Blown Attic Insulation Vapor Barrier

That s because cellulose is the only insulation that actually manages moisture.

Blown attic insulation vapor barrier.

Cima does not recommend the use of vapor barriers with cellulose insulation except in circumstances of exceptionally high moisture levels such as an indoor pool facility or very cold climates. To install blown in insulation in existing walls holes are drilled at the top of each stud space usually on the exterior and material is blown in via a long flexible hose. A vapor retarder is a material used to prevent water vapor from diffusing into the wall ceiling or floor during the cold winter. On the other hand an air barrier a properly detailed air tight drywall ceiling for example in the absence of a vapor barrier can be effective since it stops the flow of vapor laden air.

A vapor barrier basically helps to prevent moisture from entering your home through the ceiling floor or the walls. Attic insulation should always be installed with the paper backing facing toward the living space the ceiling in this case. Adding a second vapor barrier could cause condensation to become trapped in the insulation between the two vapor barriers. Not every wall does.

But in some cases water vapor builds up in tight houses until it forces its way through the inside wall surface the vapor barrier and insulation hitting the back of the cool sheathing then. This acts as a barrier to keep heated moist air from rising up into the attic during cold weather. The best approach for a vented attic in a cold climate is installing a layer of drywall with a good coat of latex paint the paint creates a semi permeable vapor barrier. The hole is then.

Foam blocks airflow needs no vapor barrier and has a higher r value per inch than loose fill or batts so you ll get more protection with less depth. Moisture moves by two transport mechanism. 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. With spray foam unlike with loose fill or batts you must cover the soffit vents they aren t needed to keep the roof cool.

Air movement and diffusion. The insulation fiberglass or cellulose is then placed on top of the drywall with no vapor barrier above or below. 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.