Roof bubbling

[Topglock]

After a recent roof inspection I noticed the fridge vent lid was very brittle. Ordered a new camco lid that would not line up to my Atwood base. I had to also replace the base with the camco brand. After sealing it all up with Dicor/butyl tape the edges all bubbled up,one spot so much it was touching the lid. I know this topic has been beat to death but WTH! Do I leave it be? I don’t really want to pull the base back up if I don’t have to.

[Mmeyer]

Mine did the something but went away it in a week or so.

[JRTJH]

I would guess you used DICOR self leveling sealant on the roof ???

If you did, chances are that it's the "original forumla" intended for EPDM roof membrane not for TPO roof membrane. The difference is the amount of solvent mixed into the sealant. Original has more solvent, intended to "soften the membrane so the sealant can fuse with it. EPDM requires more solvent than TPO.

Your roof is TPO, using the "high solvent content sealant" will cause the membrane to "soften too much" and to bubble or disfigure... It's cosmetic, does not affect the TPO membrane function, and, in most cases, will resolve on its own as the solvent evaporates from the sealant as it cures....

Next time, look for Alpha Systems "low solvent" sealant or for DICOR Low Solvent sealant. Both are "formulated for TPO roofing membrane.... The original DICOR is formulated for EPDM roofing membrane...

[Topglock]

Thank you! I had no idea there was a old and new formula. Learn something new everyday.

[NH_Bulldog]

I am more inclined to think the issue might be the putty tape as opposed to the Dicor sealant. There is inexpensive putty tape that runs under $10 or less for a 30’ roll but it has a high level of solvent that will damage the roof membrane and cause bubbling like you are seeing. Covering it with Dicor only traps the solvent and makes it worse. There is a good butyl putty tape that is compatible with the roof membrane (Dicor is one brand) and those types run $20+ per roll. There are no issues using either tape on sidewalls, windows, doors, etc. but with roofs you have to be extra careful.

I would keep a VERY close eye on that project area and if it doesn’t get better soon, consider Plan B.

[Topglock]

I am more inclined to think the issue might be the putty tape as opposed to the Dicor sealant. There is inexpensive putty tape that runs under $10 or less for a 30’ roll but it has a high level of solvent that will damage the roof membrane and cause bubbling like you are seeing. Covering it with Dicor only traps the solvent and makes it worse. There is a good butyl putty tape that is compatible with the roof membrane (Dicor is one brand) and those types run $20+ per roll. There are no issues using either tape on sidewalls, windows, doors, etc. but with roofs you have to be extra careful.

I would keep a VERY close eye on that project area and if it doesn’t get better soon, consider Plan B.

Yesterday was a week since I installed the vent and it still looks the same. The butyl tape I used was Camco 25013. I tried to do some research on it but all it says it’s safe for rubber roofs. Not which ones.

[JRTJH]

CAMCO butyl putty tape is perfectly safe to use on TPO or EPDM roofing. In fact, it's marketed as a "vent replacement kit" specifically for TPO or EPDM roofing material.

If the issue wasn't "mechanical" (you pulled the TPO and caused it to pucker while you were screwing the base plate down), the only potential issue is the type of sealant.

If it were me, I'd go camping rather than worry about the roof bulge. It's not a problem and if it gets worse, just buy some "low solvent sealant" and dab on another "bead of sealant"...

Taking it apart will probably cause more damage than leaving it alone....

[Wyldfire]

In the future just use Alpha as most TPO roofs are made by Alpha.

From Dicor:

https://dicorproducts.com/62/