Soft spot on the roof needs to be fixed need advice

I have made similar repairs and will suggest you roll the rubber carefully back away from the damaged area and then clean and cover the rubber before removing any of the damaged wood. If not, the saw dust from the wood work will stick to the adhesive still on the rubber and cause you quadruple the work.

I tried the PL adhesive on the first RV I worked on for re-attaching the plywood to the roof and walls and the fiberglass to the wood. It didn't cure quick.(after 3 days it was still not cured). I assume it is an air cured adhesive. Started over and experimented with different adhesives.

Moisture Cured Polyurethane worked best for me,(Gorilla glue). It expands and fills the cracks and crevices. You'll have to weight or clamp the wood in place to keep the adhesive from expanding and moving it.

If your damaged area is still wet it will take a bit to dry. I have had to lift the rubber and fiberglass away from the insulation for about a week before every thing seemed to be very dry.

The rubber is attached with either contact cement(older method)or a water based acrylic adhesive. For contact cement, you roll it on both surfaces a few feet at a time and let it dry before rolling the rubber out. The acrylic is rolled on to the wood and then the rubber rolled out on the roof while it is still wet.

Beaded Polystyrene does hold water, so make sure it is dry before closing the roof up. If you aren't sure, the expanded sheet insulation the home stores sell is a good replacement and isn't too expensive.

Good luck with the project.

Your welcome to PM me if you need more opinion.

Even if it's vacuum bonded which I doubt, the plywood should be cut back as far as necessary, remove and replace the styrofoam, and screw the new plywood to the aluminum rafters
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Styrofoam does absorb water - and takes forever to dry, especially in enclosed space. Ask any boater. The "skin" repels water but when it's broken, water easily comes between the grains.

Dr Quick wrote:
I have replace the entire roof on one trailer, roof material and deck. On another trailer I had to repair a front corner that had leaked. I pealed the roofing material back just like you mentioned. Both trailers were wood joist with bat insulation.
If I can be of some help send me a PM.

PS. my wife is from London, Canada

We are in Waterloo which is about an hour east of London. Thanks for the PM offer. Will contact you if I run into a problem.

Thanks,
Rob

Thanks everyone for the great responses. From what rjxj says it sounds like my assumption of pretty straight forward is about right.

B.O. I sure hope you are correct and it is not vacuum bonded. It that's the case then the inside bit of water damage should be easier to fix too but another time for that. Looks like I have a project to do in the next number of weeks. Will wait for a nice dry weekend to do this.

Tyler0215 wrote:
You will have to replace the styrofoam also. it will never dry out. You don't want to cover anything up that is wet or you will get mold and mildew.

Styrofoam is plastic and doesn't absorb water. I wouldn't worry about replacing it. Roof sections are not generally made with a vacuum bonding process. They are assembled with the foam insulation friction fitted and the roof decking screwed in place.


B.O.

I have replace the entire roof on one trailer, roof material and deck. On another trailer I had to repair a front corner that had leaked. I pealed the roofing material back just like you mentioned. Both trailers were wood joist with bat insulation.
If I can be of some help send me a PM.

PS. my wife is from London, Canada

My son has a 2008 Rockwood that leaked because of a small gouge under the edge of the ac unit that couldn't be seen. He had a quote of over $5,000 to repair any bad wood and new tpo. They also quoted for just removing the front trim and doing an open heart surgery cut back to the ac unit, patch in a piece of wood and glue it and seal it back up $3,200. Without a lengthy explanation of all the stuff he had going on at the time he decided to fix it himself. He figured he could cobble it just as well as they could and did it for $200.

We ended up cutting out less than a sheet of plywood. I dont recall a big problem with the plywood sticking to the foam board. We glued and clamped wood scraps to bridge the joints and let them dry. We then glued everything well and set the patch in and weighted it down.

The ugly part was pulling the tpo back as the felt was stuck real well. We used a razor knife close to the wood in some areas to get it to separate. The only problem we had was with the Dicor glue. The felt that was now on both surfaces didn't adhere well. In the end there were some loose areas so we stapled it down and dicor everything. Half A-- but what are you going to do? He's still using it 2 years later with no problems. He isn't real enthused with Rockwood because the floor had soft spots too.

If I did something like that again I would call Dicor and see if contact cement could be used. I cant see why it wouldn't work with a felt back tpo. Many will tell you that contact cement will damage epdm but it wont. I called Dicor and asked about their glue and why contact cement cant be used. She said the only reason they recommend that type of adhesive is because contact cement is a one shot deal and people would mess it up.

I put an epdm roof on a little homemade TT with a plywood roof. I prepped it well and applied contact cement in sections about 2 feet log. It came out smooth as a baby butt with not one spot or loose area.

The other thing we were able to do is reinforce the cavities around the ac opening. We glued wood blocks in the cavities because the ac gasket compression was collapsing the inner and outer roof panels. Pretty poor construction.

CaLBaR wrote:
...
4. I believe that the TPO is felt backed so I would need to let this dry out but then just glue it back down. I imagine I could get the glue from the local RV shop?

TPO no felt backing IMO

Check out short video. https://www.youtube.com/watch?v=KL5qJw397Rc

Also around 2010-2014 some rv OEM's put on what is called "Alpha" Which is junk IMO.

You could also be in for a real surprise once you pull back roof. But water damage usually looks worse than it really is.

You will have to replace the styrofoam also. it will never dry out. You don't want to cover anything up that is wet or you will get mold and mildew.