Roof Soft-Wash Procedure Standard

Purpose

This standard guarantees a shingle roof gets cleaned with zero mechanical pressure at the surface, the way ARMA and shingle-manufacturer guidance describes it: chemistry does the work, low-volume application delivers it, time does the rest. Skip that discipline and the fastest way to a "cleaner-looking" roof today is a habit pressure-washing trains into a tech without them noticing: closing the fan pattern, dwelling on a stubborn streak, or reaching for a stronger mix to force a result in one pass. Every one of those strips granules, lifts a seal strip, or bleaches shingle color, and none of it shows as damage the day you leave.

The other failure this closes is the opposite one: undertreating out of caution, leaving visible streaking dark and telling the customer "it will fade," when the mix never reached working strength or never got its dwell time. A soft wash done right and one that was skipped look about the same the day you leave. This procedure makes the difference checkable later.

Scope

Covers mixing, application, dwell, and rinse for a sodium hypochlorite (SH) roof wash removing algae (Gloeocapsa magma), moss, and lichen, primarily on asphalt composition shingle. Tile and metal follow the material-specific notes in the roof material compatibility reference before this procedure's mix and dwell bands are applied to them.

Does not cover: protecting landscaping, gutters, and storm drains from the runoff this procedure generates (the roof wash runoff and gutter management standard owns that, and runs alongside this one, not after it), moss-versus-algae technique by material (the algae and moss treatment reference owns that), or what to do when a customer asks for pressure instead (the never-pressure-wash-a-shingle-roof standard owns that).

Roles and the handoff between them

Before you mix or apply anything

Sodium hypochlorite burns skin and eyes on contact and releases chlorine gas if it meets an ammonia-based product, an acid, or certain other cleaners in the tank or on the roof. Wear chemical splash goggles, nitrile or butyl gloves, and a chemical-resistant apron whenever mixing or applying. Never add anything not on the shop's approved roof-mix list, and never top off a tank that held a different chemical without a full rinse and a known-empty check. And if that does not hold, meaning a mix is contaminated or a splash reaches skin or eyes anyway, flush with clean water for at least 15 minutes, remove contaminated clothing, and call poison control or seek medical attention for eye contact or breathing difficulty.

Check the ladder's own duty-rating label before it goes up, not a remembered number. Roof-edge reach work commonly wants an extra-heavy-duty rating, often Type IA or IAA, once the tech's weight, the mix jug, and the wand are counted in, but the label on the specific ladder loaded that day governs, not a shop-wide assumption.

The procedure

1. Confirm the roof material and condition before mixing anything. From a ladder at the eave or the ground with binoculars, identify the shingle type, note lifted tabs, exposed underlayment, or bare mat, and log mounted hardware: skylights, solar panels, dish, vents, exposed fasteners. Acceptance: material and condition logged with a photo per elevation. Wrong looks like assuming shingle from the driveway. Stop rule: metal or tile found where shingle was booked routes to the compatibility reference before the tank is touched, since strength and dwell both change. Hazard: ladder work at the eave; set on level ground, footed or tied off per the shop's ladder standard before anyone climbs.

2. Protect mounted hardware before the mix reaches the roof plane. Cover or bag skylights, solar edges, dish electronics, and any exposed metal the compatibility reference flags SH-sensitive, and count the covers on. Acceptance: a cover count logged, one line per item. Wrong looks like an array covered from memory with a piece left "for later." Stop rule: an item that cannot be adequately covered, most often a vent, gets a plain-water pre- and post-rinse plan instead of a chemical exclusion the mix will find on drift anyway. Hazard: none physical here; the risk is a forgotten cover, which step 8 catches.

3. Mix to the label's roof band and verify it, do not eyeball it. Mix per the label's ratio, then confirm strength with a chlorine test strip rather than trust the ratio alone, since concentrate strength varies by batch and maker. Acceptance: strip reads within the label's roof-application band. Wrong looks like a strip read once and not rechecked after topping off mid-job. Stop rule: an out-of-band reading gets the tank corrected and re-struck before any application, never applied "close enough." Hazard: SH splash and fume exposure while mixing; mix outdoors, upwind, PPE already on, and if the strip will not come into band after two corrections, the batch is dumped per the shop's disposal procedure rather than pushed further.

4. Apply at the softwash skid's low-pressure setting, ridge to eave. Thread on the wide-angle softwash tip, confirmed by color match to the shop's softwash setup rather than the narrow surface-cleaning tip, and work each section ridge-down so gravity carries the solution over the slope. Acceptance: even wetting with no dry gaps, low-pressure delivery held throughout, commonly described in the trade as under 100 psi at the nozzle, well under the 1,500-psi-and-up range a pressure wash runs. Wrong looks like a closed pattern used to "cut through" a dark streak. Stop rule: a tech reaching for a 0- or 15-degree tip, or a surface-cleaner attachment, on a roof stops immediately; that swap is never authorized here. Hazard: SH mist drift in wind; work with wind at your back where pitch allows, stop if drift visibly leaves the roof toward a person, pet, or vehicle.

5. Hold the label's dwell band, watched rather than blind-timed. Start a timer at the band's minimum and watch the surface: a section visibly drying or the foam breaking down before the minimum needs a light re-mist, not a wait past the label's stated maximum. Acceptance: full minimum dwell reached with the surface still wet and active, nothing held past the maximum. Wrong looks like a sun-baked slope drying at half the minimum and left there because "the timer's still running." Stop rule: a drying section gets a light re-mist at the same working strength, never stronger and never a longer single dwell than the label allows. Hazard: continued SH exposure while waiting; stay off the wet surface, PPE stays on.

6. Rinse only as the label calls for it, at the same low pressure, never harder. Where the product is not no-rinse, rinse with the same softwash tip ridge to eave, clearing standing puddles at flat transitions without ever closing the fan to speed it up. Acceptance: no chemical puddling on flat sections, no foam reaching the gutter line in volume. Wrong looks like a narrow tip swapped in because rinsing "was taking too long." Stop rule: a puddle that will not clear at the softwash setting gets more passes at the same pressure, never a higher one. Hazard: the same SH exposure and drift controls from step 4 apply through the rinse.

7. Walk the coverage from the ground and mark anything missed. Check every elevation against the step-1 log, especially valleys, hips, and the shaded side of dormers where reach is worst. Acceptance: full coverage confirmed with no untreated patch larger than a shingle course, or the gap flagged and photographed. Wrong looks like calling it done because the street-facing slope looks good. Stop rule: a genuinely unreachable patch, most often a tight valley behind a chimney, gets noted on the ticket and told to the customer rather than discovered by them. Hazard: none; a ground-level visual check.

8. Remove every cover, count it against step 2, and confirm nothing was left masked. Gloves stay on for this step; a cover's outer surface has been sitting under drift and mist since step 4 and carries the same working-strength SH the roof itself did. Pull tarps and bags by their edges rather than balling them against bare skin, tally against what was logged going on, and give a covered vent or bagged dish a plain-water rinse before uncovering if chemical reached the covering. Acceptance: cover count matches, item for item, zero left in place. Wrong looks like a count skipped because "nothing looked covered from the ground," or gloves stripped off between the rinse step and this one because the wet work is "basically done." Stop rule: a mismatch sends someone back up before the truck leaves, not a callback next week. Hazard: the same ladder-duty check above applies to this return trip, and a cover surface is a contact hazard exactly like the roof plane was, gloves off only after the covers are bagged for disposal or rinse.

The record this produces

• Material and condition log: roof material, pre-existing damage, hardware inventory with cover count on and off.
• Mix verification: test strip reading against the label band, any re-mix event.
• Dwell log: start time, any re-mist event and why, total dwell against the band.
• Coverage check: full or flagged, with photos of any unreachable area.
• Follow-up date: the two-to-six-week contact from the Roles table, set at booking.

One run of this procedure, filled in

Ranch-style home, architectural shingle roof about 12 years old, moderate black streaking across the north slope and a moss patch in a shaded valley behind the chimney.

• Step 1: shingle confirmed at the eave, no lifted tabs or bare mat, one vent and one dish logged, four elevations photographed.
• Step 2: dish bagged, vent covered, two items logged on.
• Step 3: first strip read light, below the label's band. Tank corrected with more concentrate and re-struck; second reading landed in band.
• Step 4: applied ridge to eave with the softwash tip, wind light and at the crew's back, even wetting confirmed on all four elevations.
• Step 5: this step failed on the south-facing gable end. That section sat in direct afternoon sun and began drying about 8 minutes into the label's 10-to-20-minute band. Stop rule taken: a light re-mist at the same working strength was applied to that section only, and its dwell clock restarted from the re-mist rather than pushing the original application past the label's maximum.
• Step 6: rinsed ridge to eave at the softwash setting; the re-misted gable section rinsed last so its dwell matched the rest.
• Step 7: full coverage confirmed on all four elevations; the moss valley behind the chimney photographed separately, since dead-moss removal there follows the algae and moss treatment reference, not this procedure alone.
• Step 8: two covers counted off, vent and dish, matching the two logged on in step 2.

The gable-end re-mist is what makes this run defensible later: the ticket shows a section that dried early was caught and corrected within the label's dwell rules, not stretched past them to save a second trip up the ladder.

References

• ARMA (Asphalt Roofing Manufacturers Association) published guidance on roof algae discoloration and the low-pressure sprayer application method.
• The shingle manufacturer's published cleaning and warranty guidance for the roof on site, since a pressure-based method commonly voids a shingle warranty.
• See related: Roof Wash Runoff and Gutter Management Standard; Roof Material Compatibility for Soft Washing; Never Pressure Wash a Shingle Roof Standard.