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dpb dpb is offline
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Default Celotex? Old roof underlayment

Una wrote:
Correct, no attic. It is a low angle roof over cathedral ceiling with
exposed structural members and tongue and groove planking. That room is
cold in winter and hot in summer; a well insulated roof would pay for
itself in just a few years. I guess my questions are mostly academic,
but I also wonder if stripping off the fiber board is really necessary.
I suppose it presents a technical problem if 4 inch insulation is to be
put on above deck. And I would like to be sure that new insulation
will make a significant difference.


If there was no insulation other than the celotex before, it will make a
significant difference. A quick look didn't find data in my handbook,
but I'm comfortable an inch of old celotex isn't anything remotely
approaching an inch of a modern solid-foam in effectiveness.

One disadvantage I see given what you've already stated in leaving it
there is you can't see the condition of the sheathing underneath before
you cover it back up -- you've already mentioned it's leaked before and
there is visible damage in places. I'd want to know what else is there
hidden before putting the new back on.

I'm still of the opinion sounds like your roofer is doing you well--I'd
go with him on this one from all I can tell from here (which, of course,
isn't a lot ) but I think his is the right call.

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