Gap between roof and front cap

[msmith1199]

When I first bought my motorhome (12 years ago) I noticed a lot of caulking on the left side of the seal between the one piece fiberglass roof and the front cap. It was obviously that there was a gap there they needed to fill. Over the years I've had a leak problem at the seal and I've added more caulking to it. My motorhome has spent most of it's life indoors so I only see the leak when I'm using it and it rains or when I've washed it, so hopefully not too much damage has been done.

I decided to get up there yesterday and remove all the old caulking and then redo the seam with Eternabond tape. Once I got a lot of the caulking off, I noticed that the gap is bigger than I would have thought. Basically the roof and the front cap come together and on the left side the roof has a slight dip to it. So the roof at the bottom of the dip, is close to a half inch below the front the cap. I can stick my finger in the gap. There is a painted metal trim piece over the top of the seam that is screwed into the roof. The trim piece sits flush on the front cap, but it is up to almost a half inch (maybe a third of an inch) above the roof. I'm pretty sure this dip in the roof had been there since assembly and they just filled it in with extra caulking because I've seen that since the beginning. So it's not the structure or anything under it giving way.

So the question, I'm wondering how to fix it. Ideally I'd like to get the dip out of the roof, but that is not a do it yourself project and I don't even know if a RV body shop could do that. So I'm contemplating other fix ideas. I'm thinking about removing the trim piece so I can completely see the seam between the two pieces. And then filling in any gaps somehow with the trim piece off, and then putting it back on re-caulk and then put the Eternabond over the top and double or triple it up in that area? It's pretty obvious that when they assembled the motorhome they fitted the fiberglass pieces and then put the trim piece on without any caulking underneath it and then caulked the joints as the last step. So I'm thinking if I get it good and sealed underneath that I can make sure it doesn't leak again.

Anybody got any better ideas?

[msmith1199]

That is one thing I'll look for in the next motorhome is a one piece roof that curves down on all sides. Then once I buy another brand new motorhome I'll go up and remove all the vents and everything else on the roof and reinstall them correctly. That is assuming I can't afford a Prevost by the time I'm ready for the next motorhome.

[mike_brez]

That is a terrible pic but there is no seam. The lighter colored area has a diamond texture on it for non slip traction when up on roof the rest is smooth.

[msmith1199]

That's exactly what I'm saying. All one piece fiberglass roofs should be like that. I didn't know they made one like that and your front seam doesn't standout as much as I thought it would. As long as there is a lip for the roof to overlap you should never have a leak problem even if the sealer does fail as gravity would keep the water out.

[mike_brez]

Not sure what you are saying ours is one piece. This is the only pics I have.

[msmith1199]

mike brez wrote:

msmith1199 wrote:

mike brez wrote:
A one peice fiberglass roof :R

Are you asking? Yes, it is a one piece fiberglass roof.

Guessing

Yes it is and I love the fiberglass over the rubber. The only problem has been the seam. It's too bad that they can't make the front and back of the roof similar to the sides and have it curve over the front and back ends. Basically make the curved top part of the front and back of the motorhome part of the roof versus being part of the end caps. It wouldn't look as good since the seam would be more visible, but it sure would stop a lot of leak problems.

[mike_brez]

msmith1199 wrote:

mike brez wrote:
A one peice fiberglass roof :R

Are you asking? Yes, it is a one piece fiberglass roof.

Guessing

[msmith1199]

mike brez wrote:
A one peice fiberglass roof :R

Are you asking? Yes, it is a one piece fiberglass roof.

[mike_brez]

A one peice fiberglass roof :R

[msmith1199]

It would have been very simple for National RV to have added some solid wood or hard wood backing where this seam was and then used longer screws to bite into the solid wood. Would have probably cost them $25 per motorhome, which would have included labor, to do this and would prevent a lot of problems for a lot of motorhomes down the road.

But the good news is I learned a lot about motorhome construction from those so I'll know some things to look for if I ever get another one.

[msmith1199]

Neither really. I just assumed the fiberglass was much more rigid than it actually was. It's pretty flexible. If you go back a few posts you see I determined the screws were too short and weren't even holding in the wood underlayment. So basically the only thing holding the front cap to the roof was the sealant. And I know it was like this since it rolled out of the factory because I always know they corrected their mistake with giant gobs of self leveling caulk. Whomever put the screws in probably did so with a drill driver or air driver and just torqued them in and stripped out any grip they may have had. So the play in the fiberglass immediately pulled the screws back out on that side. And they would have pulled it out on the rest of the seam but the caulking dried enough to hold them in.

[rgatijnet1]

Did you ever figure out if the front cap was bowing up or the roof was sagging?

[msmith1199]

Something to note in my photos, the AM radio antenna was already there, but the Satellite dish was something I had added quite a while after I bought the motorhome. I originally had a Kingdome dish and I replaced it with the HD dish. Although they installed the new dish close to the same spot, they put it right up against that front seam. That just made it more difficult to do this job. Also instead of using the old coax route which entered the roof aft of the dish, they ran the new cables up to the front cap and then down into the cabinet and as you can see also put that mount right near the seam. If I had known in advance I was going to redo this seam, I would have made sure all those extra items were mounted no closer than maybe 6 inches to the seam. Would have made fixing the seam that much easier.

[gonesouth]

Good job!

[msmith1199]

mike brez wrote:
I know that tape is suppose to be the best thing sence sliced bread but it looks like a giant band aid.

Looks don't matter much when it's on the roof and you can't really see it. I'm just hoping it works as advertised.