AskCodeMan

We leave in climate zone 7 and require a R-49 insulation in the roof. We exclusively see this R-value achieved by using spray foam insulation. We also see an abundance of recessed cans. We required the cans to be IC rated. My question is does this IC, insulation contact, rating also apply to spray foam insulation? Should there be any concern with the cans being in contact with the spray foam. Does the insulation have to be rated in order to be in contact with the can? Thanks.
Carlos

Carlos,

First, a question to clarify the installation: Typically, the spray foam insulation is applied to the underside of the roof sheathing instead of to the upperside of the ceiling - is the spray foam applied to the underside of the roof sheathing or to the upperside of the ceiling?

Underside of the roof sheathing. Our roof insulation requirement is R-49 and we see a lot of cathedral ceilings which results in the cans being in contact with the insulation. We have realized and accept the loss of R-value in these areas since we are typically getting only about 4-5" of foam behind the cans but our concern is the insulation being in contact with the cans. The cans are IC rated so they can be in contact with the insulation but does it go both ways especially with spray foam insulation? Thanks.

Carlos,

Okay, got it now (I wanted to make sure that is what the installation question was).

mtCDCcb wrote:Underside of the roof sheathing. Our roof insulation requirement is R-49 and we see a lot of cathedral ceilings which results in the cans being in contact with the insulation. We have realized and accept the loss of R-value in these areas since we are typically getting only about 4-5" of foam behind the cans ...

I would reconsider accepting those quite large "holes" through the insulation for two reasons:
- 1) That is a lot of R-value loss.
- 2) See reply below the next section.

... but our concern is the insulation being in contact with the cans. The cans are IC rated so they can be in contact with the insulation but does it go both ways especially with spray foam insulation?

Yes, that is a consideration to be concerned about, and address it will also address the loss of R-value too.

Here is a link to a slide show which specifically addresses your question - it was done with research cooperation between NEMA and the Spray Polyurethane Foam Alliance (SPFA):
- http://www.sprayfoam.org/files/docs/201 ... xtures.pdf

From that link:
"CURRENT DESIGNS
- Current luminaires are designed to continuously operate with external surface temperatures at or below 90°C.

- While 90°C service temperatures will not ignite foam, these temperatures are above the 82°C (180°F) prolonged maximum service temperatures of SPF."

... and ...

"CURRENT DESIGNS
- Two other concerns with current luminaire designs:
- - (1) Need full access to junction boxes; SPF coverage can prevent access in some designs
- - (2) Luminaires not evaluated for intrusion of foam; vent holes and other penetrations in current designs allow foam inside fixture"