In regards to using ICF for roofs, products like InsulDeck still don't provide the high R-value that I am looking for. Is there any ICF for roofing that will provide a high R value?

When I go with ICF walls for my home, my only option might be a wood-framed truss roof. I know I can get R-50 in there relatively easily. 90% of the ICF homes I have seen usually go this route, ICF walls and then stick frame roof & attic.

Lbear,

It might be possible to get an R-50 on the attic floor but if you plan to insulate the roof instead, then you may need polyurethane or iso boards on top of the roof decking.  This way would be continuous and fully insulate the rafters.

Posted By Alton on 15 Jan 2012 08:16 AM
Lbear,

It might be possible to get an R-50 on the attic floor but if you plan to insulate the roof instead, then you may need polyurethane or iso boards on top of the roof decking.  This way would be continuous and fully insulate the rafters.

Do you have a link to photos of this being done?

Too bad that don't make an ICF panel that would give one at least R-40 at the roof.

Posted By Lbear on 15 Jan 2012 02:04 PM
Do you have a link to photos of this being done?

Too bad that don't make an ICF panel that would give one at least R-40 at the roof.

Yes, see http://www.pima.org/SpotLightFiles/tb114.pdf   It is called nail base and made by various companies.  Primarily two flavors:  ventilated and un-ventilated.  In your climate I would use the ventilated type at whatever thickness needed and available.

Even though Insul-Deck's site says their R values go up to 25, if you use the 10" thick form you will have over R40. I think they are just being conservative with their statements.

Posted By ChuckLohre on 15 Jan 2012 03:15 PM
Even though Insul-Deck's site says their R values go up to 25, if you use the 10" thick form you will have over R40. I think they are just being conservative with their statements.

The problem is that there are areas in the InsulDeck that are only 2" thick with EPS. That would drop that area to R-9. The thicker areas, yes, they would have R-30/40 but the areas of 2" thick EPS will drop to R-9.

But that is no different than batts between framing! Or a huge picture window in the middle of a wall!

You need to look at the overall performance.

Also, forget R-value, it's a fictitious number when talking about EPS products and concrete, it's not a fair comparison to regular Batt insulation. Look at the U-Value or K-Value...you will be surprised