Question - Which way should insulation face in attic?

Answered by: Rose Henderson  |  Category: General  |  Last Updated: 22-06-2022  |  Views: 761  |  Total Questions: 14

Hi Kim, Regardless of whether fiberglass insulation is installed in a wall, attic, or crawlspace; the paper facing should always face toward the inside of the home. That's because the paper contains a layer of asphalt adhesive which prevents water vapor from passing through it. You can use either faced or unfaced batting for this installation. When using insulation that has either paper or plastic facing, that moisture barrier faces outward, toward the attic space. Even if the attic space is unheated, it typically is warmer than the outside air in winter. In an upside down installation, where the paper faces the unheated portion of the home, moisture from the humid inside air can condense and become trapped inside of the insulation during cold winter months. This will likely result in fungal growth (mold) and rot. In order to prevent condensation from forming, a vapor barrier should be placed on the warm side of your insulation to stop warm, moist air from condensing on a cold surface inside your wall. In cold climates like Canada, for most of the year the vapor barrier should be on the inside of the insulation. Faced insulation has Kraft paper on one side to act as a vapor retarder and help prevent moisture from entering the wall cavity. Unfaced insulation is insulation only, for use when a vapor retarder isn't needed.

https://www.energiaus.com/news/2016/8/9/is-air-sealing-your-attic-worth-it

Air sealing your attic is essential to an energy efficient home. Air sealing your attic and having it appropriately insulated helps minimize the stack effect. This will make your home's temperature more comfortable and easy to regulate, while protecting you against high energy costs year-round.

https://www.insulatekansascity.com/insulation-blog/9-signs-your-home-is-under-insulated/

Do the touch test. The interior ceilings, walls and floors in your home should feel warm and dry. When drywall and paneling inside a home feels damp or cold, there is not enough insulation. Alternatively, when touching an exterior wall, it should feel cold because insulation is keeping warm air inside a home.

https://www.energystar.gov/campaign/seal_insulate/do_it_yourself_guide/adding_attic_insulation

The recommended level for most attics is to insulate to R-38 or about 10 to 14 inches, depending on insulation type.

https://heightslibrary.org/materials/hrrc/31-Insulation_Techniques/INSULATING_AN_ATTIC_FLOOR.pdf

If you insulate the attic floor, it is also important to have a vapor barrier in place, to prevent warm, moist air from rising into the chilled attic from the living space below. The moisture will condense on the wood and insulation, reducing the insulation R-value and encouraging the growth of mold and mildew.

https://www.architectmagazine.com/technology/understanding-vapor-barriers_o

The original reason for using vapor barriers was a good one: to prevent wall and ceiling assemblies from getting wet. This can lead to significant moisture problems and mold; problems occur when walls get wet during construction or more often throughout the home's life.

https://www.metrohomeinsulate.com/blog/too-much-insulation

But there may be a theoretical point of “too much. ” If a home is over-insulated and is too tightly sealed, moisture can get trapped inside. Without proper ventilation, a home can build up too much moisture, especially in the attic (warm air rises), which can cause mold problems and, overall, lower indoor air quality.

https://www.timesunion.com/living/article/Roof-rafters-shouldn-t-be-insulated-1077650.php

Insulating between rafters will do no good, because the attic should be ventilated, and the rafter insulation would be between two unheated spaces. You can add insulation to the floor; the more the merrier. Also, make sure the attic is well ventilated. Cold roofs prevent ice dams.

https://www.doityourself.com/stry/do-i-need-to-remove-old-insulation-before-adding-new-attic-insulat

Do I Need to Remove Old Insulation Before Adding New Attic Insulation? Your current attic insulation will form the basis of the additional attic insulation that you are planning to install. Therefore, unless it is damaged or your roof is damaged, you should not have to remove the original insulation.

https://www.garagejournal.com/forum/showthread.php?t=229283

Back years ago, it was always said to NOT put a plastic vapor barrier over the insulation before hanging drywall or whatever material you decide to hang, as it would cause the room or building to act like a greenhouse.

https://www.certainteed.com/insulation/fiberglass-insulation-and-vapor-barriers/

Vapor barriers applied over the face of the insulation provide additional benefits in the fight against moisture. Usually composed of a thin film, such as polyethylene, vapor barriers are used to retard or prevent water vapor diffusion into a wall, ceiling or floor during the cold winter.

https://www.doityourself.com/stry/how-to-install-a-vapor-barrier-over-fiberglass-insulation

It is important to note that insulation and vapor barrier are always installed facing the living space and never the other way around. This is because you want to keep the moisture out. First install the fiberglass insulation between the studs and then apply the vapor barrier over the installed fiberglass insulation.

https://homeguides.sfgate.com/install-poly-over-insulation-51602.html

The special paper lining one side of the insulation is sufficient to block moisture and air. Some builders choose to attach a separate vapor barrier even with faced insulation, however. It doesn't hurt anything. The result, when finished, is a super-insulated wall with a foam vapor barrier instead of sheet plastic.

https://homeguides.sfgate.com/use-plastic-vapor-barrier-walls-27385.html

The standard installation of a plastic vapor barrier is between the studs and the drywall, but there are some exceptions to this. In exterior walls that are below-grade, like basement walls, plastic should not be used at all.

https://www.inman.com/2012/02/01/vapor-barrier-tips-walls-floors/

In simple terms, a vapor barrier is a material that won't allow moisture to pass through it, such as plastic sheeting. It's designed to stop the moisture before it can enter the wall cavities. There are two basic types of vapor barriers used with exterior wall insulation. The most common is paper-faced insulation.