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Topic: Sealent Tape, Which to Use - Putty, Butyl or PVC

Posted By: Dale.Traveling on 05/15/12 07:15am

I am replacing the awing rails on my coach. The roof is EPDM and is held in place by the rails. As such I will need to seal behind the rails to insure water does not wick up behind the rails under the EPDM and into the coach walls and roof. My choices for sealing tape are putty, butyl, or PVC.

Which should I use?

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Posted By: jhilley on 05/15/12 09:18am

I believe that butyl is a lot better than the putty in the long run. I don't know what you mean by PVC. Silicon would be another option, but once you put it on, it is almost impossible to use something else over it including silicon.

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Posted By: John&Joey on 05/15/12 09:52am

What is the difference between Butyl and putty tape? For me, they are the same thing.

What I would do is forgo the forum and call the maker of the rubber roof to see what they suggest for their brand.

I would also suggest you think of running a bead of Dicor non-leveling chaulk along the topside of the rail once it's all been sealed with the tape.

Last but not least use stainless screws if possible, plus I like to put a little plumbers putty into the old screw hole prior to running the screw back in.

Posted By: Clay L on 05/15/12 10:15am

Butyl putty tape is a lot different from the usual putty tape. It looks similar but is very stretchy.

I have seen two types of butyl tape used on the rails.
One is the light colored Butyl putty tape.

The other is a much firmer (hard to stretch and very hard to pull apart) black butyl tape with an adhesive on one side. I suspect it is used because it can be stuck to the coach making the installation easier.

I would definitely use stainless steel screws as recommended above by John.

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Posted By: Dale.Traveling on 05/15/12 10:48am

Pulled one rail last night and the coach builder used putty tape behind it. The rail came off very easy. I suspect if I use butyl or PVC future removal of the gutter rail isn't going to be as easy as last night.

Stainless hardware is in the plan and sealing the top of the gutter to the roof line also. The hardware I removed was steel self drilling screws and all had a good layer of corrosion. Plan to use sealant on the threads even with the stainless just to get a good water tight seal in the screw hole.

Still wondering what the difference is between butyl and PVC? Local RV supplier has all three.

Posted By: jhilley on 05/15/12 11:02am

Do you have a brand and part number for the PVC tape. It probably is a double sided tape meant for things like molding and trim. The butyl is the best for your application.

Posted By: Dale.Traveling on 05/15/12 12:32pm

jhilley wrote:

Do you have a brand and part number for the PVC tape. It probably is a double sided tape meant for things like molding and trim. The butyl is the best for your application.

Found the missing info I was looking for. The PVC tape is actually a PVC foam core butyl coated tape. From what I could find the foam core adds a bit of flexability and such over solid butyl.

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