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JasonCA 10-04-2010 11:27 PM

Attic Foam Board Insulation
2 Attachment(s)
Hi Everyone,

In the attached picture, you can see area D. I already have insulation on the floor of the attic (area's B and A). However, I don't have any insulation in the D area.

I was thinking about adding Celenit for Insulation of flat and sloping roofs INSIDE the attic. I'm not sure about what the pro's and con's would be. I'm not sure what other materials I could use or what would exactly be proper for insulating the attic inside the slopping roof.

Alternatively, it seems like I could just pick up some Rmax 1" x 8' x 4' R-5.9 Insulated Sheathing and put it in-between the beams in area D of the attached picture. It seems light enough to cut and bring into the attic. However, i suppose it's foam, and so I am not sure about the safety of it?

I've attached a picture of the Rmax panels.

I am wondering about the safety of this? Or what is that I should consider when insulating the roof of the attic?

FYI, I live in California. My goal is to keep more heat out of the attic since I use it for storage. And to keep the attic cooler to avoid the house in general from getting hot when the sun is blazing outside.



Gary in WA 10-05-2010 11:51 PM

Check with your local B.D. for covering the foam.

Five Counties in CA would be better adding insulation above the ceiling than a radiant barrier:

Check your location and R-value there now:


rodeo 10-06-2010 03:35 AM

looks like you are making an unvented attic with its space conditioned like the rest of the house.
this is often done by sprayfoaming between the rafters or even dense pack cellulose. the website talks about this method.
another way to leave the rafter bays empty and attach foamboard to the underside. in this scenario, you could also turn the empty rafter bays into
a vented one by adding soffit and ridge vents. youll need to cover the foam with sheetrock. that will add some weight so check the rafter size. its kind of hit or miss with building codes. some jurisdictions support \unvented attics and some dont.

federer 10-07-2010 12:56 AM

for my roof i think i am going unvented. apparently its the 'new' thing to do

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