PURPOSE: To obtain a roof decking material applicable to the base of a sloped roof, stable to the temperature variation between high and low temperatures and capable of constantly keeping the nail-hole sealing performance.

CONSTITUTION: A tacky adhesive coating layer having a thickness of ≥0.5 mm and composed of 100 pts.wt. of straight asphalt, 15-25 pts.wt. of blown asphalt, 50-110 pts.wt. of styrene-based synthetic rubber, 35-75 pts.wt. of a process oil and 30-70 pts.wt. of a tackifier resin is applied to the lower surface of an asphalt-impregnated base material having a coated asphalt layer and an antitack layer on the upper surface of the base material.