Home>Discussions>INSULATION & HVAC>Ventilation for a 2x4 trussed roof that has a finished attic
1 post / 0 new
Ventilation for a 2x4 trussed roof that has a finished attic

Hi all,

I recently purchased an old farmhouse and have been doing a major restoration on it while living in it and keeping wife/new baby happy. Tough chore, trust me.

Anyways, I need to put a new roof on and would consider adding more roof insulation at the same time. This has been a tough decision for me and I have been battling it for the last 6 months and now I need to make a decision.

The roof is trussed out with 2x4's. The current roof is shake, tar paper, and lap board deck. Under the deck is some verry old insulation (I think its called mull wool?). Basically its about 1.5 inches think and has a tar paper on each side. Then, drywall on the inner most surface. It is a finished atic type living space with knee walls. There is a narrow horizontal roof at the peak and it sits about 1.5 feet below the peak. The house has several large gables that limit the abount of horizontal facia/soffet. Have I painted a good picture thus far?

The roof is not ventilated at all. It is, however, very solid. I do not believe there are any moisture issues. This may be due to the dry climate and windy conditions here in northern Montana. But, it also gets very cold, which would lend itself condensation.

I definatley need a new roof and sometimes I think I should just strip the roof and put asphaul shingles down and be done with it. I'm not opposed to putting delta rib down either. But, I keep going back to the condensation issue and wonder if I don't have issues because very breathable shakes were on it before. What do you think?

Then, with the fear of condensation, I keep thinking about this web page:
Stuffing cellulose would be very easy and cheap. I could just pull a couple boards here and there and stuff away. But, this is the only place I have really seen this discussed. What are your thoughts on this?

I could also do a warm roof like this:
But, this would significantly add to the cost and time. But, I would rather do it right the first time. Would this be possible on a slanted roof and what thickness would you go with on foam board?

Lastly, I have contemplated doing both of the above. This would provide me with more insulation (although still short of what I should have in northern Montana). Any thoughts on this?

Any advice you can provide will be greatly appreciated as most roofing contractors that I have had by say "we can do what ever you want." Which I'm glad, but they do not provide any advice or it seem shakey at best. Thanks again and god bless.

Sponsored Stories

TV Listings

Find TV listings for This Old House and Ask This Old House in your area.