A permanent, motorized roof-car or track-mounted platform system — typically the fastest and least disruptive way to access a high-rise façade when the building already has one installed.
A Building Maintenance Unit (BMU) is a purpose-built, motorized platform or gondola permanently installed on the roof of a high-rise. It travels on fixed tracks, a monorail, or davit arms and is lowered and traversed by electric hoists controlled from the platform. Because the structure, power, and fall-arrest systems are all part of the building, technicians step onto a ready-to-use platform rather than rigging temporary ropes or staging each visit.
BMUs are common on Class A office towers, luxury residential high-rises, and hotels built with curtain-wall façades that need regular cleaning and inspection. The system is designed for the specific building geometry, so coverage, reach, and load capacity are engineered into the original installation.
BMU operations follow similar weather thresholds to rope access and swing stage. Most systems are grounded at sustained winds above roughly 30–40 km/h or in electrical storms, and ice on tracks or platform surfaces is a hard stop. Because the platform is motorized and heavier than a rope-access technician, wind can affect control and safety at the upper limits of the system's rated envelope, so operators follow manufacturer-specified limits rather than a single rule of thumb.
BMU work falls under WorkSafeBC OHS Regulation Part 13 (Ladders, Scaffolds and Temporary Work Platforms) and Part 34 (Window Cleaning), with the additional requirement that the permanent system itself be inspected, load-tested, and certified on a regular schedule — typically annually — by a qualified person. Building owners or strata corporations are responsible for maintaining the BMU inspection record; contractors review it before each use and confirm the system is in safe operating condition. Operators must be trained on the specific BMU model and building configuration.
A BMU has the lowest disruption profile of any suspended access method for buildings that have one. There is no daily rigging crew on the sidewalk, no crane or hoist truck to park, and no temporary equipment to store. Disruption is limited to brief roof access for the platform and any standard pedestrian management below the work area.
Choose a BMU whenever the building has a compatible, certified permanent system — it is almost always the most efficient option for that building. Choose swing stage or rope access instead if the BMU is out of service, doesn't reach a specific elevation, or the building has no permanent system at all. Choose a boom lift or water-fed pole for anything within ground-supported reach, since neither needs roof equipment or suspended access.
A Building Maintenance Unit (BMU) is a permanent, motorized platform or gondola system installed on a high-rise roof. It runs on rails, davits, or a roof car and is designed specifically for façade access, window cleaning, and minor maintenance. Unlike temporary rope access or swing stage rigging, the BMU stays with the building.
Most high-rise buildings constructed since the 1990s with curtain-wall façades include some form of permanent façade access system — either a BMU on tracks, a davit arm system, or a monorail. The best way to confirm is to check the roof mechanical plan or the building's maintenance manual. We can also identify it during a site walkthrough.
Usually yes, once the system is certified and the operators are familiar with it. Because the equipment is permanent, setup time is minimal — often just a safety check and power-up. On large, flat elevations a BMU can cover more glass per hour than rope access and avoids the daily rigging time of a temporary swing stage.
The temporary suspended-platform alternative when no BMU exists.
Read more →The versatile suspended method for irregular façades and missing permanent systems.
Read more →The building type most commonly equipped with a BMU.
Read more →Send your BMU inspection record or maintenance manual and we'll confirm compatibility before quoting the work.