Don’t pressure wash an asphalt shingle roof. The Asphalt Roofing Manufacturers Association (ARMA) warns it causes granule loss and very likely premature roof failure. Clean shingles with a bleach-and-water spray and a garden-hose rinse instead. Pressure washing is acceptable on concrete tile at low pressure: concrete tile maker Eagle Roofing says to use water only and never exceed 1,200 PSI. Clay tile and metal roofs need even gentler treatment, so check the manufacturer’s limits first.
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Can you pressure wash your roof? It depends on the material
| Roof type | Pressure washer? | What to use instead or within | Source |
|---|---|---|---|
| Asphalt shingles (3-tab or architectural) | No | 1:1 bleach and water, 15 to 20 minutes, rinse at hose pressure | ARMA |
| Concrete tile | Yes, low pressure | Water only, never above 1,200 PSI; hire a tile-experienced contractor | Eagle Roofing |
| Clay tile | Avoid | Soft wash; some tile makers advise against pressure washers entirely | Monier |
| Stone-coated metal | Avoid high pressure | Gentle rinse, under 500 PSI, with a roof-safe cleaner | DECRA |
| Painted metal panels | Only at low pressure | Mild detergent and a hose; follow the panel maker’s limits | Panel manufacturer |
| Cedar shake | No | Oxygen bleach or a wood roof cleaner, low-pressure rinse | Shake installer |
| Slate | No | Quat cleaner; never walk on slate | Slate specialist |
Asphalt shingles cover most American homes, so for most homeowners, pressure washing is the wrong way to clean a roof.
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See local roof cleaning prices →Why pressure washing damages roofs
- Shingles lose granules. The mineral granules on asphalt shingles block UV. A pressure washer blasts them off, and the exposed asphalt ages faster. ARMA puts it plainly: never use a pressure washer to clean an asphalt shingle roof.
- Water goes where it shouldn’t. High-pressure spray forces water under tile laps, metal seams and flashing, which can cause leaks you won’t trace back to the cleaning.
- Finishes wear off. Concrete tiles have a factory surface coating and clay tiles a fired finish. Too much pressure erodes them, and metal coatings can lift or scratch.
- Growth comes back. Pressure knocks off visible moss and algae without killing what remains in the surface. Chemical treatment kills it.
Equipment for low-pressure roof cleaning
| Item | Why you need it |
|---|---|
| Pressure washer nozzle set | The 40-degree (white) tip spreads the spray; never use the 0-degree (red) or 15-degree (yellow) tips on a roof |
| Telescoping extension wand | Lets you rinse from a ladder or the ground instead of standing on a wet roof |
| Bleach-rated pump sprayer | Applies cleaning solution before rinsing, without pressure |
| Wet & Forget hose-end sprayer | A no-rinse treatment you can spray from the ground, for shingles |
| Roof safety harness kit | Required if you step onto the roof; see our roof harness guide |
How to clean asphalt shingles without a pressure washer
This is ARMA’s method in short. Our bleach cleaning guide covers it in detail.
- Soak plants below the roof with water and cover delicate ones.
- Mix household bleach and cold water 1:1 in a bleach-rated sprayer.
- Spray the streaked or mossy areas from a ladder.
- Leave it 15 to 20 minutes without letting it dry.
- Rinse with a garden hose at normal pressure, then flush the plants again.
- Let the next few rains finish washing away dead growth. Repeat rather than scrub.
Prefer to skip bleach? Spray-and-leave quat cleaners such as Wet & Forget kill growth and let rain clear it over weeks to months.
How to pressure wash a concrete tile roof
Concrete tile is the one common roof material where light pressure washing is normal maintenance. The Tile Roofing Industry Alliance notes it is common practice but that wet tile roofs are slippery, so the work should be done by a qualified professional (TRI). If you do it yourself:
- Treat growth first. Pre-spray moss and algae with a quat cleaner or diluted bleach and let it work, so you need less pressure.
- Set the pressure low. Eagle Roofing recommends water only, never above 1,200 PSI. Use the 40-degree tip.
- Stay off the tiles where you can. Work from a ladder with a standoff, or use a roof ladder or crawl board that spreads your weight. Concrete tiles crack when stepped on in the wrong place.
- Spray down the slope only. Work from the ridge toward the eaves, holding the tip 12 to 18 inches from the surface. Never aim up under the tile laps.
- Rinse gutters and downspouts afterward to clear the grit and debris you washed off.
Clay tile is more brittle and its fired finish is easy to damage. Several tile manufacturers advise against pressure washing clay or concrete tile at all, so check yours and lean toward a soft wash.
How to clean a metal roof
Metal roof limits vary by coating, so the panel manufacturer’s instructions come first. DECRA, which makes stone-coated metal roofing, says not to exceed 500 PSI and to rinse gently with a roof-safe cleaner (DECRA).
- Rinse loose dirt off with a garden hose.
- Apply a mild detergent or a metal-roof cleaner approved for your coating, and let it sit a few minutes.
- Rinse from the ridge down, spraying along the seams rather than across them, and never directly at exposed fasteners.
- Check painted finishes with your panel maker before using chlorine bleach.
Safety rules for any roof cleaning
- Start dry, stay off wet surfaces. Cleaning makes roofs slippery. Work from a ladder at the eaves wherever you can.
- Use a harness and roof anchor if you step onto the roof at all, and never work alone.
- Respect the wand. Pressure washer spray can cut skin. Never point it at anyone, and shut the machine off before changing tips.
- Hire out the high or steep jobs. Two-story roofs, steep pitches and tile you can’t walk on safely are professional work. Our DIY vs pro quiz helps you decide.
What professional roof cleaning costs
Professional roof cleaning averages around $460 nationally, with two-story, steep and tile roofs at the higher end. Prices by state and roof size are in our roof cleaning cost guide. When you get quotes, ask what pressure the crew uses on your roof type. A company that plans to pressure wash shingles is a company to skip.
Roof pressure washing FAQs
Can you pressure wash asphalt shingles on a low setting?
ARMA’s guidance has no low-pressure exception: never use a pressure washer on an asphalt shingle roof. Rinse with a garden hose at normal pressure after a bleach-and-water treatment.
What PSI is safe for a tile roof?
For concrete tile, Eagle Roofing recommends water only and never more than 1,200 PSI. For clay tile, many manufacturers advise soft washing instead. Always check your tile maker’s guidance.
Can pressure washing void my roof warranty?
It can. ARMA says other cleaning methods should not be used on shingles without the manufacturer’s approval, and damage from pressure washing is not a defect the warranty covers. Read your warranty’s maintenance section before cleaning.
Is soft washing the same as pressure washing on a low setting?
No. Soft washing relies on a cleaning solution, usually diluted sodium hypochlorite with a surfactant, to kill growth, followed by a low-pressure rinse. See our roof soft washing guide.
Can you pressure wash an RV rubber roof?
Better not to. Use a soft brush and a cleaner made for EPDM or TPO roofs; high pressure can lift seams and the sealant around vents.
Related guides
- Roof soft washing: chemicals and equipment
- How to clean roof shingles with bleach
- Removing black algae streaks
- How to clean roof tiles
- How often to clean your roof
- Roof cleaning cost guide
Updated November 2026. Sources: ARMA, Algae & Moss Prevention and Cleaning for Asphalt Roofing Systems; Eagle Roofing, How to properly clean your concrete tile roof; Tile Roofing Industry Alliance; DECRA metal roof cleaning tips; Monier roof tile cleaning advice.
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