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.

Foam board insulation is one of the most common types of attic insulation. Also known as rigid foam insulation, it is made from a type of plastic and can be cut to size to insulate an attic.