Usefulness of Probes to Identify Underlying Conditions
By: Joe Czaszynski
A comprehensive building envelope restoration project is usually a costly venture that addresses most or all of a building’s issues in an effort to restore the façades, roof, garage, etc. as close as possible to their original condition. Unfortunately, since these types of restoration projects are expensive and disruptive, they are likely to be put off until absolutely necessary, or required by law.
When a building envelope consultant performs an investigation at a building that hasn’t had a comprehensive restoration project performed in the past 10 to 30 years, the likelihood of deleterious conditions beneath the surface that are not visible to the restoration designer is exponentially greater. This is also the case if, over time, minor, temporary or location-specific repairs were implemented to remedy deterioration or water infiltration instead of comprehensive restoration.
Probes to confirm existing wall/framing conditions, and to identify possible unforeseen underlying issues, should be performed during a building envelope restoration project. This is especially true if comprehensive repairs at a building have not been conducted for some time. If probes are not performed, these hidden/unforeseen conditions could arise at a later phase of the restoration project, ultimately adding time and expense to the project’s schedule and budget.
An example would be the steel structure buried within the building façade. Signs of steel deterioration that requirefurther investigation are often evident. Rust colored stains on a façade, along with spalled, cracked or bulging masonry, are all clear indications that water might be contacting the structural steel. These telltale signs are not always present, however, if for example they are covered by a coating. In either case, probes should be performed to inspect the structural steel and determine the required repair and maintenance.
During our investigations, we often come across a number of poor drainage conditions and waterproofing details, especially at older buildings. A lack of weep vents or through wall flashing prevents infiltrating water from properly exiting the façade. Additionally, if a non-breathable (non-permeable) coating has been applied to the building in an attempt to prevent water infiltration, this problem is compounded. Over time, water will deteriorate steel, destroy structural connections, and could eventually cause a disastrous structural failure. This is a reason why Sullivan Engineering strongly recommends water permeable coatings be used if/when a coating is applied to a façade. As you can see, it’s critical to perform recommended probing to see hidden conditions, regardless of our visible findings at a building.
Similar to building facades, structural concrete decks in parking garages contain steel reinforcement. If the concrete is cracked or uncoated, water might be penetrating and causing the reinforcement to deteriorate. Rust colored stains and cracks at the parking deck surface, or at the underside of an elevated parking deck, are again signs that this is likely occurring. Probes throughout a parking deck would once again help determine the condition of this reinforcing steel.
Typically, flat roof systems are comprised of several components (i.e. deck, insulation, cover board and waterproofing). Water can get trapped within these components and damage the roof’s framing or insulation. Unforeseen insulation or structural issues could result from prolonged water infiltration at a flat roof that is not remedied in a timely manner. A soft or spongy roof deck surface is an apparent sign of infiltrating water issue; however, probes of the existing roof system will offer a clearer indication of the condition of the framing and insulation below.
Underlying or unforeseen conditions at a building are always a concern when designing a repair or restoration. A project’s timeline or budget may be inaccurate if these possible issues aren’t considered. These conditions could also be potentially dangerous if they remain hidden until a failure occurs. While probes add some time and cost to restoration projects, they allow the designer to anticipate repair, replacement and maintenance of existing reinforcement, which in turn, enables them to provide a more realistic overall design and construction budget.