Those black streaks running down so many roofs are not dirt. They are mostly algae, and on many shingle roofs they come back year after year until someone kills them. Roof cleaning is one of the better-paying services a wash company can offer, but it is also the one where mistakes cost the most: a fall, a voided shingle warranty, a row of dead shrubs under the drip line. This post covers how roof soft washing works, how to price it, how to keep the crew safe, how to protect the landscaping, and what to tell the homeowner so they know what to expect.
No Pressure on Shingles
Asphalt shingles are covered in granules that protect them from the sun. High pressure knocks those granules off, shortens the life of the roof, and can lift or break shingles. Most shingle manufacturers and roofing industry groups advise against pressure washing roofs, and some warn that it can affect the warranty. Check the manufacturer's guidance on the roofs you clean.
Soft washing avoids the problem. The solution (usually sodium hypochlorite with a surfactant, mixed stronger than a house wash) is applied at low pressure, kills the algae, lichen and moss, and is either rinsed lightly or left to let rain finish the job, depending on the method and the product. Moss and lichen often do not fall off the same day; they die and release over the following weeks. Tell the customer that up front.
Tile, metal and slate roofs each need their own approach. Clay and concrete tile can be fragile to walk on. Metal is slippery and may have a coating to protect. Do not take a roof type you have never cleaned without learning it first.
Safety Comes Before Speed
A roof is the most dangerous place your crew works. Steeper pitches, wet surfaces from the solution and the rinse, and the edge are a combination that injures people. Make fall protection standard on every roof job and learn the safety rules that apply to your crews where you work. A harness, roof anchors and a good ladder setup belong on the truck.
Many crews clean as much as they can from the ground or a ladder at the eave using a long-reach applicator, and only walk the roof when they have to. Low-pitch roofs can sometimes be walked carefully; steep ones should not be walked at all without proper anchoring.
Put roof details in the property notes when you estimate: the pitch, the material, where the ladder can go, power lines nearby, a skylight to avoid, a dog that will be in the backyard. When the crew opens the job in the app, they see those notes before they climb. The note that says "skylight on back slope, hard to see from the ground" can prevent an injury.
Pricing a Roof
Roofs are usually priced by size, adjusted for pitch, height and condition. Size can come from the roof outline on the satellite map; the measure map gives you the footprint area, and you adjust upward for pitch, since a steep roof has much more surface than its footprint. Roofers talk in "squares" (100 square feet of roof), and some wash companies price per square too.
Pitch matters more than size alone. A low-pitch single-story ranch can be cleaned mostly from the edges. A steep two-story roof needs anchors, more setup and slower work. Many companies add a multiplier or a flat surcharge for steep or tall roofs.
Condition matters too. Light streaking takes less solution and time than thick moss on a shaded north slope. As an illustrative example, if your base roof price works out to $350 for an average single-story home, a steep two-story with heavy moss might reasonably be double that. Track the actual time and chemical used on each roof job, and the job costing report will show you whether your multipliers are right. Our pricing post explains how to set the base rates.
Protect the Landscaping and the Gutters
Roof solution runs off the roof, into the gutters, down the downspouts and into whatever is below them. That is where plant damage happens. Wet all the plants around the drip line before you start, keep them wet, and rinse them well afterward. Some crews also bag the downspout outlets or redirect them into a bucket or onto the lawn away from beds, and some use a neutralizer on landscaping.
Watch the timing. A hot, sunny day dries the solution on leaves and makes damage more likely. Early mornings and mild days are kinder to plants.
Gutters will get a dose of the solution and any loosened debris. If the gutters are full, the runoff overflows onto the beds, so many companies clean the gutters first or offer it as an add-on on the estimate. Note in the property notes where each downspout drains and which beds sit under it.
After the job, the photos in the completed alert should include the landscaping as well as the roof. If a shrub browns two weeks later from drought, you want a record that it looked healthy when you left.
Setting Homeowner Expectations
Roof cleaning disappoints customers who expect a pressure-washed look on day one. Streaks may fade over a few days. Moss and lichen often take weeks to release, and some need a rain or two. Old stains from tree sap or rust may not change at all.
Tell the customer exactly that, in writing, on the estimate. "Algae streaks usually fade within days. Moss and lichen die on treatment but may take several weeks to fall away. Some staining may remain." It sounds like a hedge, but it heads off the angry call two days after the job.
Ask about the roof's age and condition. A roof near the end of its life may have bare spots and curling shingles that the cleaning makes more visible. If you see damage, take photos and mention it before you start.
The before and after photos matter more on roofs than anywhere else, because the customer cannot easily see up there. Take before shots from the same angle you will use afterward, and send them in the completed alert when the job is marked done.
When to Offer a Repeat Roof Treatment
A cleaned roof usually stays clean for a few years, depending on shade, trees and climate. That is too long for most homeowners to remember who did it. Make it easy for them.
At the end of the job, offer a check-up or a light re-treatment in a couple of years. Set a recurring service at the interval you recommend (730 days for two years, for example), and the roof comes back up on the Waiting List when it is due, with the notes, photos and mix from the last visit attached. Some companies also offer a yearly roof inspection on homes they house wash, since the crew is already there.
Bundle the roof with the house wash. A homeowner who just watched you clean their roof is the easiest house wash sale you will get, and the reverse is true too. The house washing post covers how the siding side of the job works.
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