TL;DR: The black streaks on your tile roof are almost always algae, not dirt. It’s biological, it spreads, and it’s fixable. Professional high-pressure cleaning removes it, but tile is fragile, so who’s holding the wand matters. Inexperienced crews and DIY jobs crack tile and push water under it. Cleaning starts at $0.50 per square foot, and most Orange County and San Diego roofs need it every few years.
What’s Actually Growing on Your Roof?
Coastal Orange County and San Diego County are ideal for roof algae: marine layer mornings, humidity, and shade from trees and neighboring homes. Most dark streaking is algae (a cyanobacteria). Moss shows up in shaded, north-facing spots. Lichen looks like crusty patches.
All three hold moisture against the tile, and tile is porous, so it soaks that moisture up. Left alone, the growth spreads and the tile ages faster.
Why the Crew Matters More Than the Tool
This is the biggest mistake homeowners make: treating tile roof cleaning like any other pressure washing job.
- Done wrong: Wrong pressure, wrong angle, or a crew that doesn’t know tile. Water gets forced up under the tiles, the surface gets stripped, and tiles crack under careless foot traffic.
- Done right: A trained crew, controlled pressure, the correct angle, and careful footing. The growth and buildup come off, the tile stays intact, and the roof stays clean for years.
Anyone can rent a pressure washer. Cleaning tile without damaging it takes experience. Ask any company how many tile roofs they’ve cleaned and how they protect the roof, and your landscaping, while they work.
5 Signs Your Roof Needs Cleaning
- Dark streaks, usually running down from the ridge.
- Green or brown patches in valleys and shaded sections.
- Faded, dull tile that looks older than it is.
- Growth in the gutters or heavy debris packed under the tiles.
- An HOA notice, or curb appeal that’s dragging down your home’s value.
Not sure what you’re looking at? Is Your Roof Trying to Tell You Something? covers the warning signs in more detail.
What Does Tile Roof Cleaning Cost in Orange County and San Diego County?
Tile roof cleaning starts at $0.50 per square foot. A 2,500 sq ft roof starts at $1,250.
Where you land above that depends on roof size, pitch, number of stories, how bad the buildup is, and how hard the roof is to access. Anyone quoting a flat number without looking at the roof is guessing. We quote from the actual roof, and you get the price before we start.
For perspective, a new tile roof in Orange County or San Diego County can run $20,000 to $40,000 or more. See why cleaning costs a fraction of replacement.
How Often Should You Clean It?
- Every 2 to 4 years is typical for coastal Orange County and San Diego homes.
- More often if the roof is shaded, sits under trees, or faces north.
- Sooner if growth comes back fast, because it means moisture is sitting on the roof.
A roof that’s kept clean lasts longer and looks better, and it costs far less than replacing tile early. Want a schedule? Read The Ultimate Roof Maintenance Program.
Why Tile Roofs Need a Specialist
Tile is fragile underfoot. A crew that doesn’t know where to step will crack tiles while cleaning them. Roof cleaning is what we do. We know how to move on tile, how to protect your landscaping and windows, and how to rinse without forcing water under the tiles.
FAQ
Will cleaning damage my tiles?
Not when an experienced crew does it with the right pressure, angle, and footing. Damage comes from inexperience and careless foot traffic.
How long does it take?
Most homes are done in a day.
Do I need to be home?
No. We just need access to the exterior and a heads-up about pets and sprinklers.
How long will it stay clean?
Usually a few years, depending on shade and moisture.
Is it safe for my landscaping?
Yes. We pre-wet and rinse plants, and we cover anything delicate.
Should I clean it myself?
We’d advise against it. Walking a tile roof and running a pressure washer up there is how DIY jobs end with cracked tile or a fall.
Follow the crew and see more before-and-afters:
Next up: why roof cleaning demand is surging across Orange County.