Rex says
Money math without the spreadsheet headache. Plug in your numbers and I'll show you exactly where the dollars land.
Try a scenario
Click to load — tweak from there.Inputs
Result
Total roof cleaning cost
$600
Effective cost per sq ft
$0.30
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How to use this
- 1Enter roof area (sq ft).
- 2Enter base soft wash rate ($/sq ft).
- 3Enter roof pitch.
- 4Enter algae/moss staining level.
- 5Read your total roof cleaning cost on the right — it updates as you type.
- 6Hit Share to keep the scenario or send it to someone.
About this calculator
Roof cleaning — typically a low-pressure soft wash with a cleaning solution to kill algae, moss, and lichen — is priced per square foot of roof area, adjusted for roof pitch (steeper roofs need more safety gear and time) and staining severity. 2026 US national averages run roughly $0.20-$0.45 per sq ft for a standard soft wash on a moderate-pitch asphalt shingle roof, with steep or multi-story roofs and heavy black algae staining pushing toward $0.50-$0.75 per sq ft. Pressure washing is generally not recommended for asphalt shingles since it can strip granules and void manufacturer warranties, so most reputable roof cleaners use the soft-wash method by default. This calculator applies pitch and staining multipliers to a base rate so you can compare quotes; roof cleaning every 2-4 years in humid, shaded climates prone to algae growth is typical, while drier climates may go longer between cleanings.
Worked example
Using the values the calculator loads with:
Inputs
- Roof area: 2000 sq ft
- Base soft wash rate: 0.3 $/sq ft
- Roof pitch: Low/moderate pitch
- Algae/moss staining level: Light
Results
- Total roof cleaning cost: $600
- Effective cost per sq ft: $0.30
What each field means
Inputs
- Roof area (sq ft)
- The roof area used in the calculation, measured in sq ft. Starts at 2000 sq ft so you have a working example on load. Accepted range: 500–6000 sq ft.
- Base soft wash rate ($/sq ft)
- The base soft wash rate used in the calculation, measured in $/sq ft. Starts at 0.3 $/sq ft so you have a working example on load. Accepted range: 0.15–0.8 $/sq ft.
- Roof pitch
- Pick the option that matches your situation — the maths changes per option. Choices: Low/moderate pitch, Steep pitch, Very steep / multi-story.
- Algae/moss staining level
- Pick the option that matches your situation — the maths changes per option. Choices: Light, Moderate, Heavy.
Results
- Total roof cleaning cost
- Returned as a money amount in US dollars and shown as the headline result. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Effective cost per sq ft
- Returned as a money amount in US dollars. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
FAQ
Is pressure washing safe for my roof?
For asphalt shingles, no — high-pressure washing can strip protective granules and void the shingle manufacturer's warranty. Reputable companies use a low-pressure soft wash with an algaecide solution instead, which is safer and often more effective long-term.
What causes those black streaks on my roof?
Black streaking is typically caused by Gloeocapsa magma, a algae that feeds on the limestone filler in asphalt shingles; it thrives in humid, shaded conditions and spreads over time if untreated, which is why northern and shaded roof slopes often stain first.
How often should a roof be cleaned?
Every 2-4 years is typical in humid or shaded climates prone to algae and moss; drier climates with more sun exposure may only need cleaning every 5+ years or when visible staining appears.
Do zinc or copper strips reduce future cleanings?
Yes — zinc or copper ridge strips release ions when it rains that inhibit algae regrowth, and many roof cleaners recommend installing them after a cleaning to extend the interval before the next service is needed.
Accuracy and limitations
- Results are estimates before tax, fees, and inflation unless an input explicitly covers them.
- Rates are treated as fixed for the whole period — variable-rate products will drift from this projection.
- This is educational maths, not financial advice. Check anything contractual with the lender or your accountant.
Related tools
Cite this calculator
Writing about this topic? Grab a citation — every link helps keep these tools free.
RevenueLab. (2026). Roof Cleaning Cost Calculator. Retrieved from https://www.revenuelab.fyi/toolbox/roof-cleaning-cost
<p>Source: <a href="https://www.revenuelab.fyi/toolbox/roof-cleaning-cost" target="_blank" rel="noopener">Roof Cleaning Cost Calculator — RevenueLab</a> (2026).</p>
Source: [Roof Cleaning Cost Calculator — RevenueLab](https://www.revenuelab.fyi/toolbox/roof-cleaning-cost) (2026).