Return to Forum Index

WATER INTRUSION: A CASE HISTORY


by Matt H. Nolton, P.E., C.B.I.E., and Richard P. Lundberg, P.E., C.B.I.E.

Water, we can't live without it, but we don't want to live with it! Water, especially rainwater, is a dominant force to be reckoned with in South Florida. To ignore water intrusion for any amount of time is simply a “pay now or pay much more later” scenario. Often times, building managers are faced with the most problematic water intrusion, which is the sporadic kind. It only occurs when a specific set of circumstances come to pass. For instance, only when the rain comes from the east, the wind is greater than 10 mph, or it rains for a duration greater than 30-minutes. These situations can be further complicated by occurring during the summer rainy season when the owner is not present.

This particular case history starts with a 26-story condominium building located in Southwest Florida. The building was barely four years old when Forge Engineering was first contacted about water intrusion problems. At that time, it was reported the building had experienced water intrusion at several locations (including a ground floor unit) since its construction and that the building manager had been dealing with the water problems with help from the original development team. The association and the building manager finally decided it was time to engage an engineering firm to help solve the water intrusion problems. We provided a proposal for the services but another firm was selected.

Approximately 24-months later, the building's new manager re-contacted us. We were informed that together with the original engineering firm, the previous manager and association developed a set of exterior coating specifications that were intended to put a stop to the water intrusion problems once and for all. The exterior coating work addressed a variety of water issues and included caulk replacement, wet sealing, delaminating stucco repairs, and crack sealing. Following completion of the extensive (and costly) exterior coating work effort, the plagued ground floor unit owners wanted confirmation that the water problem had been corrected before repairing and refurnishing the interior of their unit. The manager complied, but the test was a failure, as water was still entering the unit. Several attempts were made by the original consultant and waterproofing contractor to stop the leak without success. The only good news that came out of the water testing was that the entrance point of the water intrusion was narrowed down to the ground, second, and third floor exterior walls located at and above the area of the leak.

At this point, Forge was engaged to investigate and identify the source of the water intrusion and to provide remedial recommendations regarding waterproofing the affected area of the building. The exterior walls of the building were found to be typical masonry block infill wall construction faced with painted stucco. The exterior of the building in the area of the water intrusion included vinyl reveals, decorative stucco, and foam accents, tile-covered balconies, and cast-stone railings set on small knee walls. Prior to our involvement; significant effort had been focused on the cast-stone railings on the third floor balcony.

Following our initial investigation, the recommendation was made to remove the stucco finish from the knee wall and some decorative foam banding from a balcony that was two levels above the unit being plagued and adjacent to the exterior wall that was leaking. The removal of the stucco and banding allowed for the identification of various flow paths of the water intrusion. It was further recommended the remediation include the removal of the foam banding and more stucco so that additional areas could be inspected. Instead, the association opted to simply repair the water intrusion paths that had recently been detected and so directed the restoration contractor that had recently completed the exterior coating project. Hooray! The problem was finally solved, right?

Well, no the problem wasn't solved. The next summer came around and with the typical summer deluges and strong, swirling winds, the water intrusion appeared again. This time, Forge was engaged immediately after the event occurred. The corrective work that was previously completed was reviewed and then thermal imaging and moisture meters were utilized to identify the specific area in the ground level unit where the water was entering. Backtracking those results to the exterior wall led us to a small window at the corner of the building. Additional non-destructive and destructive testing led once again to the decorative foam banding. However, the recent repair efforts had sealed the foam banding. We had determined the water pathway was located behind the foam banding and through the block wall down to the ground floor unit, but we did not have an entry point that would allow the water intrusion. Some additional water testing of the foam banding and surrounding areas confirmed the water tightness of the banding. Other areas around the first and second levels were tested to ensure that other potential sources had not been overlooked.

It was clear that water was getting behind the stucco, entering the concrete block above the first level window, and coming out at the bottom of the window into the unit. Following an inch-by-inch investigation of the foam banding, a potential gap in the middle of a third level scupper was identified that was suspect for the leak. However, the hole was very small and did not appear big enough to allow the amount of water into the system required for the leak.

Water testing was then conducted on the balcony deck with the exterior of the scuppers closed. Water testing was completed for over 60 minutes, without seeing any results. Finally, water began to flow out of the area under the window. The source had been found.

We explored the hole in the scupper and found a much larger hole that had filled with some debris. Poor sealant details, the extension of deck tile into the scupper, and some cracked stucco all contributed to the water intrusion. When the wind was right and the rain event long enough, water would enter the hole, travel behind the foam banding (approximately 20-feet), penetrate the stucco, enter into the cavities in the concrete block wall, travel down two floors (approximately 25-feet bypassing the second floor), into the top of the window, down beside the window, exiting at the base of the window then enter into the ground floor unit.

If our original recommendations had been followed related to the removal of a section of the foam banding and stucco, the additional sources of water intrusion behind the foam banding could have been detected during the initial investigation, thus preventing the second go round of leak detecting.

In this case, the unit was plagued not by one source but by several different sources of water infiltrating behind the foam band. The sources would only allow water to enter when wind and rain conditions were just right. Rainwater is a continuing battle that managers face every day. Be vigilant in your fight and call an engineering consultant experienced in the investigation and remediation of water intrusion problems.


Matt H. Nolton, P.E., C.B.I.E., and Richard P. Lundberg, P.E., C.B.I.E.
are owners of Forge Engineering, Inc. located in Naples, Florida.
For more information, call (239) 514-4100 or visit www.forgeeng.com.

Return to Forum Index