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Slate and clay tile roofs, though far less common today than asphalt shingles, still cover a meaningful number of older homes and institutional buildings across the upper Midwest, and they present evaluation challenges that differ substantially from a typical shingle roof inspection. Natural slate is a metamorphic stone split into thin sheets, and its service life, often measured in many decades when properly installed and maintained, means the slate itself frequently outlasts the fasteners and flashing holding it in place. When damage occurs on a slate roof, distinguishing damage to the slate material from failure of the fastening system is one of the first analytical steps.
Hail impact on slate behaves differently than on asphalt or metal roofing. A quality slate can withstand a fairly significant hail strike without fracturing, though lower-grade or already-weathered slate can crack or spall under impact that a sound slate would tolerate. Cracked slates sometimes remain in place and functional for a period of time even after fracturing, which complicates dating the damage, since a hairline crack from an earlier storm can propagate and finally fail during a later, unrelated event. Careful examination, including sounding the slate by gentle tapping and checking for movement or looseness, along with attention to the fastener condition, typically forms part of a thorough slate roof assessment.
Clay tile roofs raise a related but distinct set of considerations. Clay tile is more brittle than slate in many cases, and foot traffic during an inspection or repair can itself cause breakage if not handled carefully, meaning inspection methodology matters as much as the findings themselves. Older clay tile profiles, particularly barrel or Spanish-style tiles found on some period homes, may no longer be manufactured in matching color and profile, which affects the realistic repair approach when only a portion of a roof is damaged and an exact match for replacement tiles cannot be sourced.
Underlayment and flashing on these roofs deserve particular attention in a cold climate. The original underlayment beneath a slate or tile roof installed many decades ago has often reached or exceeded its expected service life independent of any storm event, and when a scope of repair is being developed, separating underlayment deterioration from storm-caused damage to the covering material itself is an important distinction. Copper flashing, common on higher-end slate and tile installations of earlier eras, can also show its own patina and wear patterns that need to be read correctly rather than mistaken for storm damage.
Given the specialized nature of slate and tile roofing, contractors qualified to perform this work are less numerous than general roofing contractors, and that scarcity is a legitimate factor when scoping repair timelines and costs. As with other technical evaluations involving legacy materials, the appraisal process focuses on establishing the physical scope and reasonable cost of restoring the roof, while questions about whether a given repair method or material is required or covered under the policy remain with the policyholder and the carrier.
This article is general education about how the appraisal process commonly works. It is not legal advice, and specific procedures can vary by state and policy.
Russ Lis is a working property insurance appraiser and umpire based in Minnesota, serving clients nationwide. Contact Appraisal Resolution.