Do I Need Attic Vapor Barrier In Sc

Your first job after the studs are in place is to fill those walls with insulation.

Do i need attic vapor barrier in sc. The vapor barrier might be tarpaper kraft paper attached to fiberglass batts or a plastic sheet. A plastic vapor barrier is best installed in a vented attic within climates with over 8 000 heating degree days. If you are not sure if you need insulation in your walls follow along with this flow chart. Even though we apply vapor barriers to exterior insulated walls in cold climates it s no longer recommended for ceilings floor of the attic.

By the time you paint the drywall though you ve brought it into the class iii vapor retarder range between 1 and 10 perms and even less water vapor will diffuse through. The paper facing contains a layer of impermeable asphalt that prevents water vapor from passing through it. Because it s nearly impossible to seal penetrations in the ceiling the reality is water vapor will get into the attic. Do not add a vapor barrier on top of the insulation in your attic since the paper facing on the existing insulation is the vapor barrier.

Attic insulation and vapor barrier it is not necessary to have a vapor barrier for either greenfiber natural blow in or owens propink blow in insulation except if your local building codes require it. Not every wall does. No you don t need a vapor retarder class i or otherwise. Avoid adding interior vapor barriers where the outer wall construction already includes a material with vapor barrier properties.

The theory is that part of the moisture vapor in the house is actually blocked by the drywall and paint on the. If your climate does not meet these conditions a vapor retarder like latex ceiling paint will work well for your house if you are in all other climates except the hot dry and hot humid. After the insulation is in place you will want to add a vapor retarder sometimes called a vapor barrier if you need one. If there does not appear to be a vapor barrier you might consider painting the interior ceilings with vapor barrier paint.

Attic vapor barrier detail for cold climates. Seal the air leakage pathways. If your current insulation is a cellulose product similar to the greenfiber natural insulation your existing 6 is equal to about a r 19. You have loose fill insulation in the attic which doesn t have a vapor barrier.