Roof Cleaning Chemicals

Those black streaks on asphalt shingles are algae, and no amount of water pressure removes them without tearing up the roof. The right roof cleaning chemicals do the work at garden-hose pressure. We keep 12.5% sodium hypochlorite, surfactants, and neutralizers on the shelf in Gaithersburg for soft wash crews across Maryland. First roof job coming up? Call 301-519-9274 and we will talk you through the mix.

Building a Roof Cleaning Mix That Works

Every professional roof wash starts with the same three ingredients. Sodium hypochlorite kills the growth. A surfactant makes the mix cling to a sloped surface long enough to work. A scent additive covers the chlorine smell while you are on a customer's property. The strength matters more than the brand. Household bleach runs 5 to 6 percent and is too weak to be worth hauling up a ladder. Pro crews start with 12.5% SH and cut it down to roughly a 2 to 3 percent solution at the roof surface. Siding takes closer to 1 percent, which is why a roof mix should never go straight onto a house wash job.

Get the gallons right the first time. Our free SH Mix Calculator turns your real bleach strength, target percentage, and tank size into gallons of SH, gallons of water, and surfactant ounces, with presets for roofs, siding, and concrete.

Why the Surfactant Earns Its Keep

Straight SH runs off a 6/12 pitch before it can kill anything, and every gallon that runs off is money in the gutter. A surfactant like Roof Dancer or Stick-It Foamer breaks the surface tension so the mix sheets out and hangs on through the 15 to 30 minute dwell the growth needs. You use less chemical per square, the kill is more even, and you make fewer passes. A few ounces per batch is the cheapest efficiency upgrade in soft washing.

Protecting Landscaping and Gutters

Most roof cleaning complaints are not about the roof. They are about dead boxwoods under the downspouts. Pre-wet every plant in the runoff path, keep a helper rinsing while you spray, and rinse again when you finish. For the runoff itself, slide a 4 mil poly tube sleeve over the downspout and route the discharge to a bucket or a safe drain instead of the flower bed. If overspray or runoff still finds a plant, Bleach Arrest neutralizes SH on contact and has saved more than one landscaping bill. Budget for it on every roof quote.

What to Put in the Truck

SH pricing is per gallon and we fill fresh. Bring your carboys or grab ours.

From the Field

The mistake we see most is not the mix, it is the age of the SH. Sodium hypochlorite loses strength every week it sits, and heat speeds that up badly. A drum that spent July in a box truck might test at half its label strength by August, and then the crew blames the surfactant when streaks stay behind. Buy SH in quantities you will burn through in a few weeks and store it cool and shaded. Second lesson from the counter: crews that skip the downspout sleeves end up paying for shrubs. An $8 roll of poly tube is the cheapest insurance this trade offers. And keep real PPE on the roof, chemical-rated gloves, goggles, and a respirator when the wind kicks up. SH mist is nothing to breathe all day.

Related Collections

• SH Mix Calculator: soft washing solutions by surface
• Soft wash equipment and 12 volt soft wash pumps
• House washing chemicals
• All cleaning chemicals and chemical additives
• Deck and wood cleaners
• Concrete cleaning chemicals
• X-Jet chemical applicators and chemical injectors
• Pump up sprayers and chemical handling

Soft wash crews around Montgomery County refill SH at our Gaithersburg store all season.

Frequently Asked Questions

What ratio of sodium hypochlorite cleans a shingle roof?

Most contractors land around a 2 to 3 percent SH solution at the surface, which works out to roughly one part 12.5% SH to three or four parts water plus surfactant. Heavy moss or lichen may take a hotter mix and a second application.

Why do the black streaks keep coming back?

The streaks are a hardy algae called Gloeocapsa magma that feeds on the limestone filler in shingles. A proper soft wash kills it, but spores travel on the wind, so expect a cleaned roof to stay clean for several years rather than forever.

Can I skip the surfactant and just spray bleach?

You can, but the mix will run off the slope before the dwell time is up. You will use more chemical, get patchy results, and dump more runoff into the landscaping. Surfactant costs pennies per gallon of mix.

Will roof cleaning chemicals kill my plants?

SH will burn foliage it sits on. Pre-wet the plants, rinse during and after the job, capture downspout discharge with poly sleeves, and keep a neutralizer like Bleach Arrest mixed and ready. Handled that way, plant damage is rare.

Why not just pressure wash the shingles?

High pressure strips the granules that protect the shingle and can void the roof warranty. Shingle manufacturers point to chemical cleaning at low pressure instead. If a method needs more pressure than a garden hose to rinse, it does not belong on an asphalt roof.

How long should the mix sit before rinsing?

Give it 15 to 30 minutes. The growth usually browns out as it dies. On a hot day, mist the surface so the mix never dries completely, since dried chemical stops working.

How should I store sodium hypochlorite?

Cool, shaded, and sealed, and buy only what you will use within a few weeks. SH loses strength as it ages and heat makes it worse. Weak SH is the hidden cause of most callback jobs.