A Multi-Disciplinary Approach to Mitigating Moisture Issues in Buildings

There are so many ways in which the presence of water can affect a building’s structure and function – keeping it out is a large part of the design consideration for exteriors, roofing and finishes. The most problematic damage can lead to structural integrity issues like rot, corrosion, microbial growth, and/or pest infestation; all of which can lead to and health issues for occupants. Surface tension and capillary action can migrate moisture away from the initial spot of intrusion, causing even greater impact.

However, despite all the best proactive measures for sealing a building and monitoring for water intrusion, it does sometimes happen! Suppose that after conducting a Property Condition Assessment as part of a commercial real estate transaction, or as a current property owner, you have found moisture somewhere on the property. Now what do you do?

A property condition assessment can identify indications of water intrusion, but a more thorough follow-up study (also referred to as building forensics) is essential for determining exactly what the issue is, where it is, and through consultation with specialists, what the best solution is. For example, stained ceiling tiles or interior wall surfaces is a very common sign of historic or active water infiltration. But the staining or water damage is only an observable symptom of the real issue. Pinpointing the source often requires a deeper, more intrusive investigation, including gaining access to confined areas not accessible during baseline ASTM PCA observations. These additional forensic investigations involve applying knowledge of building systems and components in conjunction with experience of common failure modes in order to follow the path to the most probable area of the water intrusion. A pinhole leak in a roof can fester over time, allowing water to enter the building envelope. Gradually, that water can migrate and flow to other areas within the building and manifest in an area far away from the original leak. A loose shingle, a wayward nail, a puncture in the roofing membrane, a backup of a roof drain, vegetative growth, failed flashing or sealant, HVAC condensation, damaged plumbing components or a myriad of other concerns can all lead to the problematic presence of water in your building. Having the proper knowledge and experience enables Partner to diagnose the issue and recommend the proper corrective actions.

And water infiltration isn’t just a problem above ground. Depending on the area of the country, construction methods, soil, and water table level, basement foundation walls also present opportunities for water to enter the building. For example, during a 1-inch rain event, 1,250 gallons of water fall on the roof of a 2,000-square-foot house. Without proper grading, roof drainage, waterproofing, and sub-terrain drainage methods this water can stagnate and perch at the foundation walls and because of the increased pressure, it seeks the path of least resistance into the basement.

A forensics investigative team is therefore an indispensable resource for elucidating what can be complex investigations and engineering issues, both in terms of locating the source, as well as assessing the extent of damage and how to best remediate it. Moreover, “simple” signs of minimal moisture or leaking often belie the true extent of the damage. The following case studies illustrate this perfectly.

Small Drips, Big Problems: Two Case Studies Partner performed a Property Condition Assessment on brand-new high-end condominium high-rise in the Midwest. The building was constructed with the new must-have amenity for residential developments; a rooftop pool. During the PCA, the engineering consultant noted signs of water intrusion in the lobby’s ceiling tiles, potentially signaling a roof leak. The recommended subsequent forensics investigation methodically examined the hidden and confined areas through ceiling hatches and access panels – looking at the pattern of staining from the regularly occurring moisture intrusion. These observations followed horizontal structural members, metal decking materials, and ductwork to ultimately track the path of the water to the rooftop pool area located three stories above the lobby. The next step was to further examine the pool area to determine exactly how the water was entering the building. Was the water coming from the pool itself or the surrounding pool deck area? The process of elimination commenced and progressed from the easiest and least intrusive to the most invasive examination methods. The forensics investigation occurred during the off-season and the pool had already been drained and winterized. This allowed easy and direct observation of the pool liner which revealed a well-maintained surface free of any cracks that would provide a pathway for the water. In addition, maintenance staff had never observed a drop in the level of the pool water when it was in operation. The observable piping connections at intakes and drains appeared to be intact and properly sealed. We were comfortable eliminating the integrity of the pool and equipment as the entry point of the water. Next, the engineers flood tested the roof deck carefully, section by section and ultimately determined that the source of the leak was not a compromised decking system or waterproofing membrane. The lobby was still dry with no signs of moisture. Three days later, property management called us reporting water in the lobby. There had been no rain and the pool was empty – the only source of water was the flood test. Through further investigation of as-built drawings, additional interviews of maintenance staff, the general contractor, subcontractors, and architect, the culprit turned out to be a blockage in the secondary pool containment sarcophagus. The secondary containment was in place to provide a back-up drainage system for pool or storm water; insurance in case the pool leaked. It was meant to prevent the very issue that it was causing. When the drain became blocked, most likely with construction debris, the secondary containment would fill with storm water and overflow, allowing water to enter the building. Because the roof deck construction cross section included many levels of materials, the rain would often take several days to make its way to the secondary containment. This delay caused a false negative when originally suspecting rain water; the leak never coincided with a precipitative event, property management was convinced it couldn’t be rain water. Ultimately, the building owners had to clear the drain by removing and replacing the pool. This time making sure that all drains remained open and ready to operate as designed.

Another multifamily property, with an exterior insulation and finishing system (EIFS), retained Partner as a consultant after the owner noticed moisture under the window in one of the units. A forensic investigation was required to determine why this was happening. It could have been the result of something simple, like condensation running down the interior of the window, or something much more nefarious like the result of moisture intrusion somewhere at the building enclosure. After engineers moisture tested accessible materials and interviewed occupants to understand their activities, direct observation of upper story windows and exterior sheathing was conducted. In doing so, it was observed that the drainage system integral to the windows had been sealed with caulk. The new maintenance worker had mistakenly sealed all of the weep holes around the building, thinking that they had been missed during construction and were paths for insects and water to enter the building. Without a pathway for storm water to exit the window system, the only path for it to follow was into the building. The issue was compounded by the presence of the EFIS; a building component notorious for its inability to properly drain water that had found a pathway into the system. The water, without anywhere to go, started to rot structural components and provide conditions for microbial growth in the wall cavity. Over the course of the two years following construction, the water had caused so much damage that the entire façade had to be removed and a majority of the exterior sheathing and batt insulation and significant amount of the framing members had to be replaced. And don’t forget replacement of the windows. The repairs to the building took nearly six months and cost several million dollars to complete, and all because of a well-intentioned maintenance person.

Additional Building Repair Considerations In addition to forensic engineering investigations that determine the source(s) and extent of moisture damage, restoring your property may also involve the following inter-disciplinary services:

●Roofing specialists may need to inspect, repair, or replace part of your roof. A great way to proactively manage moisture issues is to invest in regular roofing maintenance activities, which can often catch issues early and extend the useful life of one of the most expensive building components. Furthermore, any transactional Property Condition Assessments should focus on identifying major roofing “red flags.” ●If your mechanical, electrical, and plumbing (MEP) systems, such as the HVAC system, are mounted in an area impacted by water infiltration, they might need to be moved or replaced by qualified consultants. If there is corrosion of any degree, in addition to impacting critical functions, there could be potentially harmful bacteria or other microbial growth that is being distributed throughout the building, impacting Indoor Air Quality (IAQ) or creating “sick building syndrome.” Impacted components must be cleaned or replaced. ●Whenever there are water intrusion issues, there are usually also Industrial Hygiene concerns. It may be prudent to have a certified industrial hygienist test IAQ, look for biologicals or other hazardous issues, and determine how best to abate them. ●A structural engineering and design team, in collaboration with subcontractors, may come out and repair parts of the building. In the case of building exteriors, this may involve a separate façade specialist. Water damage can significantly corrode structural steel members, or seep through the foundation and corrode concrete reinforcement.

If you are a current building owner, investor or facility manager, do not take even the smallest signs of moisture, water intrusion, or leaks lightly. Once it is visible, it may have done a lot more damage than the surface indicates. It may not be a big issue, but it could be. Be proactive, do the forensics and figure out where the source of the water is located. More importantly, be proactive in maintaining your building to prevent or minimize damage to begin with. In addition to an annual roofing inspection, consider a Facility Condition Assessment to better understand and maintain your building’s systems and help establish long-term maintenance activities and replacement budgets.

If you are conducting a Property Condition Assessment as part of a commercial real estate transaction, make sure the consultant performing the PCA is knowledgeable and experienced in the details of physical building assessments. If they don’t have cross-disciplinary experience with all of the possible building systems, they may not be able to recognize sophisticated signs of water infiltration and be able to properly recommend additional forensic investigations. A firm that can bring a multi-disciplinary services approach will be able to not just recognize potential issues, but also bring the resources to mitigate the problem when it’s needed.