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123ozzie 11-26-2011 11:07 AM

Roof venting around can lights
I have an addition on my house (12x15, 4 season room) that has a cathedral ceiling. I have installed can lights in a few of the rafter bays which will make installing roof baffles difficult. How important is it to vent every bay, and if I dont vent the few bays with cans in them, should I still hold the insulation off the roof sheathing by an inch? The cans are airtight IC cans. Thanks

Gary in WA 11-29-2011 07:44 PM

Every rafter bay requires venting. Where are you located?


Windows on Wash 11-29-2011 08:04 PM

+1 on venting every bay.

We just stripped a roof that was a cathedral roof with can lights (not airtight) and the rot was most concentrated in the rafter bays that became obstructed (insulation batt falling down) and had the can lights.

Can lights, regardless of airtight or not, will be a big short circuit in the insulation layer and will be points of additional moisture because of the interruption in the vapor retarder and lower than average R-Value. Even if you don't think there is air leakage, there probably is.

You need to vent each bay.

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