Friday, September 16, 2011

We are in the pink!

For a while, we have been debating on how to ventilate the roof space.  I hemmed and hawed over types of insulation, whether the roof was going to get the ventilation it "needed," and how I was going to make this all work.

I realized early on in the process of thinking about insulation for the roof-rafters, I would need to provide adequate air-flow to allow the whole "unit" (insulation, roof, and ultimately the house) to breathe.

We are in the pink, so to speak.  R-30 on top of the ceiling, and below the roof rafters.
We will have a plastic (4mil sheet) "vapor barrier" installed on the ceiling rails, and the drywall placed on top of it.  We have not worked out the insulation strategy for the walls yet, however.

Our research tells us that our house, a two-wythe brick (with an air-gap between the wythes) load-baring house should really not be insulated, and if the walls are insulated, there be sufficient air space to allow the walls to breathe.  A typical fiberglass insulation with a vapor barrier is not the recommended way to go...

"Clearly, fiberglass batts should never be used to insulate the interior of a brick wall. (Since fiberglass batts are permeable to vapor and air, they permit interior moisture to condense on the cold bricks. That's bad.)" POSTED ON AUG 12, 2011 BY MARTIN HOLLADAY, GBA ADVISOR

So our thought process is leaning toward rock-wool (also known as stone-wool or mineral-wool), and no vapor barrier. Spray foam (closed cell) is the other choice, but we were not interested in coating the brick for a variety of reasons--With the exception of low-toxic cementitious foams, most foamed-in-place insulations contain hazardous ingredients and are toxic during application...also, the majority of commercial foams use ozone-depleting blowing agents....The EPA's concerns are discussed here.

Stay tuned...

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