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djgreer1963
attic insulation and venting

I recently had my attic insulated with spray foam. The house was built in 1955. When they sprayed, they also sealed the vents on either end of the attic. I have questioned that there is no way for the hot air of summer to escape, but have not received an understandable answer. There are no windows in the attic. It seems to take a longer time to cool down the house. Was it right to seal the vents?

bp21901
Re: attic insulation and venting

Do you have soffitt vents? How about vents in the roof or the length of the peak?

keith3267
Re: attic insulation and venting

If they insulated between and over the ceiling joists (floor of the attic), they should not have sealed the vents. If they insulated between and over the rafters and the gable walls, then the vents should be sealed.

Insulating the rafters and gable ends makes this space part of the "envelope" and should have heating and cooling to the space. You can use this space, subject to all other code requirements, as living space or storage space.

If only the ceiling joists were insulated, then you need to meet the requirements for attic ventilation that any insulation would require. If the insulation does not cover the tops of the joists, and worse, if it only comes up part way, then the joist are acting like a heat sink, conducting heat in or out of your house. You are not getting the full effect of the insulation.

Re: attic insulation and venting

The most common mistake homeowners make when installing insulation is to block the flow of air at the eaves. NEVER COVER ATTIC SOFFIT VENTS WITH INSULATION — use rafter vents and soffit vents to maintain airflow!

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