Tile Roof: Cracked vs Slid vs Broken Underlayment Decision Tree

Why this matters

Tile roofs leak for reasons the visible tile rarely shows. The tile is a rain-shield; the underlayment is the waterproofing. A cracked tile is often a cosmetic issue while the customer's actual leak is the 28-year-old felt underlayment that finally gave up two bays away. A slid tile can be a wind event or a fastener failure; the conversation with the insurance carrier is different for each. The decision tree below separates cracked vs slid (cosmetic and replaceable in hours) from underlayment failure (a full or partial relift, days to weeks of work, the conversation that pays for the truck).

Symptom presentation

The homeowner reports a leak under a tile roof or a tile out of position seen from the ground or driveway. Up close you see one of:

• A clean tile crack with both halves still on the deck (often hailstone or foot-traffic damage)
• A tile shifted downslope with the upper edge exposed, sometimes only at the headlap
• Multiple tiles displaced along a slope (wind or sliding sequence)
• An interior leak with no obvious tile damage from the surface walk (the underlayment is the failure point)

Quick checks before climbing

Tile roofs are pedestrian-unfriendly and damage easily under careless foot loading. Walk only on the headlap, not the field, and follow the manufacturer's load-bearing pattern (concrete tile typically rated to 250 lb point load on the headlap; clay tile lower, 200 lb at the same point). Captures before the climb:

• Roof age and product. Original concrete tile averages a 50-year functional life; clay barrel tile commonly 75 years. Underlayment underneath averages 20 to 30 years and is the limiting component.
• Recent wind event. ASCE 7 design wind speed for the location and the tile attachment method (mortar set, foam adhesive, nailed, screw + clip per high-wind areas).
• Roof slope. IRC R905.3 requires concrete tile at 2.5:12 minimum slope with double underlayment, 4:12 with single. Clay barrel tile typically requires 3:12 minimum.
• Underlayment type and age. 30 lb felt, polymer-modified bitumen, or synthetic. Pull a corner tile near a known leak to check.
• Whether previous "repairs" included foam adhesive, mortar bedding, or sealant that may have hardened and cracked the tiles they were meant to hold.

Isolation tree

Branch A: cracked tiles, no leak

A cracked tile with both halves still on the deck and underlayment intact below is a cosmetic and wind-resistance issue, not an active leak source. Tile cracks come from:

• Hail (functional impact damage, claim-eligible if part of a documented storm)
• Foot traffic from a tradesperson who did not walk the headlaps (HVAC service, antenna installer, painter)
• Original mortar or foam adhesive contracting and prying the tile (common on hot-set installs after 15+ years)
• Manufacturing flaw (rare, bounded by production lot)

Replace cracked tiles with color-matched stock. On older roofs the original color is discontinued; either pull tiles from a hidden slope to repair visible slopes and replace the hidden area with the closest available match, or paint the new tiles in a manufacturer-approved coating to match (acrylic concrete-tile coatings are common in Florida and California).

Branch B: slid tiles

A tile that has shifted downslope is one of three things:

• Wind uplift exceeded the tile attachment capacity (wind event, often claim-eligible)
• The fastener (nail, screw, clip, or adhesive) failed independent of wind (gradual failure, owner's repair scope)
• The tile below was already missing or broken and the upper tile slid because its bearing surface vanished

Walk the slope at noon. Look at the headlap line; a slid tile creates a gap and exposes the underlayment. Photograph the exposed underlayment, then lift the slid tile to inspect the fastener. A broken or pulled fastener is an attachment failure. A still-tight fastener with the tile shifted around it points at tile breakage at the nail hole.

In wind-exposed areas (ASCE 7 design wind speed 130 mph and up), the attachment method must meet FBC TAS 100, 101, 102 or equivalent. Roofs installed before the post-Andrew (post-1992) Florida changes may not meet current code, and a wind-event scope often includes a code-upgrade conversation.

Branch C: broken or end-of-life underlayment

Interior leak with no visible tile damage at the leak location. Lift tiles in the suspected leak zone. The underlayment underneath shows one or more of:

• Brittle, cracked, or torn felt that breaks at finger pressure
• Tar bleed where the felt has volatilized its asphalt and lost its waterproofing
• Visible deck wood through the underlayment (mechanical damage from prior tile work, animal damage, or simple decomposition)
• A clear water path: stains converging at one penetration, lap, or fastener

Underlayment failure is the dominant cause of leaks on tile roofs older than 20 years. The conversation moves from spot repair to relift (remove tiles, replace underlayment, replace tiles using existing stock plus salvage from hidden areas). Relift labor on a typical residence runs days to weeks; the tiles themselves are reusable if handled correctly.

Confirming diagnosis

Cracked tile, no leak: visible crack, both halves on the deck, underlayment under the tile dry. Hose test at the cracked area produces no interior drip.

Slid tile, no underlayment damage: tile shifted, underlayment intact and not torn, fastener failure or wind-uplift cause. Hose test through the gap produces no interior drip if the underlayment is intact.

Underlayment failure: interior leak, lifted tiles reveal degraded underlayment, hose test reproduces the leak with water applied to underlayment exposed to weather (not just the tile surface).

Remediation

Cracked tiles: replace with color-matched stock or paint-matched substitution. Set per original installation method (mortar, foam, nailed, or screw + clip). Document for the warranty file and discuss attic ventilation if the broken tile pattern matches heat-stress cracking.

Slid tiles from wind: re-secure all tiles in the affected slope and inspect adjacent slopes for marginally attached tiles. If the slope was a high-wind exposure and attachment is not to current code, walk the customer through the upgrade option. Document the wind event with NOAA data for any insurance scope.

References

• IRC 2021 Section R905.3 Clay and Concrete Tile Roofing
• ASCE 7-22 Wind Loads, Components and Cladding for low-rise buildings
• Florida Building Code Test Application Standards TAS 100, 101, 102 (wind uplift on tile)
• ASTM C1167-11 Standard Specification for Clay Roof Tiles
• ASTM C1492-20 Standard Specification for Concrete Roof Tile
• TRI/WSRCA Concrete and Clay Tile Roof Design Criteria Manual for Cold and Snow Regions
• NRCA Roofing Manual: Steep-Slope Roof Systems, 2022 edition, tile chapter