How to glue your Winnebago roof back down

As I previously mentioned, the roof on our 12 year old Itasca Sunrise almost blew off.

We’ve owned this rv for a year. We did have it inspected before we bought it from a private seller, but clearly this was missed. I do distinctly remember our inspector telling us that the roof was extremely well sealed, that “typically, you see this dinky amount of caulk, but there was just– so much of it up there. Gobs.”

There ARE gobs of caulk over all the rooftop fittings, but it is almost completely worn away along the sidewall seam, where the thin fiberglass roof is glued to the gutters. Which explains why the roof popped almost entirely along one side. If either of the corners had popped, the entire roof would probably be gone, leading to an extremely expensive roof replacement bill, in the thousands.

Luckily, that didn’t happen, and we just need to remove all the old caulk, clean it up real well, and apply new caulk. Not difficult, but tedious work.

Here’s a diagram from Winnebago:

(Source)

Materials

Winnebago reccommends inspecting this adhesive caulk TWICE A YEAR and filling in any missing patches. The product is a urethane-based adhesive sealant called Manus 75-AM.

It’s a little hard to find as few places stock it. If you do find it in stock, check the manufacture date as this stuff expires within nine months! After expiry, the adhesives won’t be as strong. We ordered 3 tubes from the manufacturer through a local adhesives & sealants shop. $5 a tube, to arrive from Minnesota within 4-5 days.

Surface Prep

The most arduous step in this entire process was prepping the surface. These are the materials I used to scrape all the old caulk off (where there still was some):

• Cleaning bucket filled with water + a little bleach and detergent
• Automotive sponge for general cleaning of the area
• Scrub brush
• Various plastic scraping tools such as putty knife and caulk remover
• Ladder (thanks Uncle Victor!)
• Hose

I started by generally cleaning the roof area with the sponge, then alternating scrub brush and scraper with blasting the inside of the J-rail with the hose. I also cleared out the weep holes on the J-rail, which were clogged with all sorts of debris.

While waiting for the caulk to arrive, I duct taped the roof back down. I had much better adhesion with this All-Weather white duct tape vs the standard duct tape. Bonus: the white color made the temporary repair look slightly less… duct taped?

Application

It was like Christmas morning when the Manus caulk arrived. We were so excited to get the job done that… I forgot to take photos. Woops! But here she is a month later, after getting nice and dusty:

The application went really fast, and was pretty easy. I used these materials:

• Manus caulk (obvs)
• Caulk gun
• Caulk tool
• Paper towel, for wiping excess caulk off the caulk tool
• Ladder
• Spray bottle filled with 50/50 water and blue Dawn soap

The spray bottle was key. The sealant product requires moisture in the air to cure, and Manus recommended at least 40% humidity for curing. Unfortunately, Albuquerque hovers around 10% humidity, so Manus suggested that we spray down the caulk with the soapy water before smoothing. This both helps the product cure AND makes smoothing it down less of a mess (that’s where the Dawn comes in).

Eugene and I worked as a team, him wielding the caulk gun and me following with the spray bottle and caulk tool. It was all done within an hour.

Within a couple days, the product was cured and the duct tape came off.

Lessons

In hindsight, this was a pretty easy repair job, once we understood the scope of work. Given that I already had access to the rest of the materials, the $15 and two days I spent on this certainly beat the $7500 quote I got from the one repair shop I called for a quote. They wanted to replace the roof with a rubber one, likely taking weeks to complete. “Insurance will cover it,” they said. Thanks but no thanks.