rigid foam board insulation over rafters??


Old 04-27-05, 03:46 PM
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rigid foam board insulation over rafters??

I want to install insulation (and paneling) to my attic ceiling. My house is old and I only have 2x4's for rafters. The sheathing is built up a little but I am concerned about my roof ventilation.

1. am I being overly concerned (I live in a mild climate)

2. can I use rigid foam board over my rafters and thus having a roomy 4-5" of ventilation space.

I guess I would lose a little room that way, but I don't want to cause any damage.
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Old 04-28-05, 08:39 AM
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you can.
In an attic especially because there are no wires in the ceiling. If there were wires, the foam boards (I assume with that foil lining) can conduct electricity.
Old 04-29-05, 04:53 PM
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A couple of things to consider when you cover the bottom side of the

rafters is, if your roof has ''can'' vents, you would need one between every

single rafter. The proper correction for that would be to eliminate the ''can''

vents and install a ridge vent across the entire ridge above this project.

Another thing to consider is building codes require that foam insulation

be covered with 1/2'' drywall. Paneling does not meet the fire specs.

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