Low slope wth gaf adhesives

Hi everyone. I have a small low slope roof over my shed. Just shy of 100sq ft. Re. Gaf adhesive products, I was advised at a big box store to use storm watch as an underlayment and liberty cap sheet over that? I’ve been tooling around the internet and am now questioning if I should have just used felt and then the cap sheet? I already put down weatherwatch over half the roof space. The question arose in my mind because of the granular nature of the weathwatxh and my wondering if the cap sheet will stick to that in the long term. 2nd question, if the weathwrwatch can be used underneath, it appears the lap edge has a peelable strip coving the adhesive on top??? Or is it just a self sealing edge for nailing down? Thank you very much in advance.

I think I answered my second question with a piece of scrap. Appears to just be a self sealing edge.

No don’t use weatherwatch under gaf liberty. I hate when people get advise from big box stores for this exact reason! You are correct in that it will not properly stick to the sandy surface long term. What you want is gaf liberty “base sheet” under the cap sheet. If that is not available I do find it acceptable to use the “grace” brand ice and water shield as it has the proper surface for the cap sheet to stick to. Also don’t use regular felt (its not strong enough over time).


Figures. I’ll just lay it out there now - Home Depot. Thanks for the CORRECT advice. At least I only wasted 50bucks and an hour or so. Hopefully I can pull it up easily… probably not.

You defently want to use use the right base sheet. When you go to install the cap sheet lay it out exactly where you want it. Leave a little extra over the edges, then while holding it in place or you can track the top salvage edge in a few spots, then peel one half of the release film at a time without moving the cap sheet. If it’s your first time working with self adhesive, it sticks pretty much immediately in contact. It’s easy to work with just make sure it is where it needs to be when you pull the film out.

If you already installed the weather watch then at this stage its best to just leave it there and get the “nailable base sheet” and go over the weather watch with it. I’ll try to find a video for you later.

this is a great video to learn from. However in your case I would just use the nailable base sheet over the already installed weather watch and then the cap sheet on top of that (you can ship the seal adheared base sheet part). Also don’t go to home depot and ask for what you are seing in this video, 90% chance they will give you the wrong stuff.