Community Forums

**Spdracr39** · 05-01-2019, 06:43 PM

The fiberglass roof of my coach was previously sealed with an unknown product. They put it on thick, I would guess brushed, over the original sealant that was very cracked up. I think the original was probably Dicor. This stuff is clear and rubbery. You can see all the old cracks but they are mostly sealed. there are some places that the clear sealant is failing and I tried to use dicor but it just peels right off after it sets up. Any ideas on what this sealant may be and what else might stick to it? I hope it isn't silicone :( I have never used proflex so I don't know what it looks like. Would Dicor stick over it ? Will Proflex stick to things Dicor won't ?

vettenuts · 05-01-2019, 07:20 PM

Sounds like silicone based on your description. The Proflex looks somewhat like silicone but is stiffer when you feel it.

**Spdracr39** · 05-02-2019, 05:08 AM

Ok thanks. It feels more like rubber than silicone. All I know to do before completely removing all of it is to try a little proflex on it and see what happens.

vettenuts · 05-02-2019, 10:09 AM

I have a similar issue with mine. The previous owner sealed the joints with something that has gotten hard over time and has developed some small cracks. I thought about full removal but that would likely damage the roof. I thought about covering with a wide single piece of Eternabond tape, but I would need to get the prior sealant smooth and leveled more than it currently is on the roof. I have been hitting the cracks with Dicor Lap self leveling sealant for now while I sort out what else I can do. I don’t think the cracks in the sealant put on by the prior owner would leak, but don’t want to risk it.

**Spdracr39** · 05-02-2019, 01:11 PM

I believe it is proflex. I found some video of the brush on application and it is exactly what it looks like. I am going to get some and brush it over it and see what happens. If that doesn't stick it will be a complete removal and reseal.

lonfu · 05-02-2019, 02:14 PM

there are 3 different kinds of roof sealant. 1. butyl 2. latex 3. silicon

Butyl makes a good compression caulking, like dicor or the cheaper big box store brands. $7 and $2 respectively. It is affected by UV rays and will dry out. Should last at least 5 years exposed 15 years not exposed.

Latex roof caulking is UV resistant and can be used for either compression or coating the edges of a roof vent/jack. It can last up to 15 years. Latex Roof coating in a can can be brushed on from a can and make a fine surface seal. How long it lasts depends on the $$ spent on it. Works on fiberglass and aluminum roofs. Not for TPO or EPDM roofing.

Silicon is now made in a roof coating as well as the caulking we are use to using. Silicon roof caulking can be used as a compression as well as a roof jack/vent edge coating. Roofing silicon is not joint and trim silicon!!!! it is much more expensive and UV resistant. You will find it only in the roofing dept of your local big box store. It ain't cheap!!!! plan on at least twice as expensive as regular silicon....for the good stuff... Dicor is not roofing silicon...Silicon roof coating is designed to permanent!!!! it is a PIA to clean off once installed but is easily repaired....I've used silicon roof coating on TPO and rubber roofs with perfect results. It works on fiber glass and aluminum too...

Then new tech has changed the roofing industry.... Called "roofing tape"... it is usually some sort of buytl coating on either a plastic back like "etranabond tape" or aluminum backing on the big box store stuff (1/2 the price). Same stuff, all about name on it. I've used both and don't see an diff..... it is used to cover the edges of a roof jack/vent after installing a compression gasket of what ever you want. Butyl, latex or silicon... Most roofing guys don't like call backs, so they use the cheapest caulking, usually butyl for the compression gaskets, then tape the edges of the vent/roof jacks with 6" tape.... the thing that is cool about the roofing tape is that you can then match an existing roof coating....Manufacturer's don't like roofing tape because it is expensive and labor intensive to install.

What you can't do is mix caulking types.... latex does not stick to butyl, silicon does not stick butyl, silicon will stick to latex but not recomended, butyl will stick to silicon and latex for a short term but I wouldn't waste time with trying that. So, I'd clean all of the exposed caulking of the edges of your vents, don't pull them, then install roofing tape over the edges all the way around the vent, then coat the tape with your choice of roof coating... I'd recommend silicon roof coating if there is not a current roof coating. If there is then you need to match which coating it is and coat the tape past the edges.

The other rule of caulking is when installing new, remove all the old..... down to the hard surface... yep, it is hard work scraping and chemicaling off the old stuff.... start with paint thinner, then go to carb cleaner/laquer thinner. Put the stuff on a rag don't just dump it on, use abrasive's to help.... sandpaper, scrub pads stuff like that.... It will take a while but you can get it off....A lot of RV techs don't like cleaning the old stuff off so they will skip this step, try to match the caulking type and in a few years you will have the same problem all over again...

Roofing tape sticks to latex roof coating. I've never tried sticking it to silicon roof coating with our removing the coating first, laying the tape, then coating the tape with silicon roof coating.

Been doing this stuff for a while, 1980, and understand that this is just my opinion of these chems and what I've seen over the years that lasts and what doesn't....