How to Insulate Basement Walls When Studs Are Already Up

Measure the distance between your wall studs. Buy insulation that is sized to fit this gap. Most wall studs are placed either 12, 16 or 24 inches apart, and fiberglass rolls are sold to fit these dimensions.

Count the number of spaces between wall studs. Measure the height from the basement floor to the ceiling. Multiply this height by the number of spaces. The result is the total length of insulation you need. Buy enough rolls to equal or exceed this length.

Put on protective eye goggles, a dust mask and work gloves. The eye goggles should be vented to prevent fogging up, but the vent holes should be as small as possible to prevent fibers from getting in. Wear clothing that covers your whole body. An ordinary hardware store dust mask is sufficient for this job, but be sure it is fitting properly.

Place the roll of insulation on a wide, clear area of floor. Use the utility knife to cut open the plastic wrapping around the insulation while taking care not to cut the insulation. The insulation will expand when released from its package.

Cut a length of insulation as long as the basement wall is tall. Place it in one of the gaps between studs. Press it into the space, and then pull it forward a bit to fill the depth of the cavity. This will fluff it up and make it more effective. Make sure the vapor retarder is facing the interior space.

If the roll is not sized for your wall cavities, you need to cut it to fit. Trim the piece you cut until it is 1 inch wider than the distance between the studs.

If the insulation has flanges on the sides of the facing, you can elect to staple the flanges to the studs on either side of the cavity. This will hold it more securely in place. However, friction alone should be enough to do the job.

Cut additional lengths to fill the remaining wall cavities and install in the same manner as the first length of insulation.