One of the easiest ways to insulate your attic is with STYROFOAM™ Brand Insulation or EPS rigid insulation. Universal Foam Products will provide you insulation in any thickness you need (the R-Value is either 4 or 5 per inch depending upon the material you choose) and we will cut to widty – 14-1/2″ if your joists are spaced 16″ on center or 22-1/2″ if your trusses are 24″ on center. Rigid insulation is easy to install (not messy like fiberglass). It is light weight and economical.