What Would Cause A Bulge On The Side Wall Of Our RV?

by Leroy Leonhardt

We purchased a 1998 brave winnebego.We noticed a bulge in the left side.I don't see any sign of a leak inside the motorhome.

ANSWER Hi Leroy, unfortunately it sounds like the side wall of your RV is delaminating. In the majority of cases delamination occurs when moisture gets into the wall and compromises the adhesive holding the RV laminated walls together. The fiberglass layer starts to separate from the rest of the layers of the wall.

This delamination will only get worse until the source of the moisture is discovered and repaired. Even though you may not see signs of leakage, the moisture is getting in-between the wall layers from somewhere.

Since you do not say exactly where on the RV the delamination is occurring, I will give you some suggestions on what to look for based on the location of the delamination.

If you notice the delamination is in close proximity to a window on the RV. Then in all likelihood that window has to be removed and resealed. The removal and resealing of an RV window is not as complicated as it sounds.

If the delamination is showing close to the roof of the RV then the roof needs to be inspected for any leaks that would allow water to get between the layers of the wall.

If delamination is occurring below the interior floor line of the RV, you need to start checking for any water pipes running under the cabinets etc.

Leaks can also occur in areas located near any RV Accessory that is screwed into or mounted on the exterior RV walls. Examples would be Mirrors, Ladders, awnings, electrical sockets, lights, any exterior mounting brackets, etc. If this is the case, the RV accessory needs to be removed and reinstalled using new gaskets and insuring that all screws and fasteners are put back into place using the proper sealant on the threads, etc.

If you still cannot find the leak using the procedures above, there is one more possible cause you can look for. In some very rare cases, excessive heat has caused the walls of certain RVs to delaminate. If you find that the delamination is in close proximity to a heat source such as a heater or water heater exhaust duct, etc. this might be the source of your problem. The heat can affect the adhesive.

In some even rarer instances dark colored decals on RVs that are exposed to desert like temperatures for a great length of time have caused some delamination to the walls under the decals.

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Until the cause of the problem is found delamination will continue. If the delamination continues it can affect the structural integrity of the RV. So this is something that must be addressed immediately.

Delaminated RV walls can be repaired. That is the good news, the bad news is that it is not a do-it-yourself job and it can, depending on the severity of the delamination, be a very expensive repair. If you want to get it repaired, you should contact one of your local RV dealers and ask if they can recommend a company to do the repair. Most normal body shops cannot do these repairs. A quality RV body shop can do the repairs and will do the best they can at matching the gel coat color etc.

I am very sorry that this is happening to you. You do not say whether you bought this RV from a private seller or an RV dealer, either way when it comes to buying a used RV, they are usually sold AS-IS. That is why I recommend that anyone buying a used RV should perform a Used RV Inspection.

I hope that you are able to get this problem resolved quickly, so you can get out there and start your RVing adventures.

Do you have any suggestions or comments on this topic? You can add them to this page by clicking on the "Click Here To Post Comments" link located near the bottom of this page.

Happy RVing

RVing Al

Comments for What Would Cause A Bulge On The Side Wall Of Our RV?

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by: Anonymous

Sometimes it's not the craftsmanship, sometimes it's the leveler!!! I have a friend(famous quotes) who didn't level his/her camper & when that person turned on the AC the water from the AC unit ran into the walls of thier camper causing the walls to bubble!!! Sorry to bust any "BUBBLES" on thoughts of legal actions but all warranties start with this statement "when properly used"(something like that), in their defence when they Baugh their camper from Camping World and they went thru their walk thru it was more like a run thru!!! I know this because I was there as a witness to this fact!!! The new owner kept saying this is my first camper!!!, wI'll this be ok???, these manuals don't look right, etc, etc!!!
Moral of the story make them take the time to pull out the crayons & paper!!!

Pointy bumps on interior wall
by: Skylar

We have a 2016 heartland cyclone 4200 we resently noticed that the wall directly to the right when walking in has these bumps that are very pointy almost as if needles are poking in. Anyone else have these problems? I have pics that can help. Can someone help me out?

3014 Cougat 5th Wheel
by: Sandy

At the end of 2013 we purchased from Camping World a new 2014 Cougar 5th Wheel It's always maintained as it should be. We've noticed on the left upper outside it looks like a stud is pushing out and now bulging. Any suggestions???

How to determine where a leak is.
by: Tami

Have a 2005 Holiday Rambler Savory 5th wheel. It has a big picture window in the back. The problem is the corners on each side of the window leaks, but not all the time. We have sealed and resealed that window and still has the same problem. Also sealed the corners outside of the camper. Does anyone know what we need to do.

Delamination Issues
by: MsPat

The passenger wall side of our RV began to de-laminate shortly after I purchased. The side had to be pulled off and re glued. They were lucky to get the piece off in one piece........... but that glue did not hold in every place.

Now having a hard time finding the filon with a wood type backing that would help HOLD the new glue against the side.

Has anyone just used metal or wood strips up the side of their unit.... to keep everything together.. could be decorative.

At wit's end and no money to continue extensive repairs.

DIY repair
by: Derek

Try this: hand cut a hole in the middle of the bubble. If it's wet underneath, it will need to dry out before proceeding. Get a large syringe and some tubing to attach to the end. Use the thinnest type of epoxy resin you can find at automotive or hardware stores, then mix and inject in as far inside the laminate as you can reach with your tube extension.

Use a clean paint roller or rolling pin to smooth out the area and also spread the epoxy underneath. Some epoxy may leak back out, wipe it up. You may also use a vacuum cleaner hose attached to your hole at this point to help "suck up" the bubble and get trapped air out.

Place a large, flat piece of wood or something similar against the area and brace it until the epoxy cures, usually a few hours to a day. The fiberglass will now be bonded back to the underlying structure.

2010 399BHS open range
by: Anonymous

I think we were sold a lemon. We have major delamination in the rear bunk house. Its been inspected multiple times by a huge dealer and they can not find the cause. Insurance company won't cover the damage because there is no cause. Does anybody have any ideas. They keep saying they can't find the leak

Can be repaired
by: Mike

I read above comments and felt quite dis-hearted. I have quite a bit of bulging on my RV. Local repairer wanted $5,000 and that was only a part repair.

So I decided to have a go my self most bulging is water egress so chances are you can remove the surrounds of what ever is causing the leak. Mine were mostly windows but below floor line skirting also on one side.

Windows are dead easy to get out and I was surprised amount of wetness around the edges. The glass membrane was able to flap free of the thin ply wood behind and that in turn was free of the foam backing.

I parked it in the summer sun for two days getting all dried out I then bought some adhesive that was quite thin and using a syringe and tube just injected as much as I could into the bulged area. Both sides of the plywood. Use a thin piece of ply to help spread the glue about a bit. I then used G clamps to clamp a solid slab of timber along the edges of the window opening to squeeze the parts up tight then waited a day for the glue to cure.

I won't claim as good as new but gee it's not a bad result and it cost only a little time. Should see the van to retirement.

Put window back in with new sealant in copious amounts so water not going to get back in.

Other areas can be done by removing moulding strips on joints and with the skirting I dropped off the metal channel that capped the edge. Water poured from it but once dried out can be clamed flat. Trick is to dry the area out.

Putting a dehumidifier in the RV for a few days can dry it well as timber inside lining will draw it out. Or just get it under cover for a while.

Check your location.
by: Anonymous

This might sound ridiculous after all the comments about water, but our trailer developed a bulge in the back over the bumper on one side. We raised the feet of the stabilizer and we found that one had become so tight we ended up needing to adjust the front jack down before the back stabilizer would come free and rise. We decided the bulge was not due to water damage or delamination but was due to the ground settling under our trailer and the stabilizer putting too much pressure on one side. After a couple of days the bulge vanished. If it appeared all of the sudden over a short period of time, try adjusting the stabilizers before panicking.

Bulge in RV Wall.
by: Anonymous

I also have a Winnebago with bulges on the side. From what I can tell, the bulging is due to the anchor hinges that hold up my cargo doors on the bottom. Every location where I have a holding clip for the cargo door, I have a bulge. My RV is 13 years old now, Winnebago brave 34 footer. I don't seem to have any leaks on this unit that I can tell, and if I did, it would be a HUGE coincidence that every anchor location has a leak behind it. I just drive my RV and enjoy it all the time, 113,000 miles and climbing! So, if you have some bulging, its not necessarily the end of the world. Don't get screwed out of hundreds if not thousands of dollars for something that maybe more cosmetic than structural.

Walls prone to delamination
by: Anonymous

I have heard mixed commments on what brands delam the fastest due to the use of pinch rolled walls. I am wondering if this is true? I have seen the most delam on all of the Keystone products that are pinch wall rolled and am staying away from them. What else can I look at?

by: Anonymous

what is the solution to the dark decal, hot sun senerio?

Studs or Uni-Body
by: J.M.

I too have bulging at the rear cap, Question is, are the sidewalls constructed with studs?? or a unibody method??
My coach is older mid 90's and have done all repairs myself. The whole side probably need's re-building, But I need a diagram of consturction before I decide to replace or re build. i have the time and pretty good carpenter skills to do the job.
Any help would be greatly appreciated

by: Anonymous

I wish I had of read thist before I bought my motorhome. Well, I may be okay but not sure.. We bought a 1994 Winnebago Vetra 37 foot. We good a deal, I hope.. We paid $4,000 less than any other vectra we saw on the market and about $5,000. under book. The coach interior is in great shape and I mean really great shap. No visible signs of leaking and I hardly believe it was a 1994 because it is in such good shape. It also runs great, has new tires, good running 7000 genset and blew by the inspection.

One problem, it has some delamination, bubbles or warping on the passenger side behind the refridgerator area and just over the water heater. Not real big, but an area of maybe two foot.

We bought this as we were new to RVing and did not want to spend alot of $$$ until we knew we would like it. If we like it, we want to get a newer coach. We only plan to do some weekend trips of no more than 300 mile roundtrip.

Telling you all this, what do you suggest I do?? Do I try to repair it? Do I just drive it and use it for a few years and hope I recover some of my investment when I re-sell it or do I off load it today???

I did not worry about this when I bought it, but because of your post and the possible structure problem I am concerned!! I don't want to go down the road and the whole coach collapse on the frame, oh, and on me.. LOL



by: david

i need a new roof. i found aweb site that sells liquid roof. they say it can be applied over existing roof of my fifth wheel camper instead of replacing roof. what do you know about this.

too late...
by: Anonymous

Ok, I found your site too late. We have already purchased a used RV and now we've noticed the bulge in the side (not even sure it was there before, but has been sitting in the driveway with 40C weather for a couple weeks and it's definitely getting worse). You say it is not a diy project to fix, but we don't have much choice, the money has been spent and because of the age of the beast I'm not sure it's worth spending a lot of money on it. What we do have is time and building experience, so is there any way we can do it ourselves? Beauty is not an issue, function and integrity are all that matter. Thank you.

Comment From RVing Al I will reemphasize my statement that this really is not a do-it-yourself job. Both the interior and exterior skin of the RV can be affected and could have to be replaced. Any mistakes that are made could severly affect the overall strutural integrity of the RV. I would say that you should at least take it to a professional to have them take a look at the RV and see what they recommend.

You are the one that is finally going to have to decide if you can do it yourself or if it is even worth the expense or even your time or labor to fix it. The only way you will know is by having a qualified person look at it.

I hope this helps

RVing Al

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