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-   -   Insulation on top of old roof deck??? (http://www.diychatroom.com/f2/insulation-top-old-roof-deck-34711/)

ubie42 12-30-2008 02:22 PM

Insulation on top of old roof deck???
 
I recently had a new pitch roof built over our previously flat roof. The old shingles were torn off, leaving just the deck, and the new roof built over top, leaving new attic space. I do not have adequate insulation under the old deck so I want to add insulation.

I would like to do it my self, but I am leary of blown in insulation. Everything I read seems to suggest having a professional install it. If went with rolled insulation can I just roll it right on top of the deck?

Thanks,

joed 12-30-2008 03:11 PM

I don't see why can't just add it on top of the old deck.

Wildie 01-01-2009 01:23 PM

I had a house with a floor in the attic. The joist bays were filled with rock wool insulation! I installed fibreglass bats by laying them on top of the wooden floor! I never encountered a problem with this and I was quite happy with the reduction in the fuel bills! Your situation is similar to this, and I would expect that insulation on top of the old roof deck would be effective!

Tom Struble 01-01-2009 01:51 PM

unfaced insulation?

Wildie 01-01-2009 01:55 PM

Quote:

Originally Posted by strublesiding@optonline.n (Post 205308)
unfaced insulation?

Yes! 2X4 R20 bats!

ubie42 01-05-2009 06:31 PM

Thanks! I measure the current insulation and have what I believe is fiberglass...about 3.5 to 4 iches. Including the the old roof deck, what R value would you say I have? I would like to get it up to at least R-39, and if I can save a couple hundred bucks by selecting a lower R-value, I'll do it. I am little tight on cash... Also, how much is enough? Is there really going to be much of a savings once you get to R-39 and above. Do I need R-60 if R-40 is good enough?

Wildie 01-05-2009 07:22 PM

Quote:

Originally Posted by ubie42 (Post 207549)
Thanks! I measure the current insulation and have what I believe is fiberglass...about 3.5 to 4 iches. Including the the old roof deck, what R value would you say I have? I would like to get it up to at least R-39, and if I can save a couple hundred bucks by selecting a lower R-value, I'll do it. I am little tight on cash... Also, how much is enough? Is there really going to be much of a savings once you get to R-39 and above. Do I need R-60 if R-40 is good enough?

I would start with R20 then if you think that you would like more in a few years, put in another layer! Theres no limit, beyond space, to how many layers you can have!


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