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Attic insulation-should I insulate floor to ceiling? Answered

I am in Conn. and the person helping me has said the roof needs to breath. This is a 4th story on a 3 family house. It is A shaped. I plan on covering the insulation after to finish the space off for storage. I think this will keep the 3rd floor warmer. The floor is insulated, but I wanted to do the wall which makeup the pitch of the roof. I have never heard of the roof needing to breathe before. Is this true or can I go ahead and insulate everything?


In general your roof space isn't heated, (unless your inhabiting it or just have money to burn), this accepted then you need to avoid condensation and freezing - Normally you insulate the floor of the roof space to keep the heat in the bed rooms and allow good air circulation to keep condensation down,

The water tank - if in the roof space - needs insulating to prevent freezing. leave the floor insulation off under the tank.

In the normal way families make a lot of water vapor, from cooking, washing, breathing, sweating etc. Due to the stack effect your warm air rises through the house along with the water vapor and your heat and water vapor pass through the ceilings into the roof.

You can have a dry roof by, blocking all the holes and painting the ceilings with latex or gloss paint.

You can insulate with unfaced (no paper backing) fiberglass batts. This will allow any water vapor to escape. Or you could spray foam and fill the cavity between the rafters as is becoming common practice.

Yes, roofs need to breathe - you can trap damp air against the wood, and create a great environment for mould growth and rot.

+1 (again) ;)

You want plenty of insulation laying on the ceiling to keep the heat in the house, the rest of the attic doesn't need heat/sealing. You can/should get products that leave an air-gap between the tight edge of where the roof meets the wall -- allows a little flow while maintaining good insulation around the living area.