Fiberglass Roof Repair

Soon after we bought our Newmar, I climbed up on the roof to check what shape it was in. I discovered that my Newmar fiberglass roof was constructed differently than the fiberglass roof on our previous RV, a 2004 National RV SeaBreeze.

Newmar’s Fiberglass Rectangle

While the SeaBreeze roof was a solid piece of fiberglass, the Newmar roof was a large rectangle that was screwed and glued to the top of the RV.

I was less than thrilled. It seemed like this was a roof that could easily leak so I decided to “beef up” the very long roof seams.

This was a mistake.

It was a mistake because I used the wrong caulk (Sikaflex 512UV) and then ran Eternabond tape over all the seams. Sikaflex was the wrong choice because this sealant is not “self leveling” — it retains its shape and doesn’t flatten out.

So the Sikaflex dried in the shape of a continuous hump that ran the entire length of the roof seam. I should have removed it, but I put Eternabond tape over all the Sikaflex.

Sikaflex Hump

When I checked the roof the following year, I discovered that the Eternabond tape had “tented up” over the Sikaflex caulk. It was also apparent that the tape was not sticking to the caulk.

In October 2012 I decided to do it right. First, using a heat gun and plastic scraper, I removed all the Eternabond tape. I actually was able to physically pull off much of the tape. However, even in areas where the tape has separated from the caulk, the Eternabond greatly resisted removal.

Note that when Eternabond is removed with a heat gun, much of the tape’s adhesive (butyl rubber, I believe) will remain on the roof. This is ok as Eternabond sells a primer that is sprayed on the adhesive just prior to laying new tape.

Eternabond Tape/Adhesive Tests

Second, after removing all the tape, I scraped off much of the original painted sealant from around the entire fiberglass sheet on the roof. I did this because I noticed some areas of the roof had bulged up indicating possible water damage. This turned out to be the case. I had to glue and screw several places where the fiberglass roof had warped because of water penetration.

Before selecting another roof sealant, I ran some tests to see how well Eternabond tape adhered to several types of adhesives and sealants.

My “scientific” results:

• DAP Premium Silicone Rubber — No Stick. This silicone-based product should be no surprise. Just say no to silicone.
• Loctite PLS30 Polyurethane Sealant — Good Stick. The PLS30 is still rubbery after 5 months.
• Dicor 501 LSW Lap Sealant — Great Stick. Dicor is the one to beat. The product I was using is self-leveling which means it will flatten out. Dicor also makes a non-self-leveling version.
• Loctite PL Premium Advanced Polyurethane Adhesive — Little Stick. Great if you’re laying a subfloor, but would not recommend this for an RV where there is movement.
• Loctite Power Grab Adhesive — Good Stick. This is another home-construction type adhesive.
• White Lightning Butyl Rubber Caulk — Great Stick. This was a surprise. When I tried pulling off the Eternabond, the White Lightning came with the Eternabond. However, the White Lightning had the least surface adhesion of all the products I tested. This butyl rubber caulk could be pulled off the surface fairly easily — but it did become ONE with the Eternabond tape.
• Sikaflex 512UV Polymer Sealant — No Stick. By itself, Sikaflex is a great sealant, but Eternabond doesn’t stick to it.
• 3M 5200 Marine Adhesive Sealant — Great Stick. This stuff could have saved the Titanic. Zow! A sealant and adhesive. However, it takes at least a week to cure. Solution: 3M 5200 Fast Cure (24 hours).

Here are my fiberglass roof repair photos . . .

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