I’m planning roofing for a nearly flat (1″ in 12′ slope) roof of a sunroom here in north Florida. The roof (16′ x 15′) is 3/4″ 1×6 southern yellow pine t & g fastened over 2×6 and 2×8 cedar beams. The underside of the 1×6 is the ceiling. Eventually the roof will have a 14′ diameter dome to shed water. In the meantime I need to make it water tight. I’m thinking of self adhesive roofing systems which seem to be good for this type of roof. The first layer would be a self adhesive underlayment and because I can’t nail roofing over the underlayment since the roof is only 3/4″ thick I need a self adhesive cap sheet to finish. Grace produces an underlayment called Ice and Water Shield which seems to be an excellent self adhesive underlayment but they don’t manufacture a self adhesive cap sheet. GAF produces both but their underlayment is difficult to get and seems to be less dependable than Grace’s underlayment.
When I spoke to a Grace rep, he recommended their Grace Basik (which is a self adhesive underlayment also) as a cap sheet (it’s granulated on the top surface). He said that the GAF Liberty self adhesive cap sheet would work over Grace’s Ice and Water Shield also. I’m not totally convinced that the Grace Basik is going to be durable enough to last but the GAF cap sheet seems like it might work. GAF reps say the cap sheet will work over an underlayment as long as the underlayment is smooth and not granulated.
Does anybody have experience in this area? This is giving me a lot of angst trying to decide what the best course is and what the best combination is. Should I just add plywood sheathing over the top of the 1×6 and use nail on roll roofing? I’d appreciate all comments and suggestions.
Richard
Replies
Take a look at Polyglass. It's a two-layer, self-adhesive system. The base layer is like Ice & Water barrier. The top layer is granulated and comes in a few different colors.
Al Mollitor, Sharon MA
http://moosehilljournal.blogspot.com/
Thanks for the tip. The Polyglass is not easy to get here. Do you know if the Grace Ice and Water Shield is a compatible underlayment for the GAF Liberty top cap sheet? Seems Home Depot here sells the cap sheet from GAF but not the base sheet (although GAF says their cap sheet is to be used with the base sheet), and it does sell the W.R. Grace Ice and Water Shield. If they can be used together, I'm home free.
Richard
you are worrying too much about this.
I uise Grace for underlayment and Polyglass for overlay because that is what is available.
Also - they make 3/4" roofing nails FYI.
But - generally when there is a sheathing of boards instead of sheets of ply, there is a propensity for movement of the wood to stress the grace and overlay because of it being stuck tight to the moving wood. When it ages and gets brittle, it will crack where the wod joints are. So the standard way of dealing with that is to use a nailed down base sheet that acts asa slip sheeet to allow some movement.
But for all the close nailing needed to hold it down, you would need a thicker wood anyway or use 3/4" nails or staple through tin tabs... Lots of ways to skin the cat, but since this is temporary, just use the Grace and then whatever is available.
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One thing no one has ever accused me of is not worrying enough. I'm a great advocator of overkill. Thanks for the insight. You did make me feel a bit more relaxed. It's not rocket science. I'll take your advice.
I've used the GAF two layer peel and stick stuff. Things to watch out for:
1. The peel away layer can rip, so you may have to fold the sheet back and get a new start on it from time to time. It seems to like to tear on a diagonal.
2. Wind is a bigger PIA than ever. The peel away stuff is very light, so you have to wad and roll it up as you go so as not to make a mess all over the neighborhood.
-- J.S.
I've done Grace ice and water shield twice, working alone. Huge hassle and I strongly recommend you get help rolling it out and that you do it in the shade on a cool day.
With practice and technique, it can get easier, but it is good to warn to plan how to unroll and remove backing without geting all wrapped up in your work.;)
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
The Taunton book on roofing has a couple of tips for doing it by yourself, and they work OK, but just. What amazed me is how the slightest bit of direct sun light turns the membrane into a vicious, black, sticky mess.
BTW, thanks for the tip this summer on finishing a shed roof. You recommended "half" cap shingles. Looks good.
I've heard about how messy it can get. It could get to be a problem where I have to tie into the existing roof (6-12 pitch). How many rows of shingles do you recommend removing to do the tie in? I've just been offered a really good deal on TAMKO ice and water shield. Only problem is that this underlayment is gritty on the the upper surface, so I would have to use roll roofing over it, as the GAF or Polyglass cap sheet needs a smooth surface to adhere to. What opinions do you fellas have on the TAMKO/roll roofing combo?
Hey, I thought I was the Oldtimer. I'm an extremely amateur roofer. Better ask one of the pros on BT!