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toh123
Retrofitting insulation in a gambrel roof attic

I'm adding insulation to the attic space of my home that has a gambrel-style roof. I am comfortable with insulating the attic area above the ceilings, but am uncertain of the best way to ensure that the vertical wall/ceiling areas (I believe it's called the mansard-style roof section) contain sufficient insulation without disrupting any of the ventilation air flow from the soffits. I am open to using blown-in cellulose, f/g batts, or any other type of DIY-friendly product. Any advice would be appreciated.

BuilderPete
Re: Retrofitting insulation in a gambrel roof attic

toh123,

Please supply a little more information.

Are you insulating the attic floor joists only?
Will you be converting the attic into additional living space?
What size are your attic floor joists (2x8)(2x10)?

Some helpful hints-

1.) Never compress any type of insulation. Insulation performs best with the proper amounts of air gaps (fluffy insulation good, squished insulation bad).

2.) Attics need to breath, don't restrict air flow from soffit vents, gable vents, ridge vents, or roof vents.

3.) If your installing fiberglass batting the paper side always faces the heated space (living space).

4.) don't forget to wear a dust mask, long sleeve shirt, gloves, and make sure to keep hydrated in hot places.

Hope this helps you and good luck!

Pete

_______________________
Measure once, Cut twice

toh123
Re: Retrofitting insulation in a gambrel roof attic

Hey Pete,

I'm only insulating the attic floor space which are 2x8's. It already has some blown-in cellulose, but it has since settled with time. I'll be adding to the insulation that is existing with new. But my question is about the lower section of the roof slope that is at nearly a vertical angle. In this section, the cavity in-between the roof sheething and the adjacent interior walls is probably less than ten inches so I don't know if insulation could be retrofitted without interfering with the air flow from the soffit vents. I am unsure if that area is even meant to be insulated, but this being our first winter in the new home, I am concerned about the amount of heat that would be lost there. I have never had any prior experience with roof styles that have multiple-pitch slopes such as this, so I don't completely understand how they are engineered to be properly insulated vs. a gable roof system. Any thoughts on this? Thanks.

BuilderPete
Re: Retrofitting insulation in a gambrel roof attic

toh123,

Thanks for explaining more.

It is not required to insulated any rafters (structural framework of the roof) if your not using the attic for living space. The soffit portion (eaves or overhang) should not have any insulation in these areas. However, If you decide to add insulation to extend over the lower wall (top plate). You will need to add a durovent foam attic baffle in these areas to allow for air flow. Check this site for more info: http://store.contractor-pro.com/durovent-baffle-235-x-46-50bag-1400plt-p-2801.html Your local roofing supply should have these or similar. They are fairly inexpensive and really work excellent with blown insulation.

I hope this helps, post again if your not sure.

Pete

_______________________
Measure once, Cut twice

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