Is roof cleaning different on a two-story home?

No roofing document read for this answer treats a two-story home as a different cleaning job. The height rule the trade measures itself against uses feet, and an edge.

OSHA's construction standard, 29 CFR 1926.501(b)(1), says each employee on a walking/working surface “with an unprotected side or edge which is 6 feet (1.8 m) or more above a lower level shall be protected from falling by the use of guardrail systems, safety net systems, or personal fall arrest systems.” The rule is written for construction, and it is quoted here as the benchmark for work at height, not as a finding that a roof cleaning is construction work.

A count of stories is not the unit that rule uses, and the systems it names are defined under fall protection. Who the roofing makers and associations say should be on a roof at all is set out under who should be on the roof, and the warranty.

The chemistry and the pressure instructions belong to the roof material. Eagle Roofing Products' instruction for concrete tile reads the same over one story as over two, and ARMA's procedure for asphalt shingle carries no height at all.

What the height changes is exposure. Eagle's 2019 cleaning article says walking on a roof can be difficult and dangerous and that introducing water only heightens those concerns, and its 2020 article says a contractor walking a steep-sloped roof pitch should use a fall restraint apparatus when cleaning and working on the roof. A ladder set at a second-story eave is a longer climb than one at a single-story eave.

The ways the documents describe for working without standing on a roof, ARMA's ladder and/or walkboards and TRI Alliance's ladder braces, are compared under whether a roof can be cleaned from the ground, and the published conditions for a roof that is walked are under who walks on a roof during a cleaning.

On a two-story home the upper-floor windows sit directly below the roof edge, so a roof wash happens right above that glass.

The National Glass Association's Glass Technical Paper FB01-00 lists “Bleach (or other solutions containing sodium hypochlorite)” among the materials that may cause harm to laminated glass, and says cleaning fluids and their vapors must be kept away from the plastic interlayer exposed around the edge of the pane. Impact windows are built with laminated glass. Keeping a roof solution off that upper row is part of the roof job, not an extra.

What an exterior cleaner has to know about each kind of pane is under the glass types an exterior window cleaner works with, and what a roof rinse leaves on the glass below is answered under whether roof cleaning dirties the windows.

Florida Statutes 489.117(4)(a) lets a local government continue a license it imposed before January 1, 2021 for “rooftop painting, coating, and cleaning above three stories in height,” a clause about local licensing that says nothing about how work at any height is done.

A two-story home sits below that line, and why some rules mention roofs over three stories has its own answer.