Products / Styrofoam Brand Deckmate Plus XPS Insulation

Styrofoam Brand Deckmate Plus is an extruded polystyrene (XPS) roof insulation board for conventional low-slope roofs, with smooth high-density skins and a closed-cell structure, which DuPont says is approved for direct- to-deck application under most North American building codes, including fire-classified assemblies, without a separate thermal barrier. The product information sheet prints R-5.0 per inch at 75 degrees F, 25 psi minimum compressive strength, 50 psi flexural strength, 1.5 perm maximum water vapor permeance and flame spread of 25 or less (UL 723), in 4 by 8 foot square- edge boards 2 to 4 inches thick. Its code table lists Factory Mutual approval, ICC-ES ESR-4755 and UL Classification Certificate D-309. DuPont's copy is inconsistent in two places: the Deckmate Plus page and sheet head their test table with the Deckmate Plus FA name, and the low-slope roofing brochure lists 0.1 percent maximum water absorption for Deckmate Plus where the sheet prints 0.3 percent.