On average, roofers charge by the square, which is a 10-by-10 foot patch of the roof. Average residential roofs require between 22 and 34 squares.
There is also a charge for removing the old roof, and typical fees run between $100 and $150 per square. Double and triple roofs cost more to remove, as well as extremely high or steep roofs.
Flashing, trim, gutters and vent covers carry additional charges, too, with costs for shingling over an existing roof costing less. Keep this in mind, though, that shingling over an existing roof omits repairs to a damaged roof deck. Roofers like to apply newer synthetic membranes to offer better protection against ice and rain damage. The new membrane is not part of the process when shingling over an existing roof.
Metal roofs cost between $500 and $1800 per square. The most common selection by homeowners is corrosion-resistant metal that costs between $700 and $1,000 per square. Natural slate tile ranges from $800 to $1,600 per square.
The final cost of a slate roof is often more than $4,000 for high-end slate and an intricate installation pattern. Ready-made clay tiles cost between $600 to $800 for an average-sized home. Custom-made premium grade clay tiles can sometimes cost up to $4,000 per square.