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Ask Dave: The wood in my RV’s roof is separating. What can I do?

Dave Solberg is a leading expert in the RV industry and author of the “RV Handbook” as well as the Managing Editor of the RV Repair Club. Today he discusses RV roof repairs.

Dear Dave,
I have a 2009 Mobile Suites 5th wheel. There are two areas on the roof where the wood under the rubber roof are separating from the cross studs. They have not pierced the rubber but they move up and down when walked on. I previously repaired a cut in the rubber from a tree branch with Eternabond applied over the existing damaged rubber and it worked incredibly well. My question is this: Is it advisable to cut away some of the rubber roof above the loosened wood, refasten the wood to the studs, then repair the area with Eternabond or some equivalent? Or, do you have a better suggestion short of replacing the entire roof?  —Ron

Dear Ron,
I am not familiar with the exact construction of your 2009 Mobile Suites roof. However, I would assume it’s the typical vacuformed sandwich design most use. During construction they lay out sheets of thin luaun, typically 1/8″ – 1/4”, and then apply adhesive, add the wood framework, and insert either block foam insulation or loose fill into the cavities. Then they add more adhesive, a layer of 1/8” luaun sheeting and the interior ceiling material. This all goes into a vacuum machine to compress and allow the adhesive to cure and sandwich everything together. Then they apply the rubber membrane while the unit rolls down the line, again with adhesive and wrapped around the sides.

According to the DRV website, they use aluminum roof rafters 16” on center. However, it does not say what size. These, of course, are the 2022 models, so yours might be different.

Start by contacting DRV

I would suggest contacting their customer service department at 260-562-1075, to find out what exactly you are trying to attach to. Some manufacturers use a thin metal “ribbon” type of rafter that is 2” tall but only about 1/8” or less in thickness. Their theory is the ribbon placed vertically and sandwiched with block foam insulation provides enough structural integrity. However, it won’t provide much for you to reattach the wood. Check out the diagram of their construction here.

If you have wood panels that are loose, my guess is there is delamination from either a moisture leak or twisting. In either case, it needs to be addressed as the loose panels will eventually rub through the rubber membrane and could get worse.

Also ask DRV if the cross members are wood or aluminum, and if they have a diagram showing location. I doubt they do. However, if they are 16” on center, then you should be able to find the cross members by locating ones by the roof AC unit and measuring. I have also been able to find them using a stud finder.

Locate cross members, then cut the rubber membrane

Once you locate the cross members, cut the rubber membrane directly in the center starting with a 2′-3’ cut to start and see if you can peel it back. I doubt you will see anything other than a wood panel with glue, but it would be important to know if it is at a seam. If the cross members are wood, you will be able to reattach the roof wood to the cross members with flat head screws. If not, it will be more challenging as you cannot get adhesive underneath the wood to the insulation and whatever cross members. In that case, you might need to add metal strips inside and out and fasten them.

We used to do this with sagging roofs by taking a 1” steel beam with a 2” curve or bend and install it inside the rig using a basement jack to lift the roof. Then put a flat steel strip on the roof and run self-tapping screws down into the 1” inside beam every 12”. You could do the same but not need the thicker inside as it probably will not need to support the roof. This will allow you to sandwich and secure the entire roof construction.

Something to consider is what you want to use to fasten the outer and inner brace. If you use screws, one piece will need to be thick enough for the screw to penetrate and grip without protruding out. You can use flat steel if you have access to a fairly large pop rivet and gun.

The ceiling might be slightly messed up during RV roof repairs

This means you will need to slightly mess up the ceiling material inside your rig, as well. However, this can be covered with a decorative wood piece or molding that matches the ceiling material covering. Your rig probably has several seams already present, since most don’t use a full sheet of fabric front to back anymore to reduce cost and reduce sagging.

As for the RV roof repair, I would fold back the rubber membrane, use Eternabond, and cover it with Dicor self-leveling roof sealant, the type that comes in a gallon can and rolls on.

Let us know what you find and how it comes out. I’d love to post a follow-up. If you can take photos of your RV roof repair job, we could even use it for our new video segment.

Read more from Dave here

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Eric
7 days ago

I will tackle most RV repairs myself. This one sounds like opening a serious can of worms.
I wouldn’t consider it unless the rig could be parked under cover for as long as it might take to sort it all out.
I wonder if, instead of tearing into the entire section of “wood”, a layer of 1/4″ plywood could be bent over and fastened over the damaged area, then of course covered with a new layer of membrane?
It would be a much lower risk approach, if it turns out to be feasible.

Jesse Crouse
11 days ago

You might think about finding someone with RV roof experience as this sounds like a somewhat complex and only a one shot repair.

Tommy Molnar
11 days ago
Reply to  Jesse Crouse

My thoughts exactly, Jesse. No way would I want to take this on.

Clayobx
11 days ago
Reply to  Tommy Molnar

Indeed,..a job for a very good tech. Pricy for sure but you have a nice 5er.