Blown In Insulation Over Batts

The r factor of blown in fiberglass is usually 2 3 to 2 8 per inch of material.

Blown in insulation over batts.

Blown in insulation thickness can vary in an attic space. Batt or rolled insulation or blown loose fill insulation fiberglass or cellulose can be installed on top of old insulation. Blown in varieties however typically reach a peak of around a 2 8 r factor. Compared to blown in insulation batts can reach a resistance rating r factor of over 3 1.

The r value can be reduced if the insulation is squashed or flattened. This light as air insulation is manufactured from glass that is heated to a liquid and then spun. Blown in insulation often is a combination of loose fiberglass and treated cellulose fibers. Find out how to install unfaced insulation correctly over blown in insulation.

The depth and thickness of the blown insulation affect the r value. 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. The insulation usually is blended and provides an r value ranging from around 32 to 38 per square foot. Loosely blown fiberglass alone carries an r value of about 22 to 27 per square foot.

Insulation should be rolled out perpendicular to the joists and unfaced rolls should be used. Disadvantages of batt insulation. This will lead to non uniform r values. Rolled insulation should not be tacked down.

There are three types of blown in insulation.