ASTM D-6380 TYPE II 90# - ASTM-D6380

ASTMD6380 Class M

An asphalt roofing felt made of a specially formulated organic sheet, which has been fully saturated with waterproofing asphalt. This product is strong, flexible and impervious to water penetration, but will allow water vapor to pass through at a restricted rate.. Preconditioned to help it lay flat and remain stable after installation on a roof deck. This underlayment asphalt felt is designed to be used as an all-purpose protective waterproof sheet in construction projects. Ca be installed as a temporary roof cover during house construction and then serve as a permanent shingle underlayment after shingles are installed. As a shingle underlayment it functions to restrict vapor movement from the wood deck and attic to the underside of the shingles thus preventing condensation and as a barrier to wind-driven moisture which may get past the shingle. Can also act as temporary protection if shingle blow-off occurs. May also be used as a waterproof breather sheet on side-walls beneath outer finish.