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maximusek 12-01-2012 08:36 AM

Insulating attic with HVAC
I live in a range home with low pitch roof. In the attic I installed whole duct work, before it was in the concrete slab. Unfortunatelly my roof doesn't have a ridge vent, only two "windows" on the opposite walls of the attic. What I'm trying to figure out is this: if I'm going to make a ridge vent it will deal with the moisture in the summer but in the winter my HVAC duct will be also "ventilated". If I'm going to insulate rafters, of course moisture in the attic is gonna be a problem. Ridge vent will take care of the rafters and sheeting but not the whole room. I may have problem with mold. What should I do? I thought about insulating rafters to keep duct work "warm" and prevent form loosing heat in the winter. At the same time make a ridge vent to keep air flow between rafters plus install two fans to help get rid of the moisture in the summer. Thank you for any help.

joecaption 12-01-2012 08:47 AM

Got a picture?
Insulate the duct work not the rafters.
Is this a finished attic?
Do you have soffit vents?
Reason I ask is you should be insulating the joist not the rafters unless you plan on conditioning the whole attic.

If you go with a ridge vent you no long need the other roof vents or the gable vents. If you leave them in place the ridge will do no good.

maximusek 12-01-2012 09:09 AM

Hi joecaption,
Thank you for such quick answer, here are the answers:
-duct work is insulated (according to an inspector - they did good job)
-attic is unfinished
-making roof(new shingles) I plan to do siding and suffit vents, I understand why ridge vent doesn't work without suffit vents:)
-joist are insullated
The whole post is about: how much heat I loose from my duct work in the winter time and if I insulate attic to keep that heat inside what is going to happen in the summer, mold? It's a little tricky that is why I'm asking smarter people like yourself. I know hot air goes up and I'm trying to improve but I don't want to do something that is not gonna work and spend money for nothing.
I apologize for luck of pictures:(

Windows on Wash 12-03-2012 08:24 AM

If the HVAC installers did a good job, you should be fine.

Can about 99% of the duct work that we see be more air tight and better insulated, yes.

Hopefully they sealed all the seams and did a good job at the connections.

maximusek 12-09-2012 08:23 PM


Originally Posted by joecaption (Post 1064178)
Got a picture?

If you go with a ridge vent you no long need the other roof vents or the gable vents. If you leave them in place the ridge will do no good.

Thanks for that, I did a little research and now I have gotten what you mean. I'll do ridge vent and close up those windows so air flow is not going to take "shortcuts".:thumbsup:

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