Blown In Insulation Over Batts

Blown in insulation thickness can vary in an attic space.

Blown in insulation over batts.

This will lead to non uniform r values. This light as air insulation is manufactured from glass that is heated to a liquid and then spun. The insulation usually is blended and provides an r value ranging from around 32 to 38 per square foot. Rolled insulation should not be tacked down.

The r factor of blown in fiberglass is usually 2 3 to 2 8 per inch of material. Learn how one caller made an installation mistake and increased his chances of mold and condensation when he tried to add unfaced insulation over his blown in attic insulation. Compared to blown in insulation batts can reach a resistance rating r factor of over 3 1. There are three types of blown in insulation.

Blown in insulation often is a combination of loose fiberglass and treated cellulose fibers. The depth and thickness of the blown insulation affect the r value. Find out how to install unfaced insulation correctly over blown in insulation. Batt or rolled insulation or blown loose fill insulation fiberglass or cellulose can be installed on top of old insulation.

The r value can be reduced if the insulation is squashed or flattened. Disadvantages of batt insulation. Insulation should be rolled out perpendicular to the joists and unfaced rolls should be used. Once installed and expanded to the uniform manufactured thickness batts offer a known r factor.

The maximum rating of batt insulation is around 4 2.