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Community and Q&A

Confused about insulating a kneewall attic space

TIMGABE | Posted in Energy Efficiency and Durability on

I am confused with all the different options concerned with insulating a kneewall attic space in my Cape Cod home. Presently, there is insulation on kneewalls (fiberglass R-13). There is no insulation on roof deck boards or baffles. There are soffit vents and a ridge vent.

The room is extremely hot in summer and cold in winter. What are the best options aside from spray foam to make this area of my home more comfortable and energy efficient?

What about the following:

1. Blocking under knee wall to stop air infiltration under floor and downstairs ceiling?

2. Is it allowed for some type of board (plywood, foam board, OSB) on the backside of the knee wall to stop air infiltration into living area? Is there a concern with moisture and mold?

3. If I put baffles on roof deck then insulation over baffles would that maintain more tolerable temps in this area? Is there concern with damage to roof deck with regards to moisture or heat in summer?

4. What to do for attic ceiling?

Thank you Tim

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  1. GBA Editor
    Martin Holladay | | #1

    Here is a link to an article that answers your questions: Two ways to insulate attic kneewalls.

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