Surface PSI and nozzle chart
Every surface has one pressure that cleans it and one that ruins it, and the gap between them is smaller than most people believe. This table is the site's single source for that number: eighteen surfaces, the working pressure band, the tip, and what the chemistry has to do that the pressure cannot.
Safe pressure by surface
| Surface | Working PSI | Nozzle | Detergent |
|---|---|---|---|
| Poured concrete drivewayFlatwork | 3000-3500 | 25 deg Green / 20 in surface cleaner | Degreaser pre-treat, dilute SH post-treat |
| Concrete sidewalk and stepsFlatwork | 2500-3200 | 25 deg Green | SH post-treat |
| Stamped or decorative concreteFlatworkSealed surface — pressure hazes and strips the colour coat. | 1200-2000 | 40 deg White | Neutral cleaner |
| Concrete paversFlatworkEmpties joint sand; plan to re-sand. | 1500-2500 | 25 deg Green | Efflorescence remover if blooming |
| Asphalt drivewayFlatworkPressure lifts the binder and exposes aggregate. | 1200-2000 | 40 deg White | Neutral cleaner |
| Garage floor with oilFlatwork | 3000-3500 | 15 deg Yellow then green | Alkaline degreaser, long dwell |
| Vinyl sidingVerticalPressure drives water behind the courses. | 100-500 (soft wash) | ~65 deg Black soap, white rinse | 0.5-1.5% SH + surfactant |
| Fibre-cement sidingVertical | 100-500 (soft wash) | ~65 deg Black soap, white rinse | 0.5-1.5% SH + surfactant |
| Painted wood sidingVerticalTest for chalking first — chalked paint is a paint job. | 100-400 (soft wash) | ~65 deg Black soap, white rinse | Mild detergent |
| Stucco and EIFSVerticalEIFS is foam behind a skin. Pressure punches through. | 100-800 (soft wash) | 40 deg White | Low-strength SH |
| Brick and mortarVerticalSoft or historic brick spalls. Test patch, always. | 1200-2000 | 25 deg Green | Masonry cleaner, pre-wet |
| Natural stoneVerticalAcid etches limestone and marble permanently. | 800-1500 | 40 deg White | pH-neutral stone cleaner |
| Cedar and softwood deckingWoodFurs at pressure. Work with the grain, tip well back. | 500-1200 | 40 deg White | Sodium percarbonate, neutralising rinse |
| Pressure-treated deckWood | 600-1200 | 40 deg White | Percarbonate cleaner |
| Composite deckingWoodExceeding the maker's figure voids the warranty and hazes the boards. | Manufacturer max, often <=1500 | 40 deg White | Approved cleaner only |
| Wood fenceWood | 500-1200 | 40 deg White | Percarbonate cleaner |
| Asphalt shingle roofRoof & gutterARMA: do not use a power washer, brush or broom on shingles. | Soft wash only | ~65 deg Low-pressure soft-wash tip | ~3% SH, 15-20 min dwell |
| Aluminium gutter faceRoof & gutterOxidation stripes are chemical, not pressure. Pressure dents the trough. | Under 500 | 40 deg White | Gutter-brightening surfactant, brushed |
Showing 18 of 18 surfaces. Every colour dot is named in text beside it — the colour is data here, not decoration.
18 surfaces
PSI & nozzle quick reference
- 0 degRed
- Spot jet. Etches most surfaces.4000 PSI
- 15 degYellow
- Stripping bare concrete.4000 PSI
- 25 degGreen
- General concrete and walkways.3500 PSI
- 40 degWhite
- Siding, wood, vehicles.1500 PSI
- ~65 degBlack
- Detergent draw, low pressure.500 PSI
How to read a band
Start at the bottom of the band and work up only if the surface is not coming clean. Most damage happens because someone started at the top. Distance matters as much as the dial: the same 3,000 PSI at six inches and at eighteen inches are two different tools.
Surface damage risk
Soft wash means low pressure, not a wider tip at full pressure. Anything on this table listed as soft wash — siding, stucco, shingles — is a job for chemistry and dwell. Fitting a 40-degree tip and leaving the machine at 3,000 PSI is still a pressure job and will still do the damage.
The three surfaces people get wrong
- Stamped concrete. It looks like concrete and behaves like a coating. The colour lives in a thin surface layer that pressure hazes and strips.
- EIFS. Synthetic stucco is foam behind a thin skin. Enough pressure to clean ordinary stucco will punch a hole you cannot see until it rains.
- Composite decking. The manufacturer publishes a maximum. That figure, not the deck's apparent toughness, is what governs — and exceeding it voids the warranty.