so you can multiply the R-value by the thickness of the insulation to get the total R-value of the layer. Fiberglass insulation is made of fine glass fibers that trap air and slow down heat transfer.

Foam board insulation is easy to use and a great DIY way to add some insulation. It comes in standard-size 4×8 sheets and smaller sizes, in thicknesses from 1/4-in. to two inches. Some types of ...