. I drained all the water out and then cut the holes a little bit bigger so I could reach up in there and pull out the wet insulation.
hvac
Explorer
Nov 17, 2015
This is the one area that made me give up a beautiful and only 5 year old Airstream. Trapped moisture was making the plywood floor soft.

Nothing is perfect, but we are now 2 years into our 21 RBS Camplite and I think the solid aluminum floor is really showing its advantages. its simple but exposed on both sides and no surprises.
Gdetrailer
Explorer III
Nov 17, 2015
GordonThree wrote:
The stuff that came up when I googled Darco was fiberglass cloth for industrial welding applications, rated to 1000°F. Surely that's not the stuff being used on the bottoms of RVs? I guess if the glass fibers were thin enough they would cut with a steel knife, but it felt more like plastic as I cut it than glass... fireproof fiberglass cloth seems a bit high end for the rather cheap way they build RVs.

Darco cloth

Kind of doubt that..

Most likely is Tyvek.. Like the house wrap but only it is is dyed black..

TYVEK