Wall Insulation: How to Insulate Your Walls

In exterior walls, kraft-faced fiberglass insulation helps control temperature and humidity inside the structure. But insulation also has a role in interior walls. Woven between 2x4 studs on 2x6 plates, unfaced fiberglass helps deaden sound between rooms. Staggered studs 8 inches on center provide standard 16-inch spacing on each side of the wall.

One of the worst aspects of installing fiberglass insulation is that loose particles can be extremely irritating. Protective clothing is one line of defense: long pants and sleeves, collar and cuffs buttoned. Choose a dust mask especially designed to filter fiberglass particles. Thin leather gloves block irritants while still permitting you to handle tools easily. As soon as you've finished installation, take a shower, using cool water at first to close your pores so the fibers don't penetrate your skin. Wash work clothes in a separate washer load, using hot water and an extended wash cycle.

Another way to avoid discomfort is to select insulation that's designed to minimize itching. One product utilizes curled fibers that are less likely to irritate, and another type sheathes the insulation in a plastic sleeve.

Prestart Checklist

Time
1/2 to 1 hour for an 8-foot wall

Tools
Scissors, staple gun

Skills
Stapling, cutting thick material

Prep
For fiberglass insulation, wall should be framed; utilities installed

Materials
Fiberglass insulation, 1/4-inch staples

Fiberglass Rolls and Batts

Fiberglass insulation comes sized to fit between studs that are either 16 or 24 inches on center. You can buy it in rolls or in batts that are precut to the length of stud bays. For sound control, the paper facing is not necessary but provides a convenient flap for stapling.

Facing in the Right Direction

If you are installing fiberglass insulation in outside walls, pay attention to the paper facing. The facing is a vapor retarder, meant to slow the migration of water vapor through the wall. If warm, moist air from inside a house travels through the wall, it will condense when it hits the cold sheathing on the outside. If the sheathing is damp from condensation, it eventually wets the insulation, decreasing its effectiveness. Damp sheathing also is prone to rot. If the outside air is warm and the inside air is cool, the process works in reverse, causing condensation on the drywall. If you live in a climate where you heat in the winter, place the paper toward the inside of the house. If you live where air-conditioning is used more often than heat, face the paper barrier to the outside of the wall.

Adding Soundproofing

Weave a continuous roll of fiberglass insulation between staggered studs, using insulation designed for 2x4 walls. Weave loosely to fill the cavity but tightly enough so you won't have to compress the insulation when you install drywall. When you reach the end of the wall, cut off the insulation. Weave additional lengths of insulation in the same manner on top of each other until the wall is filled.