Composite Wall R-Values Problem # 3

Uploaded by duttoninstitute on 30.05.2012


This is a problem where we have three layers for a wall.
And those three layers are made up of stone, polyurethane
board, and plywood.
The first one is stone, and its thickness is 8 inches.
And each inch of stonewall would provide
an R-value of 0.8.
Therefore, all these 8 inches would provide together 0.64.
And the second layer is made up of 3 inches of

And each inch provides an R-value of 6.25.
Therefore, together all 3 inches would provide an
R-value of 18.75.
The third layer is, again, 3/4-inch plywood.

And it provides an R-value of 0.94.
So all these three together would have
an R-value of 20.33.
Or the composite R-value is 20.33 degrees Fahrenheit foot
square hour over BTUs.