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"