Roof Cleaning Cost Calculator

Professional roof cleaning typically runs $0.30 to $0.75 per square foot, so a 2,000 sq ft roof usually costs about $400 to $1,000, with most single-story homes with moderate staining landing around $500 to $800. The price is driven by the roof area, the cleaning method (a low-pressure soft wash is the standard and slightly more than pressure washing), the roof material (metal, tile, and cedar cost more than asphalt shingle), how dirty the roof is (thick moss and heavy black streaks add up to 30%), and your home's height (two stories add about 20%, three-plus about 45% for the harder, riskier access). Prevention extras like zinc strips or an algae-resistant coat and flat add-ons like gutter cleaning add on top. A ~$250 minimum applies to small jobs. Enter your roof above for a localized estimate.

Soft washing uses low pressure plus a specialized cleaning solution (typically a diluted sodium-hypochlorite biocide) to kill and remove algae, moss, mildew, lichen, and the black streaks they cause — the solution does the work, so the roof is rinsed gently rather than blasted. It's the method recommended by asphalt-shingle manufacturers and the Asphalt Roofing Manufacturers Association because high-pressure washing can strip the protective granules off shingles, void the warranty, and shorten the roof's life. Soft washing also keeps the roof cleaner longer because it kills the organisms at the root instead of just knocking off surface growth. For asphalt shingles — the most common roof — soft wash is the safe, standard choice, and it's the default in this calculator.

Yes — on many roofs, high-pressure washing causes real damage, which is why it's used carefully and selectively. On asphalt shingles the force dislodges the granules that protect them from UV and weather, leading to premature aging, leaks, and a voided warranty, and it can drive water up under shingles and tiles. Pressure washing is generally only appropriate for very durable surfaces, and even then with the right technique. If a company proposes pressure washing your shingle roof, treat it as a red flag. The calculator lets you pick the method and prices pressure washing a bit lower, but soft wash is the right call for most homeowners.

Those dark streaks — usually worst on the north- and shade-facing slopes — are most often a blue-green algae (Gloeocapsa magma) that feeds on the limestone filler in asphalt shingles and spreads as black or brown stains. Moss and lichen grow in damp, shaded spots and hold moisture against the roof. Beyond hurting curb appeal, they damage the roof over time: moss lifts and curls shingles and traps water, and algae degrades shingles and reduces their reflectivity, making the home hotter. Overhanging trees, humidity, and shade all speed the growth. Cleaning removes the staining and organisms, and zinc/copper strips or an algae-resistant treatment help keep them from coming back.

Most homes benefit from cleaning every 2 to 5 years, though it depends on your climate and surroundings. Homes in humid, rainy, or heavily shaded areas — or those surrounded by trees — grow algae and moss faster and may need it more often, while dry, sunny climates can go longer. The best approach is to watch for the early signs (black streaks, green moss patches, lichen) and clean before the growth gets thick and starts damaging shingles. A soft wash that kills the organisms, paired with preventive zinc or copper strips, keeps the roof cleaner longer and stretches the time between cleanings. Regular gentle cleaning is far cheaper than the premature roof replacement that unchecked moss and algae can eventually cause.

Cleaning removes the current growth and staining, and a proper soft wash kills the organisms at the root so the roof stays clean longer than simply blasting off surface moss — but no cleaning is permanent, since the spores are airborne and eventually return, especially in damp, shaded spots. Two add-ons slow regrowth: zinc or copper strips along the ridge (rainwater carries trace metal ions down the roof, which inhibit algae and moss) and an algae-resistant protective treatment applied after cleaning. Trimming overhanging branches to let in sunlight and airflow helps too. This calculator includes both the zinc-strip and algae-coat options, so you can price prevention alongside the cleaning.

Roof cleaning is one of the riskier DIY projects and is usually best left to pros. You're working at height on a sloped surface made slick by wet algae and cleaning solution, where a fall can cause serious injury — the leading hazard. Beyond safety, the wrong method or chemicals can damage shingles, kill the landscaping below, or simply not work; pressure washing in particular can ruin a shingle roof. Professionals bring fall protection, the right low-pressure soft-wash gear and solution, the experience to clean without damage, and insurance. A careful homeowner might handle a low, walkable roof, but for steep, tall, or heavily soiled roofs — or anytime you're unsure — hiring an insured pro is the safe choice.

For a typical home it usually takes a few hours — often two to five — depending on roof size, the amount of moss and algae, the method, and access; a single-story asphalt roof with moderate staining is on the quick end, while large, steep, or multi-story roofs with thick moss take longer. With soft washing, some of the cleaning keeps working after the crew leaves: black stains and dead algae can keep fading over the following days to weeks as rain rinses them away, so the roof often looks even better a couple of weeks later. A good crew also spends time wetting down and protecting the plants and landscaping below from the cleaning solution, which is part of a careful, professional job.