Recommended Butyl Tape And Sealant For Installing A MaxxAir RV Roof Vent

Question:

When installing a Maxxair roof fan/vent, what size butyl tape and sealant around the vent do you recommend?

asked by: Steve W

Expert Reply:

I recommend the Alpha Systems Butyl Tape for RV Weatherproofing # AL28FJ as it's 1" wide to fully cover the flange of your vent. Make sure you overlap the ends to form a tight waterproof seal. You can see me doing this at 2:50 mark in the attached video below.

As for the sealant, I recommend the Alpha Systems 1021 Self-Leveling Sealant for RVs # AL98KV. One tube of this will be enough to fully cover the screws and layer it down to the roof to ensure you don't have a water leak.

expert reply by: Kevin C

Jake

5/18/2024

This Alpha systems tape and caulk is different than the kit your website links to, for install of the delux fan. Why the difference? Which is better and why? Thank you -

Kevin C.

5/20/2024

@Jake LaSalle Bristol is the other option that we offer, which is most likely what you're seeing in the kit. From firsthand experience I'd say the Alpha Systems butyl tape # AL28FJ is better than the LaSalle Bristol butyl tape. It's less tacky and cooperates without making a mess. For the sealant I've changed my opinion recently and prefer the LaSalle Bristol # 34427034145-1. The last couple of tube from Alpha that I used were super tacky and didn't want to spread smoothly so I was kind of disappointed in the finish. LaSalle's has always spread smoothly for me and came out looking great. I believe a majority of the issues I was having was simply because of temperature though. I was working in a hot shop/outside in 90+ degree weather so both the tape and sealant were hot. If you're going to work in hot weather and the tubes/butyl tape are going too hot you'll likely run into the same issues. If you don't have a cool place to store them then you can throw them in a fridge or cooler for a bit before using them to make your life easier.

Jake

7/15/2024

@KevinC Thank you, I plan to put whatever tape I go with, in the freezer before working with it. Another clarifying question I had is about the width. Many reviews of Butyl include that it pushes out as the flange compresses it and so I wondered if the Lasalle Bristol would end up compressing enough to fill the whole flange width and if the 1" Alpha version would lead to excess trimming, as it starts to "ooze," (many suggest letting it ooze over days, and keep trimming at the flange edge, before applying self-level or lap sealant). Thank you -

Kevin C.

7/15/2024

@Jake Butyl tape like the Alpha # AL28FJ has more of a thick gummy, but not sticky, consistency and doesn't ooze out. The tape does compress and squeeze out sort of like modeling clay but you can easily smooth/remove it from the flange with either you finger or a composite trim panel tool # PT73HJ. You should have no issue using the butyl tape and immediately using some sealant. If your butyl tape oozes then I would question the quality of the butyl tape.