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.

Similarly one may ask, does fiberglass insulation need a vapor barrier?

Like other batt-type insulation, fiberglass has a predictable R-value if not compressed but is difficult to fit around obstacles without leaving gaps. In most climates, it needs a vapor barrier.

Likewise, where should attic vapor barrier be placed? The vapor barrier is always installed facing the heated side of the wall or ceiling, because that's where the moisture is coming from.

Beside above, can you put plastic over insulation in attic?

Plastic vapor barriers should only be installed in vented attics in climates with more than 8,000 heating degree days. You can forego the plastic and use a vapor retarder (kraft-faced insulation or latex ceiling paint) in all other climates except hot-humid or hot-dry climates.

Should I put a vapor barrier on my ceiling?

If you live in an area with sustained freezing temperatures, you should have a plastic vapor barrier between the drywall and the studs, wherever "warm meets cold" (exterior walls, top floor ceiling).

Is vapor barrier required by code?

The International Residential Code (IRC) requires either a Class I or II vapor retarder on the interior side of frame walls in climate zones: 5, 6, 7, 8 and marine 4 (see climate zone map).

Should you put plastic between insulation and drywall?

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.

Should I put plastic over my insulation?

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.

What is the purpose of a vapor barrier on insulation?

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.

Can I use plastic sheeting as a vapor barrier?

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.

Is Fiberglass Insulation mold resistant?

Fiberglass, a non-biodegradable substance is resistant to mold. With its sharp, ground glass, mold spores puncture before they can attach to it. Mold can grow on the fiberglass insulation backing, which is made of paper and is a mold food source. Fiberglass insulation without backing may be the best choice.

Which is better foam board or fiberglass insulation?

Foam insulation, whether it's in the form of foam board sheets or spray-on insulation, requires a smaller amount of material to achieve the same amount of insulation. A thicker application of fiberglass, however, can prove to be a bit more efficient.

How do you properly insulate?

Transcript
  1. Get your stud and joist dimensions.
  2. Choose an insulation type.
  3. Cut batt insulation to size.
  4. Make sure insulation fits tight against framing.
  5. Staple tabs (if present) on inside of framing.
  6. Tape any seams or torn kraft-faced insulation.
  7. Don't block air vents with ceiling insulation.

Do vapor barriers cause mold?

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.

How important is vapor barrier in attic?

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.

How do you vapor barrier an attic?

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 insulation (fiberglass or cellulose) is then placed on top of the drywall with no vapor barrier above or below.

What happens if you don't use vapor barrier?

If water vapor diffuses or infiltrates into the wall cavity and finds the cool surface, moisture problems can occur. Of course, you can have moisure problems here even without the exterior vapor barrier because of what Bill Rose calls the rule of material wetting.

Should attic insulation be faced or unfaced?

Attic insulation is available with and without a paper facing. The facing contains a thin layer of asphalt, which acts as a vapor barrier to block moisture. Unfaced Insulation: When adding more insulation to an attic that already has insulation, use unfaced insulation.

What is the best type of insulation to use in my attic?

From a performance standpoint, the best type of insulation is spray foam. There are two types; closed-cell and open-cell, aka 2-pound and ½-pound, respectively. They have insulation values of approximately R-6.5 and R-3.6 per inch, respectively.

Should I remove attic insulation?

The Insulation Should Be Removed When It's Water Damaged It also will lose its effectiveness at slowing down the transfer of heat into your home once it's wet. If a small area was affected, only that portion should be removed, the entire attic insulation does not have to be removed.

When should you replace attic insulation?

Insulation should also be replaced, in some cases sooner than 15 years, if it is no longer doing its job properly. You'll know it needs to be replaced if there are insulation leaks or if it is peeling from the walls.

Why do attics need to be vented?

In cold climates, the primary purpose of attic or roof ventilation is to maintain a cold roof temperature to control ice dams created by melting snow, and to vent moisture that moves from the conditioned space to the attic (ventilation acts to bypass the vapour barrier created by most roof membranes).