Do you live in a building? Work in a building? Or own a building? Do you admire from afar not only how those buildings look aesthetically, but also how they keep you dry and comfortable when the weather is inclement? The exterior envelope of typical buildings is designed and maintained to achieve a dual purpose, to make a functional building that is both aesthetically pleasing and weather-tight. However, the exterior conditions of buildings may be ignored over time until deterioration has occurred and subsequent air and water intrusion have penetrated the interior.
The cost and risks associated with exterior inspections are the most common reasons building owners provide for failing to evaluate the exterior condition of a building envelope. However, these hurdles can be overcome through the use of drones. Drones provide close-up high-resolution imagery and videos and can be used to inspect a building’s exterior, periodically, without a person ever leaving the ground. The use of drones for building observation and inspection services can provide many significant benefits to building owners.
Reduced Costs – To perform a traditional, detailed exterior inspection a building owner would need to hire a team to install weights and rigs for inspection platforms called swing stages. The swing stages, which can be limited in width, would then need to be moved up and down the building as well as side to side. Some municipalities also require additional sidewalk protection scaffolding to be installed when working above areas where the public may have access. A drone, which can access the full height of a building without the constraints of a swing stage, can provide visual documentation of the building in far less time, with far less personnel involved, and with less risk to pedestrians below, resulting in both cost and time savings.
Safety – Hanging people off the side of a building or a steep sloped roof, as is required for traditional inspections, always comes with risks. The Occupational Safety and Health Administration (OSHA) has recorded approximately 145 suspended scaffold/swing stage accidents since 1984. While this type of work is regularly performed safely, would you want to be the one riding up or down the side of a building and risking possible injury?
Certainly, the one main disadvantage of the use of a drone is the ability to touch, feel, and probe the area being inspected to check for loose material or the adequacy of waterproofing elements such as sealants and flashings. However, in place of the less-flexible building-wide drops or scaffolding, and by making use of the information gathered by drone, a qualified operator can recommend the best place to perform strategic, tactile hands-on inspections.
While the use of a drone is much safer and more cost-effective than having inspectors on ladders, lifts, or repelling down the side of a building, there are several considerations one needs to keep in mind in advance of simply having a drone pilot show up and start flying around the building.
What Are The Legal Requirements?
The Federal Aviation Administration (FAA) is the primary governing body for the regulation of drones for commercial use. To become a licensed commercial drone pilot, the FAA requires a technically detailed test of the rules and regulations governing the use of drones along with a refresher exam every two years to keep an FAA Part 107 drone license current.
Principal considerations and requirements as they relate to building inspections include:
- Local laws limiting the use of drones
- Weather limitations
- 400 ft height limit above and around the structure
- Visual line of sight
- Low Altitude Authorization and Notification Capability (LAANC) approval
- Building occupant notification and privacy requirements
- Proximity to military or other restricted spaces
All drone pilots are trained to perform a number of checklist tasks before any inspections are performed. In some cases, there are local laws and/or flight restrictions in place that would prevent or curtail drone usage, especially near military and aviation facilities. For example, New York City requires a permit with the police department for any drone use, and Washington DC is designated a “Special Flight Rules Area” which requires pre-approval by the FAA.
While these cities may be the exceptions regarding local requirements, there are a number of other factors to consider before a drone can be flown for building inspections. One of the most important of these factors is the weather. Depending on the type of drone, the weather may overcome the drone’s ability to properly function. For example, a drone with a maximum speed of 35 mph may not be able to advance when fighting 35 mph winds, and that is without considering the wind tunnel effects of urban buildings which may further exaggerate certain weather and wind effects. Thus, many drone operators will limit their services to locations where the maximum wind speeds are known to be 20 mph or less. Rain and snow are two other considerations. While many drones are capable of flying in moderate wind, they also have a number of collision and positioning sensors that can be affected by raindrops or snowflakes obstructing the sensors.
According to FAA regulations, drone operators are limited to a maximum altitude of 400 feet above the ground or even lower than that when flying adjacent to an airport. However, if a building taller than 400 feet is being inspected, the operator is allowed to fly up to 400 feet above the roof line of the building. For example, if a building is 1,200 feet high, the drone operator is allowed to fly up to 1,600 feet above the ground and no more than 400 feet horizontally on either side of the 1,200-foot building footprint. Fortunately, for inspections, this is not a practical limitation because it is typically beneficial for an inspector to place the drone closer than 400 feet from the building being inspected.
A drone operator must keep the drone within sight at all times. This visual line of sight (VLOS) requirement can be accomplished with the use of visual observers that would keep in constant visual contact and communication with the drone pilot, should the drone move around corners of the building and out of sight of the pilot.
Privacy laws for drones, and any images they may capture from inside a building being inspected, vary from state to state. Regardless, it is good practice for inspectors to advise occupants and tenants that a drone performing exterior surveys may inadvertently capture views of interior occupants along with a protocol for how those images will be used, if at all.
Drones can also be used to capture thermal imaging of building exteriors which may reveal locations of energy performance loss or moisture intrusion in the form of thermal anomalies. Drones can also be used to capture dimensionally accurate 3-D models or topographic elevation information for existing buildings or topography and landscaping.
The use of drones for inspections and the capture of building information is becoming common in the industry. Drones are excellent tools for viewing and documenting objects and areas that are otherwise very difficult or expensive to access. The limitations of information captured by a drone are clearly outweighed by the benefits.
About the Author
The author of this document is Tom Linus, P.E. and Managing Director at Ankura Consulting. One of his expertise is the evaluation of design and construction defects and associated liability as it relates to issues with building envelopes. As a subject matter expert and licensed FAA drone pilot he possesses the unique skill to identify, in real-time, potential building envelope maintenance and defect items. Learn more at: https://ankura.com/services/professional-liability-and-defective-construction
© Copyright 2024. The views expressed herein are those of the author(s) and not necessarily the views of Ankura Consulting Group, LLC., its management, its subsidiaries, its affiliates, or its other professionals. Ankura is not a law firm and cannot provide legal advice.