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Open Roads Forum  >  Tech Issues

 > Very Poor Results From Heng's Roof Coating

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solismaris

Massachusetts

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Posted: 02/20/22 06:56pm Link  |  Quote  |  Print  |  Notify Moderator

Heng's rubber roof coating is the most recommended roof coating in this forum, and has very good reviews online. So I decided to try it for my aging rubber roof (16 years) which was still intact but starting to show a lot of black underlayer.

So on a warm dry day last May I did it. I did what I thought was a thorough cleaning: detergent, rinse, thorough wipe down with acetone. Applied 2 coats Heng's with brush. Let dry. Next morning looked great. The whiteness was actually shockingly bright.

But looks are deceiving. By day 2 I saw evidence of lifting in several places. Not small bubbles, but large areas of a square foot or more just lifting like a rubber sheet. So the coating is strong and loves to stick to itself but it is just terrible at sticking to the roof! What could be wrong?

Nothing I can do now except strip it all off and start over. I haven't done that yet as I wanted to see how long it lasted. Not long it turned out. Over the course of the 6 or so camping trips last year I witnessed pieces tear off one by one until at this point about half of it is gone!

Stripping the rest should be easy, I think it will peel off in big chunks. The question is what to replace it with? Unless I did something seriously wrong with the prep then Heng's is out. ProGuard? Dicor? Don't laugh but I am thinking of covering the whole roof with Eternabond - they do make it in 24" sheets. I've never had problems with Eternabond sticking.


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garyemunson

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Posted: 02/20/22 07:01pm Link  |  Quote  |  Print  |  Notify Moderator

A 16 year old roof is done. The coating stuck to the surface it was applied to, the surface just pulled away from the substrate. Anything you put on it will do the same. Replace the roof membrane.

TurnThePage

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Posted: 02/20/22 07:23pm Link  |  Quote  |  Print  |  Notify Moderator

I dunno if I agree with the above. My roof was 14 years old with lots of black rubber showing. It's been almost 4 years and my Hengs roof is holding up well. OP, sorry to hear about your experience.


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bmwbob

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Posted: 02/20/22 07:25pm Link  |  Quote  |  Print  |  Notify Moderator

I redid the rubber roof of our (then) 10 yeR old DSDP with the product from Minnesota RV Roofing.
13 years later, now with new owners and no problems at all.
Highly recommended!
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rhagfo

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Posted: 02/20/22 09:11pm Link  |  Quote  |  Print  |  Notify Moderator

Sorry I don’t see how you can completely and correctly apply Heng’s in a single short day. I took three days to apply ours. Weather was clear and dry and daily temperatures were 80 to 85 degrees.
Day 1
Removed all our MaxAir vent covers and cleaned all vents.
Swept roof very well.
Mixed a strong solution of powered Tide detergent and warm water and scrubbed a 3’ X 3’ section with a medium stiff scrub brush, then rinsed with lots of water.
Once entire roof was washed I rinsed again, and allowed to dry overnight.

Day 2
Waited until about 10:00am to start edging around all vents, AC, and bath skylight.
Used a short nap roller to apply, worked on well and a thin coat. Not sure if I needed to open second gallon to finish first coat on day one.
Allowed first coat to dry overnight.

Day 3
Applied second coat edged the entire edge of roof again with brush, then rolled on second coat again. This was allowed to dry overnight.

I think using the acetone was likely a mistake, as Heng’s is an water based product.

Ours is doing very well, as I used just under 2 gallons, I am considering adding two more coats this summer.


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rhagfo

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Posted: 02/20/22 09:26pm Link  |  Quote  |  Print  |  Notify Moderator

garyemunson wrote:

A 16 year old roof is done. The coating stuck to the surface it was applied to, the surface just pulled away from the substrate. Anything you put on it will do the same. Replace the roof membrane.


I agree with Turn The Page, the roof is not in need of replacement. Our 5er is a 2005 with the original roof. I just believe the OP rushed the application, especially the time from cleaning to application.

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Posted: 02/21/22 05:10am Link  |  Quote  |  Print  |  Notify Moderator

For many years I had excellent results with DICOR Rubber roof. Still like new when I sold the TT (15 years). Cheers to RV-Vision Trail Cruiser.

larry cad

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Posted: 02/21/22 05:41am Link  |  Quote  |  Print  |  Notify Moderator

rhagfo wrote:


I think using the acetone was likely a mistake, as Heng’s is an water based product.



21 years old rubber roof with Hengs and no lifting. I agree, why did you use acetone?


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solismaris

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Posted: 02/21/22 05:57am Link  |  Quote  |  Print  |  Notify Moderator

larry cad wrote:

rhagfo wrote:


I think using the acetone was likely a mistake, as Heng’s is an water based product.



21 years old rubber roof with Hengs and no lifting. I agree, why did you use acetone?


Ok, no acetone next time. That is what was recommended for Eternabond so I thought that would be right for final cleaning before applying Heng's. But people seem in agreement that I rushed the job or screwed up the prep. I'll study the Hengs instructions carefully and try to contact somebody at the company for advice. And I'll do a sample area first and give it a month to test it.

No I didn't do it all in one day. More like 3. But it was somewhat faster because I did not remove any roof structures like vents because they were already well protected with Eternabond so I only recoated up to the Eternabond or slightly beyond.

rhagfo

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Posted: 02/21/22 06:30am Link  |  Quote  |  Print  |  Notify Moderator

solismaris wrote:

larry cad wrote:

rhagfo wrote:


I think using the acetone was likely a mistake, as Heng’s is an water based product.



21 years old rubber roof with Hengs and no lifting. I agree, why did you use acetone?


Ok, no acetone next time. That is what was recommended for Eternabond so I thought that would be right for final cleaning before applying Heng's. But people seem in agreement that I rushed the job or screwed up the prep. I'll study the Hengs instructions carefully and try to contact somebody at the company for advice. And I'll do a sample area first and give it a month to test it.

No I didn't do it all in one day. More like 3. But it was somewhat faster because I did not remove any roof structures like vents because they were already well protected with Eternabond so I only recoated up to the Eternabond or slightly beyond.


Well the best I can say see if you can get to a time when it is warm not only during the day, but also over night and low humidity. We full time and were hosting in the Columbia River Gorge and did ours in late August. The only process I started early was the scrubbing of the roof. That was a hands and knees job, with a medium stiff scrub brush, seemed like it took a long time to do the roof on our 32' 5er.
The other thing I did was once the roof was scrubbed, and I was edging and coating, I never wore shoes during the application. I had a clean mat at the base of the ladder, and would only work in stocking feet.

The hardest part was going four days without using the AC in 80+ degree temps.

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