A Building Maintenance Unit (BMU) is a permanent, roof-mounted powered platform built into a completed high-rise for ongoing facade access -- window washing, glazing inspection, cleaning. Unlike a temporary suspended scaffold that comes down when a project wraps, a BMU stays on the building for its service life, which means the inspection and certification obligations don't end at commissioning -- they're ongoing.
What Governs BMU Inspection
BMUs and other permanent powered platforms for building maintenance fall under OSHA 29 CFR 1910.66, the federal standard for powered platforms, and the referenced safety standard ANSI/ASSE A120.1, which sets design, inspection, testing, operation, and maintenance requirements for the equipment. This is separate from the NYC Building Code Chapter 33 rules that govern temporary suspended scaffolds and sidewalk sheds used during active construction or restoration work.
The Inspection Cadence
- Annual inspection — OSHA 1910.66 requires the building's supporting structure and the powered platform equipment be inspected at intervals not exceeding 12 months, typically by a competent person or licensed engineer/specialist.
- Pre-use / periodic checks — operators are expected to perform visual and operational checks before use and on a regular schedule set by the equipment's own maintenance program, in addition to the annual inspection.
- Certification records — the building owner is responsible for keeping documented certification records (date, inspector, equipment identifier) on file, not just completing the inspection itself.
Why the Structural Design Matters Too
A BMU's supporting structure isn't an afterthought bolted to the roof — the structural elements carrying the hoist and platform loads have to be designed by a registered/licensed professional engineer, sized well above the equipment's rated or stall load per NYC Building Code structural requirements. That structural design is what an annual inspection is actually checking against: has anything shifted, corroded, or degraded relative to what the engineer originally specified.
Don't Confuse BMU Rules With Temporary Scaffold Rules
This is a common point of confusion for building owners and property managers: a BMU permanently mounted on a completed building is a different regulatory animal than the swing stage or suspended scaffold rig brought in for a facade restoration project under FISP/Local Law 11. The temporary rig follows Building Code Chapter 33 (installation, pre-shift inspection, permits, engineered rigging plans specific to that job). The BMU follows OSHA 1910.66/ANSI A120.1 and stays governed by that standard for as long as it's on the roof. Knowing which regime applies to which piece of equipment on your building avoids missing an obligation that falls under the "other" set of rules.
Where This Fits With Your Access Plan
If your building has a BMU on the roof, that's a separate, ongoing maintenance-equipment relationship from any temporary access work you bring in for a restoration project. When we scope monorail scaffolding or suspended-scaffold access for facade work on a building that also has a BMU, we coordinate around what's already installed rather than treating it as a blank roof — tell us what's up there and we'll plan the temporary rig accordingly.