Façade inspection and restoration is a complex process involving numerous elements; the following are typical processes. However, City Mandated Façade Ordinance Inspections may require specific procedures to meet the municipality’s requirements.
The process begins with an historical analysis. How has the building been maintained over time? Has the façade been upgraded or modernized through its lifespan? If possible, the restoration team should review original blueprints and other relevant drawings and reports. Likewise, if there were prior improvement programs, the restoration team should review all related documents. Before addressing the façade’s physical condition, it’s essential to have a complete understanding of its original construction, including what materials and design approaches were used. Similar information is required for all maintenance and improvement work performed throughout the building’s lifespan.
It’s not just the individual building’s history that’s important. Knowing when it was built, restoration professionals can gain a good understanding of its nature and façade. For example, buildings built prior to 1870 typically featured load-bearing construction. Conversely, buildings built between 1870 and 1920 tended to feature framed structural systems, curtain wall systems, and newly developed cladding materials. After 1920, construction evolved to modernism and then post-modernism, each with its own characteristics. Knowing the structure’s history gives restoration professionals a good start in determining how to proceed.
Once the historical research is complete, following is an on-site exterior assessment to determine the façade’s relative condition. The initial assessment usually revolves around a visual inspection conducted by an expert restoration professional, often utilizing scaffolding systems, boom lifts, or even rappelling to gain a close-up, hands-on view of the façade elements. Just as a doctor may examine joints through an arthroscope, the façade professional may use a boroscope to examine the cavities and anchorages of a building’s veneer. Photographic documentation is performed so the restoration team can note any damage while developing an action plan. Alternative methods include observation through high-powered binoculars and unmanned aerial vehicle
(UAV) inspections.
Visual observation isn’t the only investigative method utilized. Sounding is a process using hammers and other equipment to tap on façade sections and determine if there are voids beneath the façade exterior. Trained restoration professionals can recognize the different tones that occur during sounding, and what each tone means while assuring the façade is not damaged. Typically, mason’s hammers are used to sound concrete, brick, and stone exteriors and wooden mallets are used for terra cotta.
Other non-destructive testing methods include ground-penetrating radar (GPR), used to “see” behind the surface of the facade; sonar, used to determine the condition of interior sections through impact-echo and impulse-response methods; water absorption with RILEM tubes, able to indicate the extent of susceptibility to water damage; and infrared photography, which can show potential anomalies. These testing methods are all effective in identifying different types of façade deterioration.
There are many different types of façade deterioration. The most common include erosion and disintegration, most often caused by rain, snow, and other extreme weather; cyclic freezing and thawing; salt crystallization; façade anchorage corrosion; thermal stresses from extreme heat; restrained movement; and UV degradation caused by direct sunlight. Additionally, improper past repairs can also cause significant destruction.
Each type of damage requires a unique type of repair. The most common façade repairs include replacement of joint sealants, re-pointing mortar joints, re-pinning masonry, patching or replacing masonry units, or even partially rebuilding wall sections. In addition, addressing water-leakage issues may involve masonry removal to install through-wall flashings, replacing copings, or repairing roof-to-wall interfaces.