Do I Need Attic Vapor Barrier In Sc

Avoid adding interior vapor barriers where the outer wall construction already includes a material with vapor barrier properties.

Do i need attic vapor barrier in sc.

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. The theory is that part of the moisture vapor in the house is actually blocked by the drywall and paint on the. Seal the air leakage pathways. You have loose fill insulation in the attic which doesn t have a vapor barrier.

If you are not sure if you need insulation in your walls follow along with this flow chart. While you are inspecting the attic check to see if there is a vapor barrier under the attic insulation. 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 vapor barrier detail for cold climates.

Even though we apply vapor barriers to exterior insulated walls in cold climates it s no longer recommended for ceilings floor of the attic. No you don t need a vapor retarder class i or otherwise. The paper facing contains a layer of impermeable asphalt that prevents water vapor from passing through it. If there does not appear to be a vapor barrier you might consider painting the interior ceilings with vapor barrier paint.

Most authorities recommend vapor barriers in certain situations. In areas with high humidity such as greenhouses rooms with spas or swimming pools and bathrooms vapor barriers are often recommended. After the insulation is in place you will want to add a vapor retarder sometimes called a vapor barrier if you need one. A plastic vapor barrier is best installed in a vented attic within climates with over 8 000 heating degree days.

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. Not every wall does. Because it s nearly impossible to seal penetrations in the ceiling the reality is water vapor will get into 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.