Slate Roof System

What Is Slate Roof System?

Slate is quarried stone split into shingle-sized pieces and nailed to the deck, and good slate lasts 75 to 150 years or more — routinely outliving the copper or steel flashings, the fasteners, and the underlayment installed with it. That inversion drives everything about slate work: an aging slate roof most often needs its valleys, flashings, and failing nails addressed while the stone itself is sound, and wholesale replacement of good slate because of flashing failure is a costly mistake. Individual broken slates — from hail, foot traffic, or sliding after a nail fails — are replaced one at a time using a slate ripper and hook or hidden strap, a hand skill general roofing crews rarely carry; walking a slate roof without staging breaks more than it fixes. Slate is also heavy — roughly two to four times asphalt per square — so structures must be framed for it, which is why synthetic (polymer composite) slate exists as a lighter, hail-rated alternative with a similar profile at lower weight and cost.

Important Distinction

Note: On an old slate roof the slates usually outlive everything else: most 'slate roof' problems are actually failed nails, flashings, or underlayment — and walking on slate to inspect it breaks slates.

Also Known As

These are the search terms and phrases that commonly refer to this topic, so you can find it however you describe it.