Living buildings are starting to become a regular part of most downtown skylines. A decade ago they were seen as oddities that would probably fade away along with the craze in ‘going green.' Fast forward to today, and we can see that hasn't happened as living building facades have only grown in popularity. Which leaves us with the question: How do you perform maintenance on the exterior of a living building?
Depends on the living feature
There are many types of living structures available for buildings and vary from rooftop gardens to hanging panels that mount to the exterior walls of an office or apartment complex. While most living walls are inside a lobby or hallway, there are two major types of green facade support structures:
Modular trellis systems are lightweight rigid panels that can be installed either wall-mounted or as a freestanding system. Their applications extend to both short and tall buildings that have planters on the ground or along rooftops. These are great for when plant real estate is limited such as urban centers or where you have limitations on weight.
Cable and rope wire systems consist of high-tensile steel cables, wire trellis, anchors, spacers, and additional equipment. These types of installations are great for covering large areas like courtyards. Due to their flexibility and minimal installation needs you'll find this type of green facade support is widespread.
Now that we have at least a basic understanding of most green support structures, we now need to think about what method of transport will allow cleaners to get access to the building without getting in the way of the greenery.
Bosun’s chair, suspended platforms, and building maintenance units (oh my)!
The outside of a building needs to be cleaned just as much as its interiors because if left unattended the actual structure, cladding, and finish can become damaged. Doing preventative maintenance, such as something as simple as washing it, will save you money in the long run. If you want to install a living feature, you're most certainly going to need to have this done regularly to avoid any long-term damage or staining.
The next question you must be asking is: What kind of equipment do I need for my crews or maintenance contractors to access the outside of the building safely? The answer depends on a few factors that include the size of the structure, where your living features are installed, and lastly ground accessibility. Here are the three primary suspended access systems you will use if your building is over three stories tall.
Bosun’s chair
What consists of the Bosun's chair is a plank of wood or other material that is used to keep a single person suspended from the roof of the building. It should only be operated by someone who is specially trained on how to properly rig and use the chair as it is entirely manual. The chair depends on a controlled descent device that utilizes friction to lower the worker from the roof down to the ground. It does make for risky endeavors, which is why the new standards for Federal OSHA last year put a height restriction on it of no more than 300 feet. In California, the height limit for the Bosun's chair is 130'. If your building is taller than 130', then this method is not an option. While all components of the Bosun's chair are critical (which include the chair itself, the controlled descent apparatus, carabiners, lanyards, main suspension lines, safety lines, and shackles) the system is anchored to the roof using a permanent tieback anchor connected to the building's primary structure. Secondary safety lines are mandatory and must be connected to a second and redundant tieback anchor. Annual inspections and maintenance of the tieback anchors are required.
Suspended platform systems
The suspended platform system hangs on davit arms, outrigger beams, roof carriages, or monorails. This topside rigging equipment, when permanently mounted to the roof structure, requires an annual inspection and maintenance according to the applicable codes and standards. A qualified and trained professional should still operate this system, but it is significantly easier to manage than a Bosun's chair and works on taller buildings. The platform can vary in size from 3 to 52 feet long, allowing workers to optimize their efficiency while over the side of the building. Suspended platforms can be roof rigged (starting at the upper level) or ground rigged (starting at the lower level). Depending on the building height, roof rigging may be a requirement by the codes and standards depending on the jurisdiction. The suspended platform is supported by electric traction hoists that climb the steel wire ropes that are supported by the top side rigging system. Considerations need to be made for wind sway stabilization and electrical requirements.
Building Maintenance Unit (BMU)
Unlike the Bosun's chair or the suspended platform, the BMU is a permanent system that uses a gondola on a roof-mounted control box (machine house) that operates the system. The BMU is perhaps the best system to use for workers because it offers them a lot more options when working and is a more secure system. The BMU increases safety and productivity. Like other permanent installations, the BMU only needs to be serviced and certified once per year. BMUs consist of simple twin job models with short reaches to crane style machines with telescopic booms that locate the gondola on any point of the building's facade. These by far are the safest and most versatile of the three systems and are mandatory for buildings that exceed 490 feet.
These three systems will allow for any maintenance on the living features of your building. All three are available for any sized building, so it depends on your needs. If you have questions about what system to use, please contact us at 949-309-2820 or email us at consult@facadeaccess.com. Being in business since 1989, we bring facade access expertise and are ready to answer any of your questions.
