Which Sikaflex?

hodag,

This is going on the sidewall for a Carefree awning install, not the roof.


Thanks for the recommendations, guys.

715 semiself leveling on a TPO roof

I am re-caulking my NL with Sikaflex 505UV (white). I read a lot of forums and info about caulk/sealant and finally chose 505UV because Sikaflex says that it is made for external sealing on RVs. I did not run across any forum posts about 505UV that I recall. But, I did find that many RV supply stores stock it, including my local dealer. The other contender was 3M 4000 UV, which it seems is what the NL factory used originally. Some of the factory caulking is still good after 8 years but some had failed entirely.

The 3M product is tough and tough to remove. I won't know how the 505UV holds up for a year, or several. As near as I can tell, both the 4000 UV and 505UV use the same basic chemical base; Polyether. In a couple of areas I removed only the top part of the 3M product then applied 505UV over the top of it, figuring that they may be compatible. I'll find out after some time.

291 or 291 fast cure are the ones commonly used to bed hardware on boats.

Now for a controversial comment:

Running a thick bead around fittings does very little - in my opinion - to seal anything. You will not see this approach taken on a boat. It is the sealant under the flange of piece you are fastening that is doing the sealing. This is protected from the weather and UV by the flange, and compressed under it by the fasteners. Now I realize that I am at odds with nearly the entire RV industry which believes slathering sealant all over the outside of everything is the solution. You will never see this done on a properly built boat, which sees a lot more water, and the consequences of leaking potentially fatal.

I will note that the brackets of many awnings are very poorly designed, with fasteners bare through the skin and no flange near it to seal. In that case what else can you do but slather? They are designed to leak.

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