Asphalt Shingle Manufacturer Cleaning Guidelines: ARMA Standards Explained

Asphalt shingle manufacturers publish specific cleaning protocols that govern how biological growth — primarily algae, moss, and lichen — may be removed from roofing surfaces without voiding material warranties. The Asphalt Roofing Manufacturers Association (ARMA) has issued consensus guidance that aligns with these manufacturer positions and establishes the baseline standard applied across the professional roof cleaning sector. Understanding how these standards are structured matters for property owners, roofing contractors, and cleaning professionals navigating warranty compliance and material preservation requirements in the US residential and commercial markets. This page describes the scope of ARMA guidance, the mechanisms it addresses, the professional scenarios in which it applies, and the decision points that determine which cleaning approach a given installation requires. For a broader view of how the professional cleaning sector is organized, see the Roof Cleaning Directory Purpose and Scope.

Definition and scope

ARMA — the Asphalt Roofing Manufacturers Association — is the principal US trade body representing manufacturers of asphalt roofing products. ARMA's technical bulletins and best practice documents establish guidance on installation, maintenance, and cleaning that manufacturers routinely incorporate by reference into their warranty terms.

The cleaning guidance specifically addresses the removal of Gloeocapsa magma, the cyanobacterium responsible for the dark black or gray streaking visible on asphalt shingles across humid US climates, as well as moss (Bryophyta species) and lichen (a fungal-algal composite organism). Lichen in particular poses a distinct remediation challenge: its rhizines physically penetrate the granule layer of asphalt shingles, meaning mechanical removal techniques that are appropriate for algae or moss may cause measurable granule loss when applied to lichen-affected surfaces.

The scope of ARMA guidance covers:

Approved chemical agents — specifically low-concentration sodium hypochlorite (bleach) solutions, with or without surfactants, applied at pressures consistent with soft washing protocols
Prohibited mechanical methods — high-pressure washing exceeding 100 psi directly on the shingle surface, wire brushing, and abrasive scrubbing
Application sequencing — pre-wetting of surrounding vegetation, application direction (top-to-bottom), and dwell time allowances
Rinse requirements — low-pressure rinse to remove chemical residue after the specified dwell period

ARMA's guidance does not carry the force of a building code or regulation. It functions as manufacturer-aligned industry consensus, and compliance with it is enforceable only through warranty terms.

How it works

The ARMA-preferred cleaning method is commonly described in the professional sector as soft washing: chemical treatment at low hydraulic pressure (typically under 100 psi at the nozzle) rather than pressure or power washing. The chemical mechanism relies on sodium hypochlorite's oxidizing action to kill biological organisms at the cellular level, after which the dead organic material is rinsed away or weathers off naturally over subsequent rain events.

Sodium hypochlorite solutions used in professional roof cleaning typically range from 1% to 3% active chlorine concentration at the surface, diluted from higher-concentration stock solutions. ARMA guidance does not specify a precise concentration floor or ceiling in its publicly available bulletins, but it consistently endorses bleach-based treatment as the approved method and consistently prohibits high-pressure washing as a primary cleaning technique.

The distinction between pressure washing and soft washing is critical under ARMA standards. Pressure washing — conventionally defined as water delivered at 1,500 psi or above — can strip granules from asphalt shingles, accelerate mat deterioration, and void manufacturer warranties. Soft washing, by contrast, relies on chemical dwell time rather than hydraulic force to achieve biological kill. This contrast appears directly in ARMA's publicly available technical guidance and is reflected in the cleaning specifications included with major manufacturer warranty documentation from producers such as GAF, Owens Corning, and CertainTeed.

For a listing of cleaning professionals who operate within these technical parameters, the Roof Cleaning Listings section provides geographic access to vetted service providers.

Common scenarios

The ARMA cleaning standard applies across a defined set of field conditions:

Algae streaking on 3-tab and architectural shingles — the most common scenario; soft-wash treatment with sodium hypochlorite is the standard approach and the one most directly addressed in ARMA documentation
Moss accumulation on north-facing or shaded roof sections — moss retains moisture against the shingle surface, accelerating mat degradation; removal requires chemical kill followed by low-pressure rinse, with physical debris brushed off only after the moss is dead and brittle
Lichen colonies on aging shingles — the highest-risk scenario under ARMA guidance; lichen rhizines embedded in the granule layer mean that even dead lichen may leave physical damage upon removal, and ARMA guidance acknowledges that full eradication of lichen staining in a single treatment cycle may not be achievable without granule loss
Pre-sale or pre-inspection cleaning — property transactions frequently trigger cleaning requests; contractors must confirm whether shingles are within their rated service life before treating, as cleaning a shingle set in advanced granule-loss stage may accelerate deterioration rather than reverse it

Decision boundaries

The ARMA standard creates structured decision points that determine which cleaning approach applies and whether cleaning is appropriate at all.

Chemical vs. mechanical removal: ARMA endorses chemical treatment and prohibits high-pressure mechanical removal as a standalone method. Any hybrid approach — chemical pre-treatment followed by low-pressure rinsing — must maintain pressure below manufacturer thresholds.

Warranty-active vs. warranty-expired shingles: ARMA guidance is explicitly intended to preserve warranty coverage. On shingles past their rated service life or on installations where the warranty has already been voided by prior improper maintenance, ARMA guidance remains the best-practice benchmark but does not carry warranty implications.

Algae vs. lichen treatment protocols: Algae treatment and lichen treatment are not interchangeable. Algae responds fully to a single chemical treatment cycle; lichen may require extended dwell periods or repeated applications, and the granule condition of the shingle must be assessed before any treatment proceeds.

Contractor qualification: ARMA does not operate a contractor certification program. Qualification assessment falls to individual manufacturers' approved contractor networks and, where applicable, to state contractor licensing boards that regulate roofing or exterior cleaning work. Licensing thresholds vary by state; 22 states require a specialty contractor license for exterior cleaning work involving chemical application on residential structures (structure of licensing requirements described by the National Conference of State Legislatures). Additional context on how professionals navigate these qualification standards is available through the How to Use This Roof Cleaning Resource section.

Safety classifications under chemical handling regulations: Sodium hypochlorite solutions used in professional concentrations (10%–12.5% stock) are regulated under OSHA's Hazard Communication Standard (29 CFR 1910.1200), which requires Safety Data Sheets, proper labeling, and employee training. Environmental runoff from roof cleaning chemicals may also be subject to stormwater management requirements under the EPA's National Pollutant Discharge Elimination System (NPDES) program (40 CFR Part 122).

References

✅ Citations verified Feb 25, 2026 · View update log