Slate Roofing system $22,560 or $14.10 per ft. 2 Quote consists of installing a brand-new all-natural slate roofing system, and underlayment, all blinking, on a ranch design 1,600 sq.ft. Keep in mind, that slate is the heaviest roofing product that needs structural reinforcement. On many residences it is not possible to mount a new slate roofing system in all. Eliminating old timber shingles or shakes will set you back $1.20-- $1.50 per foot.