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-   -   Will I have a moisture problem? (http://www.diychatroom.com/f9/will-i-have-moisture-problem-15855/)

jdsalr 01-20-2008 01:26 AM

Will I have a moisture problem?
 
Hi pros,

This is my first question here, but by reading a lot of similar posts, I am pretty confident you can help :yes:


I am remodeling an old farmhouse. The original part of the house has an attic over it, but there is an addition that does not. This addition is fastened to the side of the old house, with no ridge, and has a very low pitch. So low, that shingles are not an option...

Upon tearing down the old sheetrock from the ceiling from the 2x8 rafters, I realised there is no insulation there. It was just sheet rock, the rafters, and then the roof. Living in PA, with very cold winters, I naturally would like to insulate this ceiling. I have read a lot of horror stories about moisture build-up, and am now scared of what I should do. There is currently no ventilation for this roof either.

What are my options?

tinner666 01-20-2008 09:10 PM

As far as insulation goes, install baffles and 6" of insulation.

Should be vents in the soffits equal to venting in the ridge. That's the 'short' answer. Full lenght ridge vent and full lenght soffit vent.

jdsalr 01-20-2008 10:26 PM

Thanks for the response, but as I stated in my question....I have no ridge. The peak of the roof is actually fastened to the wall of the original house. It would be similar to what you would see on a porch roof...only longer. The span is about 17 feet.

I was told baffles would be useless as there wont be an escape for any air that the vents and baffles would supply, thus building up moisture...

My thought is that it would be better to make this 'air tight' with no vents or baffles, and use 6" insulation with a vapor barrior.

Thoughts?

the roofing god 01-21-2008 01:04 AM

you`ll never have the proper amount of insulation space with 2x8`s,you should attach same length 2x12`s,Install r-38 fiberglass rolls from underneath with the vaporbarrier towards the living space,this will allow a space for ventilation thru the rafter space for ventilation,sheath over w/ 1/2"- 3/4" plywood,if you have soffit area,cut vents in there(2" continuous thru center of soffit board),then get D.C.I. Smart Vent which can be placed a few courses before the wall to act as exhaust venting-this will need to have a 2" slot cut across the decking,from there follow the smart vent instructions for a proper install

jdsalr 01-21-2008 12:26 PM

Quote:

Originally Posted by the roofing god (Post 90503)
you`ll never have the proper amount of insulation space with 2x8`s,you should attach same length 2x12`s,Install r-38 fiberglass rolls from underneath with the vaporbarrier towards the living space,this will allow a space for ventilation thru the rafter space for ventilation,sheath over w/ 1/2"- 3/4" plywood,if you have soffit area,cut vents in there(2" continuous thru center of soffit board),then get D.C.I. Smart Vent which can be placed a few courses before the wall to act as exhaust venting-this will need to have a 2" slot cut across the decking,from there follow the smart vent instructions for a proper install

hi trg.

thanks for the advice. this makes a lot of sense. i am going to check out the smart vent and see what that is all about :thumbup:

jdsalr 01-21-2008 07:34 PM

I have been reading a lot about spray foam. could this be an alernative to not venting at all?


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