I just added a cellulose insulation into my attic.

Yes, I added the rafter vents but I also have two mini windows that are covered with siding window covers allowing the air flow. I normally closed these 2 windows during the winter time and open during summer. I just closed them with the board of the window size to block at least some cold getting in.

My question is do I still need to close them during winter now when I have the cellulose insulation? It's raining right now and quite of humidity is getting there. And since it is insulating properly, the warm air from the house is not getting there to push the humidity out. Hopefully, the wood won't start to degrade because not warm air escaping the house removing the humid air there.

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1 Answer 1


You ideally want your attic to be the same temperature and humidity as the outdoors. By sealing, you almost certainly are making the space warmer and more humid. In hot climates, this could cause your roof to get to hot and reduce the lifespan. In cold climates, the attic could stay or get above freezing, cause melt, and refreeze at the edge causing water dams.

  • I'm in mixed climate(Ohio). So you are suggesting keep it open even though it's raining outside and the humidity penetrates inside through these "window" openings?
    – Grasper
    Oct 21, 2016 at 21:00
  • I live in Ohio as well. If rain is not actually coming in, there isn't a problem. You don't want to trap air in the attic. Modern roofing practice goes to good lengths to ensure there is sufficient airflow. Oct 24, 2016 at 11:02

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