Insulation between top floor and flat roof- efficient + green possible?

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Topic: Insulation between top floor and flat roof- efficient + green possible?

Insulation February 26, 2013 at 11:51 am

Insulation between top floor and flat roof- efficient + green possible?

Any suggestions for efficient and effective but non-toxic and reasonably priced insulation for the area between a brownstone’s top floor and the flat roof?  I’ve been researching it and it seems there was some dialogue about cotton batt (recycled denim) a number of years ago, and then there is the question whether wet or dry cellulose is appropriate under a flat roof both in terms of risk of mold and losing its insulating properties if wet cellulose doesn’t dry properly before being sealed up, or if dry cellulose gets wet (if that is right) not to mention that it seems cellulose is much pricier than fiberglass insulation. I’d be interested to know what others have done.

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I had cellulose blown into my cock loft [the term for the space between a row house's top floor and the flat roof] about 35 years ago. I don’t think moisture is a big problem because it’s NOT sealed up. Standard practice is to install a couple of mushroom vents to vent the space, something that’s needed with any roof insulation not installed over a vapor barrier.
I’ve never inspected the space for mold but, FWIW, I was able to check whether the fire-proofing was still effective a few years ago. A handful of insulation came out when I had a vent fan installed in my top floor bathroom and I tested it by trying to ignite a pile of the material with a match; it self-extinguished after a couple of seconds, just as it’s supposed to. The fire-proofing chemical [boric acid?] is probably not all thet green, but I wouldn’t want flamable material blown into my house.

I had my cockloft insulated a few weeks ago.  Didn’t need vents since it’s not an airtight space.  The material used is chopped-up newsprint I think.  Some companies insist on vents which I thought unnecessary.  I used Brooklyn Insulation & can’t recommend them highly enough.  They were terrific – fast, tidy & reasonably priced.

Has anyone busted through and opened up the cockloft? I have about 2-3 feet that I would love to claim. 

Original poster here – after researching the matter we’re probably going with dry cellulose and found a specialty company to do it, for less than the general contractors wanted to blow in fiberglass, so that’s our game plan.

I’m a insulating contractor doing work in you area and would be happy to answer any questions you might have. You can give me a call at 6313366609 rich

Insulating a craw space is the most coast effective area in a Browstone…. Why because most Bstones are built without much room in the wall cavites. That is why you need to Insulate the deck of the upper floor to slow the heat rise. I do flate roof insulation trought the metro area and have been doing insulation since 1979. If you have any questions please e mail me or call me at 516 903 7401 or
please view my web site at


Why be cold this winter when you can save $ and save Energy.

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Their other prducts that can be used like Airkrete and non toxic blowing insulation. This is un treated and safe for you and your family.

Jeanmarine, can you share who you decided to use and your experience. Thanks in advance.

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