How much does roof cleaning cost?

Nationally, roof cleaning averages about $550, with most jobs falling between $300 and $900. Size, surface condition, and access move the number within that range.

Is roof cleaning priced by the job or by the hour?

Reputable pros quote a flat price by the job, usually built from a per-square-foot rate ($0.20–$0.60 per sq ft) after measuring. A flat quote protects you from an open meter.

What are the black streaks on my roof?

Almost always algae rather than dirt. ARMA identifies Gloeocapsa magma as “probably the most prevalent of several algae species that contribute to discoloration” on roofs. It is a stain rather than structural damage, which is why it sits at the cheaper end of roof-cleaning work — a solution, a dwell, a low-pressure rinse. The streaks run downward because the growth spreads with water running down the slope.

Does moss cost more to remove than algae?

Yes, usually meaningfully more. Algae is a film and comes off chemically. Moss has physical bulk and has to be removed by hand, which means someone on the roof rather than a wand from a ladder. It also matters more: OSU Extension notes that moss on asphalt and metal roofs “can lift shingles and allow water to penetrate and damage underlying layers”. Lichen is harder again and sometimes needs a second visit.

How long does roof cleaning last before the streaks come back?

There is no honest fixed number, because it depends on climate and shade rather than on the wash. Warm, humid, shaded roofs recolonise fastest. OSU Extension’s guidance on moss is the clearest statement of the principle — cleaning alone will not keep growth away if the conditions that grew it are unchanged; letting more sun onto the roof is the durable fix. Treat any promise that it will never return as a sales claim, not a specification.

Can a roof be too far gone to clean?

It can. Heavy lichen cover, widespread granule loss, or shingles already curling mean you are looking at a roofing question rather than a cleaning one, and a wash will not fix — or hide — it. A crew that tells you this and declines the job is doing you a favour. Get a roofer’s opinion before paying for a clean that buys nothing.

Roof cleaning Cost (2026) | Pressure Washing Cost Guide

What roof cleaning costs across the US — by home size and surface, with a fair low/average/high range.

Cost by home size

Home size	Range	Average
Small (under 1,500 sq ft)	$240–$720	$440
Medium (1,500–2,500)	$300–$900	$550
Large (2,500–4,000)	$390–$1170	$715
Very large (4,000+)	$510–$1530	$935

What affects the price

Size & surface area — the biggest driver; most jobs are priced from a per-square-foot rate.
Condition — heavy algae, mildew, oil, or salt film needs more solution and dwell time.
Access & height — second stories, steep roofs, and tight landscaping add labor.
Method — soft washing (siding, roofs) uses cleaning solution and costs a bit more per foot than a plain concrete blast.

Which growth is on your roof — and why it changes the price

“Roof cleaning” is not one job. Four different things discolour a roof, they take different chemistry and different labour, and a quote given before anyone has identified which one you have is a guess. Work out what you are looking at before you call, because it is the single best predictor of where in the $300–$900 band you will land.

What you see	Most likely cause	What it does	Effect on cost
Black streaks running down the slope	Algae — ARMA names Gloeocapsa magma as “probably the most prevalent of several algae species that contribute to discoloration”	Cosmetic in the short term; it is a stain, not a structure problem	Baseline. One solution pass, one dwell, one rinse — the cheapest of the four
Green cushions, thickest along shingle edges and in valleys	Moss	OSU Extension: the moss itself does not directly damage the roof — it “traps soil and debris, holding moisture”, and on asphalt and metal “can lift shingles and allow water to penetrate”	Higher. Physical removal plus treatment, and it is slow, careful work
Flat, crusty grey-green discs stuck hard to the granules	Lichen	Grips the granule surface; it does not lift off with a rinse the way a film does	Highest. Often needs a second visit — and a roof this colonised may be past cleaning
Uniform grey-brown dulling, no pattern	Airborne dirt, soot and pollen	Nothing structural	Lowest. Frequently bundled into a whole-home wash rather than priced alone

The practical rule: a stain gets cleaned, a plant gets removed. Anything with physical bulk on it — moss, lichen — means hands on the roof rather than a wand from a ladder, and hands on the roof is what you are actually paying for.

The most expensive mistake on this page is pressure

The shingle manufacturers’ own trade body is blunt about it. ARMA instructs homeowners to “DO NOT use a power washer or any type of brush or broom to clean algae from the roof surface”, and states elsewhere that you should “never use a pressure washer to clean an asphalt shingle roof as this will cause granule loss and very likely premature failure of the roof system”. Granules are the shingle’s sunscreen. Strip them and you have not bought a $550 cleaning; you have bought a shorter roof life, and the difference between those two numbers is four figures.

That is why every price on this page assumes soft washing — a cleaning solution that does the work chemically, left to dwell, then rinsed at low pressure. ARMA’s own method note is a bleach-and-water solution left on the roof “for at least 15 minutes but no more than 20 minutes”. If a quote is cheap because the crew intends to blast the roof, it is not cheaper. It is a different, worse job wearing the same name.

One honest complication, because flattening it would be dishonest: the guidance is not perfectly unanimous. Oregon State University Extension, writing about moss in the Pacific Northwest, allows that “experienced users may pressure-wash, but improper technique can damage shingles” and steers everyone else to a professional or a long-handled scrub brush. So: the roofing manufacturers say never, a university extension service says experienced hands can, in a specific regional context, on a different organism. What both agree on is that in an untrained hand a pressure washer damages the roof — which is the part that decides your bill.

Four things that legitimately push a roof quote up

Pitch and height. Anything a crew cannot reach from a ladder needs roof access, fall protection and more time. This is usually the largest single line after area.
What is growing, not how dirty it looks. Per the table above — moss and lichen are labour, algae is chemistry.
Roof material. Tile is walkable only in specific places and cracks where it is not; the Tile Roofing Industry Alliance restricts tile to professional low-intensity washing and points homeowners to a licensed roofing contractor. Metal has its own coating limits. Shingle is the cheapest surface to clean, and the least forgiving of pressure.
What is underneath. Roof solution runs off onto plants, and off the property. Landscape protection, pre-wetting and rinsing take real time, and keeping detergent-laden wash water out of the storm drain is the practice EPA’s stormwater best-practice menu is built around — a careful crew builds that into the price. (Whether it is legally required where you live is a local question: the federal program covers municipal storm sewers, construction and industrial sites, and your city’s ordinance is the enforceable version.)

Red flags in a roof-cleaning quote

A price given without seeing the roof — or without a photo. Area, pitch and growth type are the whole quote.
“Pressure washing” used for the roof itself. Ask which it is. A pro who soft-washes will say so unprompted and will usually explain the dwell time.
An hourly rate with no cap. Ask for a flat, not-to-exceed number.
A guarantee that it will never come back. Nobody can sell that — see below.
An offer to install zinc or copper strips on your existing roof as an add-on. ARMA specifically does not recommend adding strips to an existing roof, because it means either exposed nails, which can cause leaks over time, or breaking the shingle sealant bond.
A wash quoted on a roof that is visibly near the end of its life. Cleaning is cosmetic — it removes the growth and adds no service life — so on a roof that is cupping or shedding granules the money buys a look, not a fix. The question bites hardest in Florida, where insurers order the inspection that triggers the call; a Central Florida guide to cleaning versus replacing an aging roof works that decision through in detail.

Where the streaks come back fastest

Algae discolouration is a warm-and-humid-climate problem, which is why the same roof costs more to keep clean in the Gulf South than in a dry inland metro — not per visit, but per year, because the interval is shorter. Shade compounds it: the elevations that stay wet longest recolonise first, and OSU’s plant pathologist puts the underlying point plainly — “You can clean all you want but to keep moss at bay, the environment needs to change”. Trimming back what overhangs the roof does more for the next three years than the wash itself.

In the humid Deep South that shorter interval is simply the operating reality, and it is worth having a crew who prices a repeat visit sensibly rather than treating each one as a first job — in Louisiana we point readers to the Baton Rouge crew we recommend for flat-rate roof work. If you are elsewhere, the metro list at the foot of this page covers the rest of our coverage area.

How to get a fair quote

Send a couple of photos and ask for a flat price by the job, not an hourly meter. Confirm the crew soft-washes anything delicate. Our estimator turns your size and service into a range before you call, and the per-square-foot guide shows the underlying rates.