Very Poor Results From Heng's Roof Coating

[solismaris]

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.

[BurbMan]

solismaris wrote:
I did what I thought was a thorough cleaning: detergent, rinse, thorough wipe down with acetone.

This is the problem, right here.

[C_Schomer]

I made a similar mistake with mineral spirits. I was trying to clean every last bit of old caulk off of a small area and the mineral spirits rippled up the rubber membrane. I waited about a week and the ripples flattened out and the membrane look normal. The local trailer repair shop near me told me not to use Hengs and a local commercial roofing supplier told me to use Henry’s. I’ve done two RVs with Henry’s and I pressure washed to remove anything that would possibly break loose and then I used a Scotch-Brite pad and TSP solution to clean the membrane. I used Henry 587 on a previous RV when I lived in the Phoenix area and it still looked awesome after five years of outside storage, when I sold it. I used Henry 787 on this fiver two and a half years ago and it still looks like new, too. If I ever do another one I will use the Henry 887 which is 100% silicon and it is recommended for RVs. I’ve had zero problems with the cheaper Henry products though. Craig

[Veebyes]

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?

Using Acetone is my suspicion also. Acetone is one powerful solvent. I use it everytime doing fiberglass work but would never consider using it on a rubber roof.

I did my roof a couple years ago on my 2007 5er. It had 'roof pox', the black spots but it was in decent shape.

Cleaned it with a regular car wash soap. Gave it going over with 50% clorox & water in an effort to kill the roof pox. Let dry then rinsed it off.

Rolled on two coats of Hengs Tropicool & it has been looking good ever since.

[Thermoguy]

Good Luck getting it off. Mine was done before I bought it. It has been peeling off ever since. I'm not sure how it was prepared or done, but done by the dealer as a way to extend the longevity of the roof. The guy I bought it from showed me a couple places it was coming off so I would not be concerned there was a problem with the roof. When I had the RV inspected, post purchase, the guy told me that is what they did and to take the coating off over time. Every year when I clean the roof I get more off. Peels in large or small sections. Now it's mostly off. I have thought about applying something like this but a post like this makes me think twice. My repair shop says don't do it. I want the roof to look better, but it doesn't leak so I guess it still works. Putting a new roof on is just a huge expense and no guarantees how long it will last. Other coatings sound good but too expensive considering to be just a coating. Anyway, good luck getting it off good enough to recoat.

[rhagfo]

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.

I have never been a fan of Eternabond for sealing vents or other roof penetrations. That is what Dicor self leveling caulk is for. I know Eternabond tape is super sticky, but putting tape over irregular surfaces just doesn’t make sense to me. I see it as great for an emergency fix to the flat rubber surface, but not over screw heads, and uneven surfaces.

[agesilaus]

they do say clean with acetone

I believe, and I'm no expert, that acetone use depends on the type of roof. Some are OK to use it on, others not.

[solismaris]

Guess a redo is in my future. No acetone next time. But I rechecked the Eternabond site and they do say clean with acetone prior to applying their product so I was not concerned about damage to the roof. I figured the acetone after it dries would not affect the Hengs but it somehow did. Or maybe I was not thorough enough with the scrubbing. So no more acetone next time, wait for a Very dry weather period, use powdered detergent, good scrubbing, good rinse, dry a long time, then try Heng's again. Wish me luck!

[larry_cad]

I just chatted with Kim at Heng's customer service, and this is what she wrote to me regarding roof preparation:

"Yes, it would be due to the acetone is why it is coming off. The only thing we recommend for cleaning is a powder detergent such as Tide, Spic and Span, or Ox clean."



Thank you,



Kim Grantham

Customer Service

Heng’s Industries

(574) 295-1200

[agesilaus]

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?

My thought too, I thought acetone was specifically NOT to be used on rubber roofs. What do the instructions on the can say?
I used Hengs on our 2006 roof, went on easily and has held up well. Roof prep is the key.

Proper Prep Prevents P* Poor Performance.

[Lwiddis]

Sorry to hear of the roof issues. I’ve had nothing but success with Heng’s.

[rhagfo]

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.

[solismaris]

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.

[larry_cad]

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?

[NamMedevac_70]

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.