Installing fiberglass batts

For R-value requirements, consult your local building code. Inspect all walls and ensure all cavities where insulation will be installed will have 6 sides after the wall finish is installed. That means there will be an exterior sheathing, such as insulation board or OSB, wood or steel studs on the four sides, and finally the wall finish on the interior.

Because loose-fill or batt insulation on the attic floor and batts installed under floors are not exposed to significant air movement, they do not need to be covered on the exterior side.

Minimizing air infiltration is dependent on the air barrier system and not the insulation type. The most important thing to do before installing fiberglass and rock wool batts in walls, and other parts of the building envelope, is to make sure there is an effective air barrier system in place. Weather-resistive barriers may be taped or sealed with caulking, rigid sheet-good materials may be sealed with caulk or specialty sprayed-on air sealing systems.

Having a second air barrier in place, such as sealing the interior finish i. 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. Moisture buildup in the attic is a concern because it can condense into water, often causing mold. So if it is installed upside down, the paper moisture barrier can actually keep moisture in-between the paper and the sub-flooring. This can lead to mold issues, as well as structural deterioration. Also, the paper is flammable so not properly installing it can create a fire hazard.

Vapor barriers are usually best installed on the side of the wall that experiences the hotter temperature and moister conditions: the inner surface in colder climates and the outer surface in hot, humid climates. Removing old insulation and replacing it with new ones will not only rid your home from any rodent infestation and mold, but also improve its energy efficiency and overall air quality.

Blow-in insulation is quite comparable in cost and R-value when compared to fiberglass batts or blankets. If the fiberglass insulation has no paper at all, it is unfaced and has no vapor barrier and does not need taping.

The friction of the fiberglass insulation material against the rafters, baffles and plywood or wood slats is typically enough to hold it in place. Both types are available faced with kraft paper or aluminum foil, which serve as a moisture barrier. Unfaced insulation is often laid over existing insulation to increase home energy efficiency. When you install faced insulation, the moisture barrier paper or foil must face toward the heated and cooled side of the room, so when insulating between wall studs, be sure the paper or foil moisture barrier faces toward the room.

The R-value of insulation tells you its insulating value. It is a measure of thermal resistance that prevents the transfer of heat. The higher the R-value number, the thicker the insulation is and the better it insulates. The exact R-value you need depends on several factors, including the size and construction of your home and the geographic area in which you live.

As a general rule, homes with 2-by-4 framed walls require R insulation, and 2-by-6 framed walls require R insulation. The standard R-value for insulating attics is between R and R Walls are typically insulated with faced batt insulation because it comes precut into strips that fit standard 8-foot-tall walls.

However, faced roll insulation is also perfectly acceptable. Caution: Installing fiberglass insulation exposes you to fine glass fibers, which are irritating to the skin, eyes, and lungs. Whenever you handle the insulation, wear long pants, a long-sleeved shirt, tight-fitting eye goggles, gloves, and a dust mask, or better yet, a dual-cartridge respirator.

To keep the itchy glass fibers from sticking to your neck, sprinkle baby powder onto the exposed skin around your shirt collar. There are a few different ways to slice through insulation, but the simplest method for do-it-yourselfers is to use a straightedge and utility knife as shown in the photo below. Extend the blade out about 3 inches, then tighten the locking knob. The extra-long blade makes it much easier to slice through thick insulation.

Just be careful with this super-sharp, long blade! That creates an energy-wasting void behind the obstacle and compresses the insulation. Instead, split the insulation, starting from whichever end of the insulation is closest to the obstacle.