Q: I am estimating a job that calls for loose-fill insulation to be placed in hollow concrete masonry walls. How do I calculate the amount of insulation needed to fill the cores?

A: This table lists how much insulation is needed for various types of masonry walls. About 28 cubic feet of loose-fill insulation are needed to fill 100 square feet of an 8-inch hollow lightweight concrete block wall. The insulation triples the R value of the wall.
VOLUME OF INSULATION NEEDED TO FILL CORES OR CAVITIES OF MASONRY WALLS
Cavity Wall Width of
Cavity
(inches)
Cubic Feet of
Insulation Per
100 Square
Feet of Wall
2 16.7
2 1/2 20.0
4 33.4
Single-wythe
Hollow Concrete
Masonry Wall
Wall
Thickness
(inches)
Cubic Feet of
Insulation Per
100 Square
Feet of Wall
6 19.0
8 27.6
10 35.0
12 50.0

Source: "Estimating Concrete Masonry," NCMA-TEK 14, National Concrete Masonry Association, 2302 Horse Pen Road, Herndon, Virginia 20070.