Roof Cleaning near you

Black streaking is the common one, and ARMA describes it as algae discoloration, most often attributed to Gloeocapsa magma. It is a surface growth and, left alone, it is mainly a cosmetic and resale issue rather than a structural one. That is worth saying plainly, because roof cleaning is sold hard and some of the urgency is manufactured.

Moss is a different matter. It is a plant with a mat that holds water against the roof, it grows thickest at the laps and in valleys where debris collects, and on shaded roofs in the Pacific Northwest, northern New England and the humid Southeast it keeps surfaces wet long after a roof should have dried. Lichen is more stubborn again, bonding tightly to the granule surface, and even a correct chemical treatment often leaves a shadow where a colony was. Any contractor promising a lichened roof will look new afterward is overselling.

Before paying for a cleaning, it is worth knowing which problem you have and what the roof's remaining life looks like. Cleaning a roof that is near the end of its service life is money spent on the wrong thing, and a roof shedding granules heavily into the gutters is telling you something a cleaning will not fix.

An asphalt shingle is asphalt protected by a layer of mineral granules embedded in its surface. The granules take the ultraviolet punishment so the asphalt does not, and they are not replaceable. ARMA's guidance for anyone cleaning algae from a roof is to avoid scrubbing the surface, as this friction may loosen and remove granules, and not to use a power washer or any type of brush or broom. A pressure wand held at a roof does exactly what ARMA says not to do, faster, and the evidence of it ends up in the gutter as a pile of grit.

Warranty terms are written by individual shingle manufacturers rather than by the industry association, and they differ, so the correct move is to read your own or ask the installer for it in writing before any cleaning is booked. What is consistent is the underlying logic: a manufacturer warrants against manufacturing defects, and damage caused by an improper cleaning method is not one. If a roof is still under a manufacturer's coverage, confirm what that manufacturer permits before a contractor touches it, and keep the written answer with the invoice.

The method ARMA describes is chemical, patient and gentle. A mixture of liquid household bleach, sodium hypochlorite, and water is dispersed gently over the roof rather than driven at it, left to work for at least 15 minutes but no more than 20 minutes, then rinsed gently with water. ARMA warns to apply the solution carefully to avoid damage to other parts of the building and the surrounding landscape, and notes that the application and rinse process will make the roof slippery and potentially hazardous to walk on during treatment. Everything a contractor does well or badly on a roof cleaning follows from those few sentences.

ARMA states that the solution application and rinse process will make the roof slippery and potentially hazardous to walk on during treatment. That is the whole safety brief in one sentence, and it is the reason the best roof cleaning contractors do most of the work from a ladder, a lift, or the ground with extension equipment rather than from the roof plane itself.

Where someone does go up, federal standards apply to their employer. OSHA requires that each employee on a steep roof with unprotected sides and edges 6 feet or more above lower levels be protected from falling by guardrail systems with toeboards, safety net systems, or personal fall arrest systems, and that each employee engaged in residential construction activities 6 feet or more above lower levels be protected by a guardrail system, safety net system or personal fall arrest system unless another provision of the rule provides an alternative measure. Ask the contractor how the crew will be protected and how the anchor point is established, and ask for the certificate of workers' compensation coverage at the same time. A company that intends to send someone onto a wet, chemically treated slope with nothing but rubber-soled shoes is a liability you do not need in your yard.

Cleaning treats the symptom. What returns the roof to streaking is the same set of conditions that produced it: shade, moisture that lingers, and debris that holds both. Trimming branches back to let sun and air onto the roof plane, keeping valleys and gutters clear of leaf litter, and dealing with anything that keeps a slope wet all extend the time between cleanings without a single chemical.

For a longer-term fix, ARMA notes that when considering reroofing, several types of algae-resistant roofing shingles have been developed and are now commercially available, and that these asphalt roofing products are specifically designed to inhibit algae growth for extended periods of time. That is the manufacturer-endorsed route, and it is a decision made at replacement rather than a retrofit. Strips of zinc or copper fastened near the ridge are widely sold on the theory that metal ions carried down the slope by rain suppress growth below them; ARMA's algae guidance does not address them, so treat any promise made about coverage, lifespan or results as the seller's claim and ask for it in writing. Whatever route you take, get the installation details checked against your shingle manufacturer's terms first, since fasteners through a roof are their own risk.

Everything applied to a roof comes off it, and it leaves through your gutters, across your yard and often to the street. ARMA's own guidance is to apply the solution carefully to avoid damage to other parts of the building and the surrounding landscape, which is the first reason to ask how plants, lawn, pond and vegetable beds will be protected and rinsed.

The second reason is public. EPA's NPDES stormwater program regulates discharges from municipal separate storm sewer systems, and municipalities holding those permits implement stormwater management programs describing the practices they use to minimize the discharge of pollutants from the system. Storm drains generally lead to surface water without treatment. A contractor who has thought about this will have a plan for the downspout outlets, for diverting or diluting runoff onto vegetated ground where that is permitted, and for what happens if your downspouts tie into an underground line that discharges at the curb. Ask what the plan is, and ask what your city's stormwater office has to say about it.

Roof cleaning is priced by area, access and risk. What moves a quote is the roof's footprint and pitch, the number of stories and the reach required, whether the crew can work from ladders and the ground or must be on the roof with fall protection, the type of growth and whether heavy moss or lichen needs more than one treatment, the amount of landscaping that has to be protected and rinsed, gutter clearing beforehand, and how the runoff must be managed. A single-story ranch with light streaking and open access is a different job from a steep two-story with mature plantings pressed against every wall.

LokalMatch handles the introduction. You describe the roof once: what it is made of, how many stories, its pitch if you know it, whether the problem is streaking, moss or lichen, and what is planted around the house. Roof cleaning contractors serving your area receive the request and the interested ones reach out to you. Pros pay for the requests they receive, and homeowners are never charged. LokalMatch does not clean roofs, does not set prices, and does not vet, rank or recommend any contractor, so checking insurance and workers' compensation coverage, the method to be used and your shingle manufacturer's position is your part of the job.