Foam an Attic: Under Roof or Floor
Krico
| Posted in Energy, Heating & Insulation on
I have an unfinished trussed attic. We are thinking of foaming the attic. I can either have the attic floor done (about 1066 SF including a foaming an attic skylight) or the underside of the roof (about 1104SF). The installer says that if I go with the underside of the roof, I need to extend the A/C up there to prevent condensation. The only reason that I am considering the underside of the roof is that later we want to do an addition and may be running ductwork up there. Currently, there is only one duct going through the attic.
My question is if I go with the underside of the roof option, can I just cut put an outlet on the duct that is up there and cut a hole into the 2nd floor ceiling for a return?
Thanks
– Kevin
Replies
Again, no info in the profile.
Click on your name in fill in the info.
Adding direct heat or cooling to attic sounds suspicious but your question is unanswerable with no location info.
I also looked first to see what part of the country you are in before trying to answer this. Seems like in five years of being here, you could have gotten around to filling in your profile.
I am failing to understand why the installer said you would need to AC the attic. If you insulate at the roof plane, the attic is considered conditioned space. It would be warmer than the rest of the house in summer, but I can't see why it would need to be fully supplied.
Welcome to the
Taunton University of Knowledge FHB Campus at Breaktime.
where ...
Excellence is its own reward!
Ok, profile has been updated. I am in Baltimore, MD.
Ours is at the roof deck. I did not extend the ac, I have yet to see any condensation.
OK, that is probably not extreme enough either way to make too much difference.
Pros for spraying the roof plane are:
- enclose and control the entire interior space simplifying that later duct run and probably keeping some wiring cleaner for any later work. ( I would still seal penetrations like where the Romex comes up thru the top plates, etc.)
- The trusses are kept in the conditioned space which may reduce odds of truss uplift
Cons for spraying that roof plane:
>Some shingle manufacturers do not warrant their shingles when on a 'hot roof' ( I don't get too concerned over that one myself.)
>Greater surface area means higher insulation cost
There are probably more both ways.
Welcome to the
Taunton University of Knowledge FHB Campus at Breaktime.
where ...
Excellence is its own reward!
Yeah I hear you on the higher installation cost. But, because I am later planning to run some mechanicals up there, I think that it is the best choice. So, I am going to go with the consensus and not extend AC up there. Thanks for everyone's input.