I am in the process of finishing my bonus room (attic space above the garage). There are soffit vents and a ridge vent. If I put insulation in between the rafters before I drywall the ceiling, will that adversely affect the ventilation? I am also replacing the soffit in that area. Do I still need the soffit vents with the insulation in place? Thanks, Jim

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    You have a decision to make. Do you want to convert to a "hot roof" (unvented) and assume risk of premature roof failure and reduced energy efficiency? You've told us nothing about your climate, home style, HVAC system, etc., so it's difficult to provide advice.
    – isherwood
    Commented Nov 26, 2018 at 18:08

1 Answer 1


In climates where you’re heating more than cooling during the year, yes, it’s advisable to add attic insulation, but: 1) you must maintain CONTINUOUS ventilation, and 2) you must maintain a minimum of 1” air space between the insulation and the roof structure.

1) You want “cross ventilation”. Your soffit vents and ridge vents are doing that now. Just make sure EACH JOIST SPACE has a soffit vent AND a ridge vent after you install the attic insulation between the joists.

2) Make sure there is a minimum of 1” air space between the insulation and the roof structure, especially at the soffit vents. Insulation tends to “fall down” and block the soffit vents, so they often use cardboard baffles to maintain a clear vented opening.

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