Can a tile roof be pressure washed?

Gently. One concrete tile maker recommends plain water at no more than 1,200 psi, with a cleaner added only in the weakest solution that works and only if it is compatible with concrete, since some products shift the tile's pH or etch the surface. HomeGuide notes that roof cleaning trade groups advise soft washing tile instead.

Does the black algae damage my roof?

It depends on the roof. A concrete tile maker says algae and mildew don't harm the tile's integrity, so cleaning tile is mostly about looks. On asphalt shingles, ARMA treats it as discoloration and warns that a power washer, brush or broom will damage the shingles, so the cleaning method matters more than the streaks.

How often should a roof be cleaned?

HomeGuide suggests every one to three years, more often in rainy places or under heavy trees. ARMA adds that bleach cleaning on shingles is temporary and the streaks may come back. HomeGuide suggests a yearly cleaning for homes under a thick tree canopy.

Roof Cleaning in Pompano Beach, FL

Typical cost: cost guides put most roof cleanings at $250 to $600, with soft washing of tile or shingles at $0.15 to $0.60 a square foot
Time on the roof: 2 to 5 hours for an average house, a full day for a large or steep roof
Shingle method: a bleach-and-water solution left on 15 to 20 minutes, then a gentle rinse, with no power washer
Tile pressure limit: water only, never above 1,200 psi, in one concrete tile maker's guidance

Ring Pompano Beach Roofers and a roof cleaning request goes to a roofing company in the area, with no fee for the call. Roof cleaning here is mostly about the dark streaks that algae leaves on tile and shingles, and the right method depends on the roof: a soft wash for tile and asphalt, a mild detergent for painted metal, a chemical wash for flat membranes.

Roof Cleaning Methods by Roof Type

Low-pressure spray of cleaning solution washing dark algae streaks off a concrete S-tile roof

Soft Washing Concrete and Clay Tile

A concrete tile maker's guidance is to use plain water, never above 1,200 psi, and add a cleaner only in the most dilute solution that works. The cleaner has to be compatible with concrete, since some products change the tile's pH or etch its surface. Cost guides price soft washing tile at roughly $0.15 to $0.75 a square foot. Cracked or slipped tile found during the wash is a repair, covered on tile roofing.

Black algae streaks running down a gray asphalt shingle roof below the ridge

Cleaning Shingle Roofs Without Pressure

The black streaks are usually Gloeocapsa magma, an algae ARMA says is most widespread in the Gulf States and along the Eastern Seaboard. ARMA's bulletin sets out the method:

Liquid household bleach and water, gently dispersed on the roof
Left on for at least 15 minutes and no more than 20
Rinsed off by gently spraying with water
No power washer, brush or broom, which strip granules

The shingle maker has to approve any other chemical. The cleaning is temporary, so at the next re-roof, ARMA suggests algae-resistant shingles (see shingle roofing).

Water from a garden hose rinsing dust and salt film off white standing seam metal roof panels

Cleaning Metal Roof Panels

Cost guides list metal as the one roof that can take a pressure wash, at $0.20 to $0.70 a square foot. A metal panel maker's own care guide is gentler: a freshwater rinse with a garden hose, a 5% solution of non-bleach detergent with a cloth or soft brush for stubborn dirt, and no wire brushes or abrasives on the paint. It also warns that misused cleaning agents may void the finish warranty, so ask what the cleaner plans to put on the panels before work starts.

A worker seen from behind washing a white flat roof with a low-pressure wand near a parapet

Flat and Coated Roofs

Rubber membranes and tar-and-gravel roofs get a chemical wash at about $0.20 to $0.30 a square foot, according to Fixr. A white membrane or coated roof is washed with care around seams and flashing. Cleaning before a recoat is part of the coating job, and in the HVHZ code applying a coating counts as roofing maintenance (see roof coating).

A roofer's gloved hands pressing on the rubber pipe boot flashing of a vent on a gray shingle roof

Why Pompano Beach homeowners call Pompano Beach Roofers

Calling or sending the form costs you nothing
Your request goes to one roofer, not a list of bidders
Ask for tear-off, deck work and the permit on one itemized quote
Get the roofer's CC or RC license number and check it yourself

What Roof Cleaning Costs and What Changes It

HomeGuide's national average is $440, with most jobs between $250 and $600 and a low of about $150 to a high near $1,000. Fixr's range runs higher, $450 to $700 for most jobs, or $200 to $1,200 for a 2,000 square foot roof. The add-ons:

Height
Another story or a multi-level roof adds about $0.10 to $0.20 a square foot.
Pitch
A steep roof adds about $0.15 to $0.20.
Salt and sand
Guides note roofs near the sea take longer to clean, which matters for homes close to the beach.
Gutters
Gutter cleaning runs about $110 to $185, and many companies discount it on the same visit.

Questions to Ask a Roof Cleaner

What pressure will touch the roof?
For shingles the answer should be none; for tile, water no higher than the tile maker's limit.
Which chemical, how strong, and who approved it?
ARMA wants the shingle maker's approval for anything beyond bleach and water.
How are the plants protected?
Most companies tarp the landscaping, and ARMA warns the solution can harm the landscape.
Who goes on the roof?
A wet, treated roof is slippery, and ARMA recommends trained professionals.

See roof maintenance for the twice-a-year checks that go with a clean roof.