Roof sealant

[DrDaveCA]

I was up on the roof yesterday and I see that the sealant used where the roof joins the front and back shells if getting old, it is drying up and cracking . Before it starts to leak I want to renew it. Has anyone had to do this yet and if so what did you use? I know the roof and shells are fiberglass so I am thinking of using a good grade silicone sealant, any advise?

[az bound]

Silicone sealants are not the best choice, If you are looking to just reseal I would recomend Dicor self leveling caulk. Clean the existing caulking with acetone or remove the old caulk as much as possible and clean before applying.
Another method that many are using is to remove all of the caulking and apply Eternabond tape. Many are removing the trim that covers the joint at the roof and end cap and installing the tape under the trim.
The problem with using silicone is that when it has to be resealed all of the old sealant will have to be removed becauce nothing will adhere to it, not even silicone.

[EngineerMike]

Dave- also check your longitudinal seams where the roll of the roof meets walls on long sides. That seam can develop splits in the sealant that will wick moisture into the roof. for those I'd recommend Acryl-R SM5555 by Schnee-Morehead. You have to remove as much old sealant as possible, which is tedious, clean & dry the joint. I apply blue masking tape (3M) to achieve a clean trim edge, but even w/that the superior grab of the Acryl-R will make some fine strings when removing the tape; its pretty sticky, viscous stuff, which is why it lasts better than the stuff off the shelf at C.W.

[takepride]

Dave:

I just used a plastic spatula to peel the old stuff off. Once you get started it goes pretty fast. Acetone will clean it up. I used the Dicor from CW, for lack of a better choice. I'd be willing to try others. (Note that I had to use a steel spatula on other parts of the roof, as the sealant was incredibly hard.)

As the cap rolls over the edge, you will want to use a clear sealant, as it is VERY visible from the ground. Most folks do use silicone there. Just be sure to do a very good job cleaning it up first. And don't remove your paint with the Acetone or lacquer thinner, by accident.

The job took about 40 minutes per cap, since I'm a very slow (but thorough) worker. It is a hobby after all.

eMike:

Is that sealant clear?

[EngineerMike]

I may have the product# wrong. I'm finding 5555, 5522c or 5522p and 8500 on further searches. I'll have to check the tube at home to see which one I actually used.

The 5522 stuff comes in "C" for Clear & 'P' for Pigmented. The stuff I used was "clear' which means clear when coming out of the tube, but drying to a slightly brownish sort of clearish. If you know what I mean. Looks like silicone w/out the blue-ish or white-ish. It also remains really pliable. Data sheet says 100% elongation which is way more than we need. Google: Schnee-Morehead and click on Products for more than you want to know.

[jerry and toni smith]

EMike, Thanks for the tip on the blue tape. Just caulked the floor seam with marine removable silicon and it looks real good. Bet the trim wont fall off either.

Jerry Smith 34 2006

[Wayne R]

EM, I found Acryl-r SM5504 at RV Truck Parts - RV Parts & Truck Tow Accessories . No luck finding 5522 other than data sheets and 5 gallon pails.

[EngineerMike]

I have 2 spare tubes of 5522C (clear) out of 3 I ordered. That's what I used to redo side roof seams. I got it from some east coast internet outfit.

I tried the tape trick when caulking a tub once after making an engineering mess the first time. The tape made an idiot into a serviceable caulk applicator. Tape takes only a few minutes to apply, and if you goof up, you can smooth a section over w/out pushing caulk all over adjacent surfaces. Tape both sides, remove immediately after caulk is applied & smoothed.

[Old Rv'er]

All - I might add that if you wet your finger, and lightly rub over the applied material, you can smoothe out the bead, and it will also break the surface tension, and stick better. I have used 30 year outside Silicone for all seam repairs in the past, the only drawback was it yellows over time. Mike knows the best stuff to use, please let us know how it turned out and any "help-too's" you can give us.

[glacier]

I have two cracks starting at the longitudinal seam and continuing over the top of the roof line. Both were repaired ,by the dealer, using some type of tape. Don't know if that is the proper method of repair? Was wondering if one of these products would be a better fix?

[Wayne R]

I finally found a source for the 5522C sealant.

Lake Country RV Sales & Service-ACRYL-R® SM5522 ACRYLIC SEALANT

[EngineerMike]

Wayne- that's probably where I bought 3 tubes. That's a good price; I remember most folks wanted $17/tube, but this outfit was way cheaper.

In retrospect, one tube will do the whole roof, both sides, plus this stuff will work to go over any suspect self-leveling caulking that may be splitting or otherwise suspect, so one tube will do a full side-seam plus patch job. The tubes I have show Mfg'd 5/10 and Exp 11/11, so there is a shelf life. I'd probably only order one tube, and then order another when I'd used that one. At least one of mine will go out of date if I only use them on my rig.

[Tom and Patty]

I thought 3M 5200 was the sealant to use?

[EngineerMike]

5200 is their marine permanent sealant. I've used it on top of the roof for coax entry, and I've used it on the outside of the new super-flex drain pipe for kitchen sink at the main slide. Its good stuff.