Pro edition
Surface Guide
The reference a crew actually works from. Every row includes what failure looks like, because that is the part experience teaches and a price list does not.
PSI and nozzle by surface
| Surface | PSI | Nozzle | Distance | What failure looks like |
|---|---|---|---|---|
| Concrete driveway, unsealed | 3,000 | 25° or surface cleaner | 6–12 in | Wand marks — permanent stripes where the tip lingered. |
| Concrete, sealed | 1,500 | 40° | 12–18 in | Sealer stripped in patches; the whole slab then needs resealing. |
| Brick, modern mortar | 2,500 | 25° | 12 in | Mortar erosion at the joints, worst on the wettest wall. |
| Brick, lime mortar (pre-1930) | 800 or soft wash | 40° | 18 in+ | Joints blown out in seconds. Repointing is the repair. |
| Composite decking | 1,200–1,500 | 40°, fan, moving | 12 in | Cap-layer scarring that holds dirt permanently. |
| Vinyl siding | Under 500 | Soft wash / X-jet | Flood, do not blast | Water driven behind panels into sheathing. Invisible until it is expensive. |
| Painted wood, cedar | Under 500 | Soft wash | Flood | Raised grain, furring, and paint driven off at the edges. |
| Stucco / EIFS | Under 500 | Soft wash | Flood | Punch-through on EIFS. One of the costliest repairs in the trade. |
| Asphalt shingle roof | None | Soft wash only | Flood, downward | Granule loss, water under the courses, warranty voided. |
Soft wash, in order
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Pre-wet everything
Surface and all surrounding planting. A dry surface absorbs solution unevenly and a dry plant absorbs it entirely.
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Apply low and work up
Bottom to top on a vertical surface, so runs do not streak into dry areas.
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Dwell 5–10 minutes
Long enough to kill, short enough not to dry. Never let solution dry on a surface — that is what causes streaking, not the solution itself.
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Re-wet if it is drying
On a hot wall in direct sun, mist again rather than pushing on.
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Rinse top down, low pressure
Gravity does the work. Rinse until the runoff is clear, then once more.
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Rinse the plants again
Twice. The second rinse is the one people skip and the one that saves the shrubs.
Plant protection
- Pre-wet every plant inside the splash radius, not just the ones directly below
- Tarp anything precious, and weight the tarp — wind lifts it exactly when you stop watching
- Never mix solution stronger than the label because the growth is stubborn; use dwell time instead
- Rinse plants during the job as well as after, if it takes more than about twenty minutes
- Downspouts route to somewhere — know where before you start, especially near a pond
Cold weather
- How cold is too cold?
- Below about 40°F the sodium hypochlorite loses effectiveness and anything you rinse can freeze on a walkway. That is both a bad clean and a liability.
- What about the machine?
- Drain the pump and lines or use pump antifreeze. A cracked pump head is a several-hundred-dollar lesson that everyone in this trade learns exactly once.
- Is winter a bad time to book?
- It is a good time to book and a bad time to schedule. Quote in winter, clean in spring, and get the early slot before the algae returns.