A large BMU moves across the incline of an industrial roof.

BMU Systems

Applied Technical Services performs inspections on client BMU systems to ensure they continue to operate safely and in compliance with applicable regulations. The higher the working environment, the more crucial it is that effective measures protect the workers scaling façades to clean windows, perform repairs, and complete other facets of a facility’s exterior maintenance requirements. Our commercial services division provides their cumulative decades of consulting engineering expertise to help clients remain compliant with worker safety regulations.

As one of the most advanced types of façade access systems, Building Maintenance Units (BMUs) are required by the ASME 120.1-2021 industry standard on buildings taller than 490. People may also refer to a BMU as a Roof Rig, Window Washing Rig, Roof Car, or Roof Carriage, but they all refer to the same category of façade access system.

These systems commonly consist of a few major components, including a suspended scaffold which carries the at-heights worker and controls their elevation by raising and lowering them; a remote-controlled carriage that moves the suspended scaffold along the surface of the building façade; and a roof-mounted track system along which the carriage travels. This complex system of machinery enables workers to access the entirety of a building’s façade but requires maintenance and regular inspection to ensure its continued safe use. ATS’ commercial services division helps clients verify the condition of their equipment and identify any necessary steps to keep it running smoothly.

How ATS Commercial Services Can Help
ATS’ commercial services group performs a variety of inspection and consulting engineering work on a wide array of commercial and residential buildings. As they apply to client BMU systems, we offer:
New Construction Consulting

ATS’ Professional Engineers offer consulting services in the planning and construction phases of erecting a building that requires a BMU system by ASME 120.1-2021. These safety and structural experts can help building owners design and implement the BMU system that best serves their facility’s needs.


As specified by 29 CFR OSHA 1910.66, BMU systems must undergo a top-to-bottom inspection before entering service for the first time after initial installation or any major alterations, such as extensive repairs. The standard then requires that these systems undergo regular inspection at intervals specified by the manufacturer to ensure the continued safe operating conditions of the equipment. This regular inspection schedule includes both annual comprehensive assessments (encompassing the platform, track, trolley, controls, and all other subsystems) and 30-day assessments. All of ATS’ BMU inspection services are performed under the direction of a Professional Engineer.

Negative findings commonly arise from not meeting service requirements or a lack of maintenance on the system. Whatever the case may be, our inspection specialists recommend appropriate remedial steps and maintenance actions in their final reporting.
Performance Testing

An important component of periodic inspections, ATS conducts performance testing on parts known to stress and wear, such as the limit switches, brakes, bearings, gears, and wire ropes. These performance tests determine whether the parts in question are sound enough to ensure maintenance personnel can safely operate the BMU. Their condition will vary depending on how long the individual components have been in use, whether the system has been used only as appropriate to its design, and other factors. All of ATS’ BMU inspection services are performed under the direction of a Professional Engineer.


Building owners must receive and maintain records of certifications issued after every BMU inspection. These records each bear the date of the inspection and the signature of the person who performed it, affirming that the system is safe for personnel to operate. ATS provides all necessary paperwork to help clients comply with the relevant documentation requirements.

3rd Party Quality Control

When BMU system inspection findings indicate a need for maintenance or repairs, ATS can assist by coordinating with well-known maintenance and service providers. Furthermore, our Professional Engineers offer 3rd party quality control wherein they work in an observational and advisory role to independently verify the work is performed efficiently and correctly.

Retrofit Consulting

Many buildings erected before the publication of ASME 120.1-2021 do not have a BMU system as required by its implementation. ATS helps building owners retrofit their facilities to achieve compliance with applicable standards and regulations. Our Professional Engineers offer consulting services to help clients design the BMU system that best meets their façade maintenance needs and identify the most appropriate service provider to install the new fixture efficiently and effectively.

About Applied Technical Services

Applied Technical Services was founded in 1967 by a trio of engineers serving local businesses from their shared office in our founder’s basement. The five decades we have spent in business have seen ATS grow immensely — both expanding the breadth of our services and deepening our pool of expertise. We now constitute a multidisciplinary firm that employs over 1,000 Professional Engineers, chemists, inspectors, calibrators, scientists, forensic investigators, metallurgists, and trainers to answer the varied needs of clients operating around the world. Although we serve a great many with our other consulting engineering services, our BMU-related capabilities solely benefit the construction and commercial properties industries.

Our Commitment to Quality
ATS upholds a variety of policies to ensure clients enjoy the best customer experience we can provide:
If your building needs consulting services regarding an in-service or planned BMU system, contact ATS today. We take a closer look!

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