Urethane Adheisive Caulk

Question

I am sure that this question has been ask here sometime in the past, but I was wondering if anyone has used urethane construction sealant to seal up body trim and utility ports (water fill flanges, cable port flanges, external shower doors, etc), on fiberglass sided RV's?  I know that it shouldn't be used on rubber roof's and such, but I am having a problem with the access door for my outdoor shower and city water connection port.  The curvature of the body and the weight of the water hose  has allowed the flanges to leak when the factory seals that used butyl rubber tape and what appears to be a clear automotive joint sealant gave out.  I have used the urethane construction sealant many places on the outside of the house over the last 10 years and have not noticed any cracking or separation and the sealant remains flexible.  It is a mess to put on, so I will have to mask the application sites to avoid a lengthy cleanup. Any thoughts?

rvpapa · Answer

Better than anything else. If there is already butyl caulk , clean as much away as possible. The solvents in the butyl will try to lift from under. Black has good UV protection but white seems to require cover. I run a light coat of matching paint after a couple of months cure. It is very permanent and you can use it on rubber ( clean area with alcohol first )
Art.

kaz442 · Answer

3m 4000 UV. It's an adhesive and sealant that is not affected by UV. It's designed for the marine industry for bedding cleats and such as well as a sealant.

mrwizard · Answer

i've been using 3m Marine poly, on various RV's for about 10yrs, ever since i quit using silicone

scott_m · Answer

Great, thanks for the responses.  Good to know that the black is UV protected.  I was going to order black or gray anyway to match the trim on the fifth wheel.  I was cleaning the butyl tape off the old flanges and fiberglass with lacquer thinner and denatured alcohol. Thanks again!

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Urethane Adheisive Caulk

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