Progressive Foam. Foam-backed siding isn’t the only option for homeowners who want extra insulation. Fullback siding insulation is available in a range of profi les to anchor vinyl, fi ber-cement, wood composite, steel, and other materials. Fullback products carry R-values of 2 to 3.5 and add rigidity to the siding material for improved performance over uninsulated siding. 800.860.3626.