TAMKO^® TW UNDERLAYMENT self-adhering underlayment is a 40-mil thick, flexible, self-adhering, rubberized asphalt sheet membrane with a polymer film on the surface and a removable treated release film on the adhesive side.

TW UNDERLAYMENT is well suited for use as an underlayment where water penetration prevention is required including on metal roofs. TW Underlayment also provides secondary protection against water penetration after installation of a metal roof system. When fasteners penetrate the TW Underlayment membrane during installation, the metal roof system manufacturer's  recommendations should be followed to assure watertight integrity at the fastener penetrations.