GreenGuard Q350 Fanfold Underlayment

When every penny counts, you can rely on the performance of one of our most economical fanfold siding underlayments. The 0.3" Q350 is made of extruded polystyrene foam (XPS). Designed to be used as a “leveling board”, with crease-fold hinges, it adds insulation and moisture protection during installation of new vinyl siding over old siding. It is configured in fanfolded bundles 4’ x 48’.

Product Highlights