Building Maintenance Units (BMU)

Building maintenance units and façade access equipment are the permanent systems used to reach the outside of a building for cleaning, inspection and repair. They are lifting equipment that carries people at height, so their condition is set by statutory inspection and certification as much as by wear, and a failed or uncertified system stops façade maintenance altogether.

The system must reach every part of the façade that needs maintenance. A building's façade access strategy sets which equipment serves which elevation. Façade changes over time, such as new canopies, louvres, signs or balconies, can leave elevations that the equipment can no longer reach.

What shortens life:

• Infrequent use: equipment used once or twice a year seizes, corrodes and is neglected between uses.
• Coastal and rooftop exposure: salt, UV and water on equipment stored uncovered on the roof.
• Water in davit sockets and track fixings, which corrodes the base and leaks through the roof membrane.
• Lapsed maintenance contracts and lapsed certification.
• Obsolete controls, which turn a minor fault into a long outage.

Structural fatigue and corrosion

The jib, carriage and slewing assembly carry cyclic loads at high stress points. Fatigue cracks start at welds and section changes; corrosion reduces section at connections and fixings. Track and rail fixings corrode where water collects, and where they penetrate the roof, they leak.

Stability

Roof-mounted units rely on counterweight and rail clamps to stay on the roof under load and wind. Altered counterweights, worn clamps or modified units have led to instability incidents; regulators in Australia have issued safety alerts on BMU stability.

Wire rope deterioration

Ropes lose strength through broken wires, corrosion, abrasion and kinking. They are discarded against defined criteria; a rope that is not inspected to those criteria can fail.

Hoist, brake and drive wear

Hoist brakes, gearboxes and drives wear with use and seize without it. Brake failure on a hoist carrying people is the critical mechanical failure.

Control obsolescence and water

Controls, limit switches and safety devices age, take in water and become unsupported. Parts become unavailable and the unit stays out of service while controls are re-engineered.

Anchor and socket corrosion

Davit sockets fill with water and corrode from the inside. Rope access anchors corrode at their base, and roof works that disturb the membrane around them can compromise their fixing. Anchors that are not inspected and recertified on schedule cannot be relied on.

Loss of coverage

Façade alterations and new rooftop plant can block reach or travel, leaving elevations that can only be reached by hired equipment.

From aerial imagery and the roof

• Equipment present: track, carriage, monorail, davits, anchors; covered or uncovered.
• Corrosion on the unit, track and fixings; ponding around track fixings and sockets.
• Rooftop plant or structures in the travel path of the unit.

On site

• Inspection tags and the logbook: current, overdue or missing.
• Rust at welds, connections and the slewing ring; oil leaks from hoists and gearboxes.
• Wire ropes with broken wires, corrosion or kinks.
• Controls cabinet condition, water ingress, labels and warning signs.
• Davit sockets full of water or debris; anchors loose or corroded.
• Façade restraint points present and usable.

In the records

• Periodic and major inspection reports, with outstanding defects.
• Plant registration, design registration and load test records.
• Maintenance contract and service reports; unit out of service for extended periods.
• Façade access strategy and whether it still covers every elevation.
• Anchor certification with dates; rescue plans.

BMU problems are diagnosed more from records than from sight. The question is less "what is wrong" than "can this equipment be used, and for how long".

Findings are graded by what they demand: safety (can hurt someone now), failure (failed and damaging the building), condition (distress present and progressing), lifecycle (renewal due on age and exposure), deadline (a regulator or ordinance sets the date), check (investigate before sizing works) and nil (cosmetic or stable).

A competent person, usually the maintenance contractor or an independent lifting equipment inspector, carries out periodic and major inspections. A façade access consultant assesses coverage and strategy.

• Records review: logbook, inspection reports, registrations, load tests, maintenance reports.
• Periodic inspection of the structure, mechanisms, ropes, brakes, controls and safety devices at the statutory interval.
• Major inspection: strip-down and non-destructive testing of welds, slewing ring and highly stressed components, with load testing, at the interval set by the standard or the inspector.
• Wire rope examination against discard criteria.
• Anchor and davit socket inspection and proof load testing where required.
• Coverage study: mapping the reach of the equipment against the current façade, including additions since installation.

The report should state whether the equipment is fit for use, defects by priority, the date of the next periodic and major inspection, remaining service life, and any elevations not covered.

• Repair of defects found at inspection; rope replacement; brake and hoist overhaul.
• Control modernisation: replacement of controls and electrical systems on a sound structure, often the main mid-life investment.
• Track and fixing refurbishment with renewal of the roof membrane at penetrations.
• Replacement of the unit at end of structural life, with crane lift, roof works and recommissioning.
• Strategy change: replacing a BMU with davits or rope access anchors where the façade allows, or adding a monorail or davits to cover a gap.
• Façade restraint installation where the cradle has none.
• Anchor replacement and recertification.

• Records: restore the logbook and keep it with the equipment.

Periodic inspection and servicing are a recurring contract per unit. Major inspections and control modernisation are lump sums. Replacement is a lump sum including crane hire, roof works and commissioning. Where equipment is out of service, hired access (swing stages, rope access or mobile platforms) is a recurring cost for each cleaning and inspection cycle.

Inspection and certification are code compliance; servicing is repairs and maintenance; modernisation and replacement are lifecycle. A major inspection is often the check line that sizes a replacement envelope.

• Australia. BMUs are designed to AS 1418.13 and used, inspected and maintained to AS 2550.13, which sets the logbook and certificate formats; their designs are registrable plant under the work health and safety regulations. Regulators have issued safety alerts on BMU stability and on major inspections for units more than ten years old.
• United Kingdom. Equipment lifting people needs a thorough examination at least every six months under the Lifting Operations and Lifting Equipment Regulations 1998, alongside PUWER 1998 and the Work at Height Regulations 2005. BS 6037-1 covers permanently installed suspended access equipment and BS EN 1808 the safety requirements for suspended access equipment.
• United States. OSHA 29 CFR 1910.66 governs powered platforms for building maintenance; 29 CFR 1910.27 requires rope descent anchorages to be inspected annually and certified at least every ten years. ANSI/IWCA I-14.1 and ASME A120.1 set further requirements for window cleaning and building maintenance platforms.

• Logbook, current periodic inspection certificate and the last major inspection report.
• Plant and design registration and load test records.
• Maintenance contract and service reports for the last two years.
• Façade access strategy and any coverage study.
• Anchor certification records and the rigging plan.
• Manufacturer support status for the controls.
• Rescue plan for work at height on the façade.