Old World Craftsmanship with Modern Technology
Drones Add Efficiency for Historic Restoration
Drones allow building owners, architects, engineers, contractors and other team members to view and inspect areas otherwise too high or hidden to easily access and assess. Technology continues to improve the means and methods of building construction and maintenance, improving buildings’ performance and extending their useful life. Sometimes, that technology can also improve work flow of the team, saving time, money and reducing risk of injury to crew members. The introduction of drone or unmanned aircraft systems (UAS) technology to the field of masonry restoration does all of this.
Designed by the military for their own use, drones were quickly adopted for other applications, including recreational, scientific, agricultural and construction. Drone photography is becoming an industry in and of itself, requiring high quality equipment that takes high resolution images in durable casings that can be controlled with accuracy and in tight and/or congested spaces. As popularity grows, technology advances as quickly as possible. We are now even seeing industry-specific hardware and software advancements that aid in the collection, management, processing and storage of drone-captured data. The model we currently use on job sites is about 16''x16'' and weighs approximately 3 lbs. It has about a three-mile flight range and can stay in flight for nearly half an hour. The 4K camera feature ensures professional-quality images, raising expectations on what’s possible for existing building repair and restoration.
Masonry is the material that built our cities. Even with the advent of steel-framed skyscrapers in the early 20th century, buildings were clad in masonry: stone, brick and terra cotta. Occasionally, a decorative piece of terra cotta or another element adorning those nearly century-old buildings falls off, potentially placing people and property below at risk. Because of this, many cities require that buildings undergo periodic façade inspections to try to ensure the integrity of the cladding units and safety of occupants and visitors. Change in ownership may trigger a required façade inspection.
Introducing drones to the façade inspection process is a game changer for large buildings. Now, a mason contractor’s drone operator can take 2000 photos in three days, then spend a few days labeling and corresponding photos to locations all over a building. Photos showing things like missing mortar, spalled, broken or missing masonry units, cracked masonry or caulk joints, displaced masonry, corroded or swelling steel or corrosion staining give masons and engineers enough information to estimate many repairs and identify areas that may need further (human) inspection.
Further inspections may include sounding, or tapping a unit to listen for hollowness, which may indicate internal cracks, or making an exploratory hole to inspect condition of anchors and other internal components, find causes of damage and to determine severity. Actual time, number of crew members, materials and equipment on-site are greatly reduced, all resulting in lower costs from the outset, while providing owners more accurate and thorough assessments than ever possible before. Owners may be presented with the façade assessment, a prioritized list of repairs, quotes for completing the work and photographs highlighting the areas that need work for their records.
Without the use of drones, façade inspections of high-rise buildings are labor intensive, requiring a structural engineer or registered architect (usually in conjunction with a mason contractor) to perform the inspection. Mason contractors typically submit a proposal just to do an inspection, depending on the building, may take a three-person team two- to three-months and cost $100,000 to $200,000. Permits must be applied for and granted, scaffolding would have to be erected, with consideration for the needs of swing scaffold, repelling, sidewalk protection and/or aerial lifts.
Taking advantage of drone photography could increase the safety of the public and mason contractor crews because there is less time on site working. Even if the drone photos identify areas that require human inspection, there is likely less scaffolding that needs to be erected and/or reduced need for swing stages or suspended scaffolding, which reduces a potential accident or injury to the crew. It also reduces the time pedestrian walkways may be closed. Because inspection can be accomplished so much more quickly, the time to inspect the job, estimate repairs, award contracts and begin work repairing loose or damaged units reduces the risk of further failure or pieces falling to the ground below.
Use of drones may increase safety as the substantially lower cost may interest some building owners who, although not required by law, would like to have inspection done for liability reasons. Sometimes when inspections are not required by law and it is not necessary for an engineer to sign off, they are attempted with binoculars from the ground and may not be completely accurate. Accurate inspections allow owners and property managers to make maintenance and repair decisions with knowledge about actual and/or potential property damage risks as well as risks to occupants or passers-by.
Becoming a Drone Operator and Accounting for Liability
Incorporating drones into construction isn’t as simple as simply purchasing equipment and letting it fly. The Federal Aviation Administration (FAA) implemented a mandatory online registration system for all UAS weighing more than 0.55 lbs and less than 55 lbs in 2015. According to the FAA, 110,000 UAS were registered by the end of 2017 and their prediction is that there will be more than 450,000 commercially-operated drones by 2022. As the number grows, requirements will surely change to accommodate needs.
Even today, the FAA regulates drone operator certification. The test for certification includes components on reading aerial maps, identifying safety zones, establishing flight patterns, knowing when and why one may need to communicate with air traffic controllers. FAA guidelines also mandate that drones only operate within the controller’s line of sight and that a drone can fly only up to 400' above the level that the operator is located, even though drones are capable of flying miles high. This is like remaining within posted highway speed limits, even though your vehicle is capable of driving much faster.
In addition to FAA rules and regulations, the insurance industry has standards regarding drone operation for contractors. Typically, contractors waive aircraft coverage in their insurance policies. However, it would need to be added when using drones or the company is exposed to liability associated with any damages or injuries resulting from a drone crash. Additionally, contractors should develop and provide employee training programs for all drone operators to minimize risk and liability. Everyone considering commercially operating a drone should check with their insurance agent for coverage to suit their needs.
In densely-populated urban areas, cell phones, telecom and Wi-Fi signals may interfere with drones’ GPS signals making drone operation a bit risky. Wind and narrow spaces between buildings may be obstacles to smooth drone operation. However, benefits usually outweigh the risks.
A mason contractor’s drone operator can take 2000 photos in just three days
Modeling and Archiving
Using photographs captured by the drone, dimensions are estimated by counting masonry units and taking specific field measurements during survey. A model of the building is created in Autodesk Revit 3D software and all required work can be detailed. Models clearly and concisely convey scope, scale and detail of work to owners and foremen, taking guesswork out of the equation.
Arch Masonry prepared a 44-slide presentation with more than 75 drone photographs showing areas of concern.
Built in 1903, the Beaux-Arts Union Station train station, designed by Daniel Burnham and considered one of Pittsburgh’s most architecturally-significant buildings, was adaptively repurposed into apartments in early 2018. As part of the process, Arch Masonry conducted an inspection of the rotunda and apartment tower to determine what masonry repairs were necessary. It was determined that the decorative terra cotta cornices, medallions, accent pieces and arches needed to have mortar joints repointed and pieces of the terra cotta needed to be repaired or replaced in order to prevent water from entering the structure. Other items identified included roof drain repairs, structural steel anchor repair or replacement as necessary along with cleaning and painting rusted columns, beams, plates and girders. Arch Masonry prepared a 44-slide presentation with more than 75 drone photographs showing areas of concern. Working with a fixed budget, the owner opted to prioritize the work and create a schedule of repairs to complete as budget allows and/or need increases.
Arch was subsequently awarded the contract to repair all the masonry required to meet the engineer’s specifications per the inspection and additional repair work to the property, allowing the project to proceed as scheduled.
Ultimately, use of the drone brings value to the client
For Arch Masonry, Our Lady of the Angels Bell Tower restoration was the project that best demonstrates the value of a drone for inspection and estimating purposes. This project is an example of one where no inspection was required by law and previous inspections of the 100' tall bell towers had been performed by using binoculars and photos from the ground. The height of twin towers and their steep roofs make access difficult. Though it was clear restoration work was necessary, this project was bid several times, but the church’s financial body did not approve the work.
However, once we provided drone footage and trustees could see the damage up close and realize the serious nature and risk of masonry failing at the top of the bell tower, work was quickly approved. CAD drawings detailed restoration areas and work to be performed. Restoration included cutting out and repointing mortar, resetting loose brick units, recaulking at stone sills and epoxy crack injections at stone ledges and columns.
The brick church building was designed by John Comes and completed in 1901. The Catholic Diocese of Pittsburgh had been through a consolidation in 1993 and is undergoing another consolidation now, reducing the total number of parishes by about two-thirds. In order for Our Lady of the Angels to maintain viability and vitality and survive the consolidation process, it must be structurally sound and have a long-life expectancy. Resolving existing problems before they become bigger problems eliminates the risk of more extensive property damage and puts the building in a better position to last another century as a home to its parishioners.
Other Opportunities for Drones
Drones are changing the way Arch Masonry is approaching masonry restoration and clients are onboard. We look forward to increasing the opportunities in which we can use this technology to aid our clients by improving our access to and transmission of information. Time will tell how we continue to integrate drone photographic capability into restoration and new construction projects.
Elsewhere in construction, contractors are using drones for excavating and site work, determining area and volume of earth to move to or from an area. Drone photography footage is great for promotional images of finished projects, but also useful for process photos for craftsmanship quality control as well as to analyze where and the way space is used for staging materials, for example. Making simple improvements along the way makes the job more efficient. There are many ways that using drone photography improves the efficiency of the mason contractor, but ultimately, use of the drone brings value to the client.