Faced insulation is a type of blanket insulation that is typically made of fiberglass. It differs from unfaced insulation only in that it has a vapor barrier (also called vapor retarder) that blocks moisture from moving from one space to another. The vapor barrier is usually made of kraft paper. Faced insulation is sold in rolls or batts that are stapled to joists or beams.
The choice between faced and unfaced installation usually comes down to climate. However, some people in climates where faced insulation is required or recommended choose to buy unfaced and then pair it with a material such as plastic sheeting to form a makeshift vapor barrier. Some professionals argue that strategy is superior.
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Types of Vapor Barriers
There are three classes of vapor barriers, and faced insulation fits into just one of them. This is important to understand because even if you are required by local building codes to install a vapor barrier, faced insulation is not your only option.
- Class I, which includes sheet polyethylene or non-perforated aluminum foil, has very low permeability.
- Class II, which includes faced fiberglass batts or low-perm paint, has low permeability.
- Class III, consisting of latex or enamel paint, has medium permeability.
Keep reading for more detailed information about whether you need a vapor barrier at all and, if so, what class to buy.
The Right Vapor Barrier For Your Region
International building code requires vapor barriers in some regions of the country but not others. At the risk of oversimplifying, the vapor barrier is required in most cold climates but is not required in most warm climates.
For specific information about your region, check out this climate map and find your zone. The International Residential Code (IRC) requires a Class I or II vapor barrier on the interior side of walls in zones 5, 6, 7, 8 and marine 4.
Vapor barriers are not required or prohibited by IRC in zones 1, 2, 3 and 4. However, some experts will tell you they’re a good idea anyway. Just be sure to use only Class II or III barriers in warmer clients, never Class 1.
If all of this is confusing, call your local building department for advice.
Faced Insulation Installation
Faced insulation is used in exterior walls, attics, finished basements, floors and ceilings. It is stapled to studs and joists, unlike unfaced batts. The insulation can also be used to fill cracks around doors and windows, but you’ll need to peel off the facing.
Climate also dictates how the vapor barrier should be positioned. In most cold climates, the insulation should be placed with the vapor barrier facing the outside of the house. In warmer climates, it should be placed facing the inside of the house.
How Much Does Faced Insulation Cost?
Faced insulation ranges in price from $0.50 to $2 per square foot of wall, installed. The price varies based on the R-value (level of energy efficiency), the area of the house where it is being installed and geographic location. A job that costs $0.75 per square foot in one area of the country might cost $2 per square foot in another, so the best way to estimate price is to get quotes from local contractors.
Generally, faced insulation is slightly more expensive than unfaced.
Faced Insulation Pros
- Creates a moisture barrier – Faced insulation controls the amount of moisture that collects in your walls, floors and ceilings. This is important for preventing moisture problems such as mold and mildew.
- Easier to install – The facing material typical makes the insulation easier to handle and attach.
Faced Insulation Cons
- Combustible – Faced insulation should not come in close contact with flames, heating sources, lights fixtures, certain electrical devices and masonry chimneys. Check the package directions or consult a professional if you have questions about whether faced insulation is safe in a certain area.
- Not ideal for adding insulation – If you’re adding new insulation over old insulation, avoid faced insulation. When both the new and old insulation have vapor barriers, moisture can get trapped in between the insulation, causing damage.
Unfaced insulation is another type of blanket insulation, also typically made of fiberglass. Unlike faced insulation, it does not have a vapor barrier that blocks moisture from moving from one space to another. Unfaced insulation is sold in rolls or batts that are held in place by friction, not stapled.
Sometimes, unfaced insulation is paired with plastic sheeting to form a makeshift vapor barrier that some professionals argue is superior to faced insulation. Unfaced insulation is required in some climates – usually colder climates – and not others.
Surprisingly, the lack of a vapor barrier does not affect the R-value of the insulation. Unfaced insulation is no more or less energy efficient than comparable faced insulation. Both are available with varying R-values, as well as in varying lengths and widths.
How Much Does Unfaced Insulation Cost?
Unfaced fiberglass batts usually cost about $0.50 to $1.75 per square foot of wall, including installation. R-value, the area of the home and geographic location are the major factors that influence price. On average, unfaced insulation costs $0.10 to $0.25 less per square foot to install than faced insulation.
Unfaced Insulation Pros
- Great for adding insulation – If you’re adding a layer of new insulation on top of old faced insulation, unfaced is the way to go. When both the new and old insulation have vapor barriers, moisture can get trapped in between the insulation, causing damage.
- Noncombustible – Building codes consider unfaced insulation noncombustible, so it is safer in close proximity to heating sources. Still, always check with a professional if you’re unsure of safe installation procedures.
Unfaced Insulation Cons
- No moisture barrier – Without a moisture barrier, there’s a greater chance that moisture will collect in your walls, floors and ceilings, leading to mold and mildew.
- Harder to install – Unfaced insulation is more difficult to handle because of the lack of facing. It is harder to install evenly, too.