ridgid foam under rooled roofing
gbwood
| Posted in Energy, Heating & Insulation on
howdy folks-
I have been hiding in the shadows around here for a bit, havn’t posted much lately, but I got a real basic question on roofing- my brother & I put a 13′ X 20′ addition on my dad’s place-actually it’s a separate structure, anyway, pops is a retired engineer, he designed the roof / ceiling to be 2 X 6 rafters sitting on a 6 X 12 ridge beam with 2 X 6 T&G as the sheeting (if that’s what you would call it.) It slopes about 8″ in 10 feet. He wants to use foam insulation under the rolled roofing, so my question is, whats the best way to do this, or is there a better way?
this is in San Deigo, by the way…
Thanks a bunch,
greg
edited to add, I ment rolled roofing…
Edited 9/22/2007 5:27 pm by gbwood
Replies
Your father's design is your basic, time honored, built-up roofing.
There are many thicknesses of insulation board available, but he should use one that's designed for roofing applications. Sidewall foam is a bit soft to use under foot. You can find this insulation at just about any roofing supplier. It is best to screw this down with screws and plates.
As to "rolled roofing". What's called 90 lb. granulated rolled roofing is cheap to buy, but it's not worth two cents. The best DIY membrane I could recommend is known as "Peel and Seal". That is a brand name, but generically it is an adhesive backed SBS (modified asphalt) membrane.
This SBS membrane is available in a variety of colors, just follow the mfrs. directions.
John Svenson, builder, remodeler, NE Ohio
Rooled roofing is definitely not worth a hoot, other than for a chicken ccoop. The peel/stick kind you mentioned is definitely better, but might not stick well to foam, depending...Neither is a BUR roof though. That takes a kettle and hot asphalt and a pro to install.For DIYs I would place the faom, then screw plywood down through the foam, then the roofing over that.
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I'd be a little concerned whether the 2x6 rafters are strong enough to hold up what I interpret to be a 2" car siding roof.
Re foam under the rolled roofing, the concern would be whether the roofing can be fastened down securely without seriously denting the foam. I suppose it could be glued down somehow, but I don't know how. And at that slope rolled roofing is a little iffy -- might be better (though certainly more expensive) to go with rubber.
For something that size, 2x6 is standard fare in CA
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