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Signs of Distress: Recognizing Construction Deficiencies that Result in Water Intrusion, Damages, and Mold

By George J. Inglis

May 7, 2015

Property Managers routinely get calls from residents requesting immediate action to address signs of physical distress associated with their residences.  Common indications of problems include water leaks, stains, ice dams, blistered paint, mold on interior surfaces, or other visible issues on exterior cladding and surfaces. When responding to a call, it is important for Property Managers to properly identify and diagnose the full extent of a problem, and not just treat the symptom; otherwise the initial cause of the problem remains, with a high likelihood of continuing damage.  One example would be to perform a superficial cleanup and repaint damaged interior finishes without identifying and correcting the cause(s) of damage.  When the causes of the distress are not diagnosed, corrected, and properly abated, damage such as mold and deterioration of building elements will return.

The evaluation of building problems is a process known as Building Diagnostics, and is much like the process a doctor will perform examining a sick patient. In building and construction evaluation there are at least 6 steps to diagnostic investigations which are generally necessary to properly understand and correct a building problem. These include:

1. Contact Property Managers to investigate the history of complaints from residents and maintenance personnel, and identify prior steps taken to address the problems.
2. Analyze available construction documents, manufacturers’ instructions, industry standards and applicable building codes.
3. Observe conditions at building interiors and exteriors for visible issues and damages.
4. Perform a moisture survey with a moisture meter or infrared scanner to identify areas of potential issues.
5. Perform invasive examinations (test cuts) to confirm the extent and determine causes of the damage.
6. After the investigations, contact the appropriate design professionals and qualified, experienced contractors to develop an effective solution.

To define the potential causes of a problem, it is important to understand how exterior walls and roofs of buildings function, as there are differences.  Buildings “keep weather out” through the building envelope, which includes roofs, exterior walls, windows and doors, and similar enclosures.  The two main types are called “barrier” systems and “rain screen” systems.

A barrier system is intended to always keep the elements out, and in order to be successful, all assemblies and penetrations must be properly installed and continually maintained, including joints, flashings, sealants, and utility penetrations.  There is no margin for error, since these systems rely on water never penetrating the building, and there is no means for water to get out if it does enter.  An example is a barrier exterior insulation and finish system, which by design is applied directly to the exterior of the building structure.

In barrier systems, small issues such as a failed sealant joint, damaged flashing, or any un-planned gaps or cracks must be immediately addressed to prevent leaks; however, the means of water entry is often not evident, and the damages caused may be ongoing for years until detected.  Even when damage is evident, the location and means of water entry is often difficult to identify.

Another type of building envelope is a rain screen or drainage system. This type of system is designed to manage incidental water infiltration with provisions to direct water back to the exterior of the cladding, and typically include spaces between the façade and the structure to control moisture.  An example is a brick cavity wall that may appear to be a barrier system, but actually includes a 1- 2 inch air gap behind the masonry, secondary weather barrier materials on the building structure, and flashing and weep drains to properly direct water to the exterior.

One common sign of distress on masonry or manufactured stone veneer walls is efflorescence, usually a white chalky coating that appears at concentrated locations on the façade. Efflorescence results from water that penetrates the cladding, saturating the materials in the cement of mortar joints or underlying construction, and then leeches salts and minerals back onto the surface of the building.

A common avenue for water infiltration behind masonry is from the areas surrounding windows. Proper selection, installation, and maintenance of materials and components are critical. Sometimes a well meaning maintenance person armed with a tube of caulk will respond to a complaint of water intrusion and address the problem by caulking drain holes of windows and doors and weeps in masonry walls. Sealing any of these necessary drain holes or weeps inhibits water drainage to the building exterior potentially making water intrusion and damages worse.

Another common sign of distress observed in northern climates is ice damming, which can be observed after a heavy snow fall, and is common on homes with complicated rooflines, cathedral ceilings, and skylights.  Heat from the living area melts snow on upper roof surfaces, resulting in water running down the roof until it reaches the edges, eaves and soffits  which are unaffected by the interior heat, and remain below freezing temperatures. The water then quickly refreezes, forming ice, blocking gutters and creating icicles.  Serious ice damming can cause water to back up under roofing materials, damaging the structure, entering the building and leaking into interior spaces.

One construction technique as a defense against damages from ice dams as required by building codes is an adhered “rubber” membrane applied under shingles, roof edges, extending up the sheathing to prevent water entry.  However, proper roof ventilation, attic insulation, and prevention of warm air leaking from the interior to the attic helps keep attics cool and reduce snowmelt.  This also helps keep the attic cooler and less humid in warmer months reducing condensation and the potential for mold growth.

As building codes become more restrictive, especially with respect to air leakage and insulation; new buildings are generally better insulated, less drafty, and less costly to heat and cool.  However, tighter buildings are less forgiving when materials and systems are not properly installed or maintained.  Buildings eventually demonstrate some sign of distress when there are problems, and when distress is observed, building and construction evaluations and diagnostic investigations should be utilized. Property managers should take care to enlist properly experienced professionals and knowledgeable, qualified contractors to carefully evaluate such conditions and assure a successful outcome.