Attic venting/insulation and drywall issues

Old 07-13-03, 01:42 PM
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Attic venting/insulation and drywall issues

First my house was built in 1936. It's a walk-up attic and it has blown in insulation on the floor and fiberglass paper backing in the eves.

We are wanting to finish the attic and gain some more living space. My question is should I take the fiberglass insulation down before drywalling the eves? As it is there is no space between the underside of the decking and the insulation. I know there should be some space there for air flow.

Opinions here or there on powered vents, I have one and I have vented soffit. I personally think the fiberglass insulation should come off. So I can get some air flow between the drywall and the roof deck.

What do the experts think?
Old 07-15-03, 01:59 PM
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I would recommend removing the old insulation, installing styrofoam baffles up against the roof deck and then re-install the old insulation if it is not damaged, wet or degraded. You are correct that if the insulation obstructs air flow between your soffits and ridge or gable vents, you do not have adequate free venting.

Forced attic ventilation is usually recommended in situations like yours because of the proximity of the roof and the room below it. Attic fans are measured in Cubic Feet per Minute (cfm). Attic vents are also rated in cfm. What this basically means if that you should not get an attic fan with a higher cfm rating than your vents. In other words if your vents will only allow 2,000 cfm, the attic fan should not be greater than 2,000 cfm. For example, if the fan was rated at 3,000 cfm and the vents were rated at 2,000 cfm, the fan would more than likely burn out after a short period of time.

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