Pressure washing roof tiles can do more harm than good. A high-pressure stream can crack clay and concrete tile, erode the colored surface, loosen ridge mortar and drive water up under the tile laps onto the underlayment. The roof may look clean afterward while hiding damage that shows up as a leak months later.

Why homeowners pressure wash tile roofs

The motive is understandable. Along the coast in Huntington Beach, Laguna Beach and San Clemente, the marine layer keeps north-facing tile damp, and algae, lichen and dark streaks follow. Inland, dust and pollen dull the color. A pressure washer seems like the fastest fix, and door-to-door cleaning crews often offer it.

If your tile roof was recently power washed and you're not sure what shape it's in, book a roof diagnosis online before the next rain tests it.

How pressure washing roof tiles causes damage

Cracks from pressure and footsteps

Tiles are designed to shed rain falling from above, not to absorb a concentrated jet at close range. The stream can crack older or thin tiles, especially at the nose where they overlap. And the person holding the wand has to walk the roof, which breaks tiles on its own. Our guide to cracked roof tile repair explains what happens next.

Stripping the surface

Concrete tiles are either colored with a surface slurry or coating, or colored all the way through and finished with a sealer. Either way, high pressure can erode that outer layer and expose the rougher, more porous concrete beneath. The roof may look blotchy, absorb more moisture and grow algae faster than before. Clay tiles with glazed or fired surfaces can chip.

Water forced under the tiles

This is the damage people don't see. Aiming the stream upward, or washing across the laps, pushes water past the tile overlaps and into the battens and underlayment in a direction rain never travels. On an older roof with worn underlayment, that water can reach the deck and the attic.

Why older underlayment makes it worse

On many Orange County tile roofs, the underlayment beneath the tiles is decades old. It may shed normal rain but fail when water is blasted against it, so the first sign may be a ceiling stain long after the washing crew has gone.

Loosened ridges, hips and flashing

Mortar and pointing along ridges and hips can crumble under pressure, and loose ridge tiles are then easy for Santa Ana winds to lift. Sealant at flashing and around vents can also be blown out.

Signs your tile roof was damaged by power washing

  • Tile chips, grit or mortar fragments in gutters and on the ground.
  • Cracked, slipped or missing tiles, often in walking paths across the roof.
  • Uneven color, with patchy or pale areas where the surface was eroded.
  • Loose or broken ridge and hip tiles.
  • Damp spots, stains or a musty smell in the attic in the days after washing.
  • A first-rain leak in a spot that has never leaked before.

What pressure washing does to different tile types

Concrete tile

Concrete tile is the most common tile roof in Orange County tract neighborhoods. It is heavy and strong in normal use, but its surface is the part that suffers first under a pressure washer. Once the surface is eroded, the tile absorbs more water, stays damp longer and may lose strength over time.

Clay tile

Clay barrel tiles, typical of Spanish-style homes in San Clemente and San Juan Capistrano, are fired and dense but can be thin and brittle, especially older ones. They crack under point loads and chip at the edges when hit with a concentrated stream.

Mortar-set tile

Roofs where ridge, hip or rake tiles are set in mortar are especially exposed, because the mortar is softer than the tile and washes out first.

When to book an inspection

If you see any of those signs, or if you simply know the roof was washed at high pressure, a professional inspection is worth scheduling before the rainy season. Our roof inspection service uses our 4-Phase Roof Inspection, which ends with a full written report on the tile, ridges, flashing and any moisture below. Our T.E.A.M. Certified technicians know where to step on tile so the inspection doesn't add damage of its own. We've served Orange County since 1993 under St. Lic #1137524.

What repairs usually look like

Most findings are small: replacing cracked tiles, resetting slipped pieces and repointing ridges. If the inspection shows water has been reaching worn underlayment, a lift-and-relay may be recommended, where tiles are removed, new underlayment is installed and the good tiles are reset. We're "The No-Felt Company," so replacement underlayment is synthetic.

Safer ways to keep tile looking good

If appearance matters, keep the approach gentle. Clear leaves and debris from valleys and gutters so moisture doesn't linger. Trim branches that shade the roof and drop debris. If you want the roof cleaned, ask any cleaning company how they avoid walking the field, what pressure they use and how they keep water from being driven under the tiles. Our article on tile roof cleaning in Orange County covers what to ask. A little discoloration is cosmetic; a cracked tile or soaked underlayment is not.

Frequently asked questions

Is it ever okay to pressure wash roof tiles?

High pressure carries real risk on tile. Many tile manufacturers and roofers advise against it. Low-pressure methods and professional advice are safer.

My roof was power washed and hasn't leaked. Should I still worry?

Leaks from forced water or damaged underlayment often appear only with the first heavy rain. An inspection now gives you a clear picture before then.

Can faded concrete tiles be restored?

Surface wear is mostly cosmetic. What matters most is that tiles aren't cracked and the underlayment beneath them is still sound.

Worried about what a power wash did to your roof? Call 1-888-346-7663 or book your roof diagnosis online. We'll inspect the tile, ridges and attic and give you a written report showing exactly what, if anything, needs attention.