Add to attic insulation?

[DaveO]

I heard a radio show some time back about adding to attic insulation to save heat and money. (I believe the word they used was cellulose, but I'm not sure.) Then the other day I was in a neighbor's attic helping him run cable, and I noticed the owner (the current occupant is a renter) had either augmented or replaced the insulation with loose white stuff.

This sounds like a good idea, but I'm sure there are details to consider. What does a DIYer need to know before starting something like this?

Thanks

[Wgoodrich]

You must maintain air flow through you attic. Some have gable vents but most have soffit vents and roof vents. The soffit vents are the air intake and the roof vents are the air exhaust to vent you attic protecting from moisture build up. This air channel must remain clear. If you have soffit vents look at the point above your outside walls to see if you have air shuts normally styrofoam channels installed to keep the insulation in the attic from blocking that air flow. If they are there and are high enough to hold back you added insulation you are fine. If you don't have this shute to protect the air flow into the attic from the soffit vents then install them in each rafter space to ensure air flow before you add insulation.

Also a vapor barrier is required to be installed on teh warm side of the attic bening against the ceiling. No added vapor barrier can be installed. A form of vapor barrier is plastic sheeting or paper backing on insulation.

The white insulation you saw is probably blown in fiberglass. This is fine and can breathe as required to allow moisture from condensation to escape through that insulation. Do not install a double vapor barrier thus trapping moisture.

The thickness of your insulation required depends on the location your house is in geographically. Insulation is rated in R value. Midwestern Indiana requires an R 30 insulation in the attic. You may require more than that or less than that depending on location.

Good Luck

Wg

[DaveO]

Thanks for your post, WG, I knew there would be more than meets the eye. I'll check out those details when I get back to the house.