How Effective Is Block Wall Insulation?

Effectiveness

• A block wall may protect against moisture but it is a relatively weak barrier for preventing heat transmission. This is why builders and homeowners commonly fill the spaces in concrete blocks with additional insulation material. Concrete block walls that use polystyrene inserts typically have an R-value between R-1 and R-2, according to the U.S. Department of Energy. This is lower than the R-value, or thermal efficiency, of most commercial insulation products.

Enhancing Insulation

• While block walls don't provide a high degree of insulation on their own, they can accommodate additional insulation that makes them sites for very little thermal transmission. External insulation is the most effective, but must be installed on the outside of the block wall while a home is under construction. Internal basement insulation refers to insulation that is affixed to block walls from the inside. The R-value of the blanket or rigid panel insulation can be added to the R-value of the block wall to determine the total insulation effectiveness of the surface. This means that a block wall can be a highly effective insulator if it includes a high-quality insulation product.

Impact

• Block walls that include little or no insulation allow cold temperatures from the earth to enter a basement, along with natural moisture. This can make a basement cool and damp, raising the need for a heater or dehumidifier to make the space usable as living space or for storage. Adequate insulation allows block walls to keep the basement dry and help it maintain a more consistent temperature. If your basement includes finished living space, insulation will mean lower basement heating bills and more comfort for you and your family.

Sound Insulation

• Block walls also make poor insulation barriers for the transmission of sound waves. The density of concrete blocks allows them to conduct sound rather than stifling it, so a basement media room or living room with block walls will not be an ideal space for listening to music or viewing movies or television. Acoustic panels, which feature textured surfaces that absorb sound waves, can help mitigate the tendency of block walls to reflect sound waves back into the room.