Case Study: Spray Rack Water Leak Testing

Improving an existing testing method

Michael is a building science specialist with NEXUS. He has spent 15 years in the industry, with experience in both construction and consulting. His understanding of building envelope design and testing stretches far beyond standard testing methods. This expertise allows him to solve even the most troublesome building leakage issues.

Detail oriented; persistent; inventive. These are all characteristics found within members of the NEXUS team. We aren’t deterred by what others see as insurmountable challenges. Rather, we see them as opportunities to find solutions. This was the case when a standard spray rack, as designed, wasn’t up to the rigors of the task. Faced with a complex and potentially expensive water intrusion issue, my colleague, Jonathan Rowan, and I came together to develop a solution that would provide the flexibility necessary to allow us to quickly, and cost effectively identify areas of water intrusion.

What is a Spray Rack?

NEXUS is frequently asked to assess buildings to determine areas of water intrusion. To do this a water test is performed using an aluminum spray rack to help pinpoint the source of water intrusion. These spray racks are calibrated to ASTM standards, and are a convenient way to pinpoint areas of water intrusion. Spray racks are portable and can reach as high as a second story window. To reach higher areas, scaffolding or a lift is required. This is where the NEXUS team was limited by the spray rack itself, as scaffolding and lift rentals can be quite expensive, and a lift simply isn’t an option for buildings with unique architecture or that sit on a challenging site.

Ingenuity at its Finest

Both a challenging site and unique building architecture tested our building science professionals when a facility director for a large medical office building in Bellevue sought our help in May of 2016. NEXUS was asked to pinpoint areas of water intrusion along a large bank of windows that had perplexed the building’s facilities maintenance team for seven years. The building sits on a sloped site, which didn’t allow access to the highest point of the windows via a lift, leaving expensive scaffolding as what seemed like the only option. Rather than going that route, Jonathan and I suggested a third option - a retrofit to the spray rack that would allow the rack to roll along the face of a building. This eliminated the need for scaffolding or lifts and provided the flexibility necessary to quickly test a large area.

Making it Work

The retrofitted system, with the original spray rack in blue, and our system in red.

To prove this was a viable option, a wooden mockup was built, balanced, and tested. Once we were certain our retrofit wouldn’t affect the legitimacy or accuracy of the test, Johnathan and I built the steel rolling rack. Every detail was accounted for to ensure integrity. Wheels were chosen specifically for their ability to roll without damaging the window. Shoulder bolts were chosen as they act as an axle and allow the rack to maneuver along the face of the building. This resulted in a rolling rack that maintains the integrity of the original system, while allowing the flexibility needed to perform the assessment.

Putting it to the Test

Once built, we took our new system back to Bellevue, and positioned the spray rack so it could slowly roll up the face of the windows to pinpoint areas of water intrusion. Our test was done in a day and located numerous leak locations. In the weeks following, the window installer was called out to make necessary repairs. NEXUS was on-site to provide repair guidance and document the repairs. In the weeks and months after the investigation and repair, the water intrusion plaguing the structure has stopped.

The retrofitted system slowly rolling up the face of the windows.

[endif]--We were also able to use our retrofitted system to help locate an elusive leak at the recently renovated, historic McCarver Elementary School in Tacoma. A few months after welcoming students to their newly renovated space, teachers noticed areas of water intrusion in their second story classrooms, located just below an exterior scupper penetration. Initially, the general contractor and architect thought the scupper was to blame. However, after reviewing construction documents and performing a visual inspection of the building, we suspected the leak was coming from elsewhere. To rule out the roof, we used our rolling rack system to slowly and precisely move the rack. We then performed a Rilem Tube Test, which measures the quantity of water absorbed into the masonry wall. This revealed water was coming through the brick façade of the building’s penthouse, nearly 30 feet away from the classrooms that had the leaks. Our rolling rack system allowed us to rule out areas of water intrusion on the roof in an efficient, practical, and cost-effective manner.

The Rilem Tube Test helped located a mysterious leak at the historic McCarver Elementary School

Providing Improved Testing Methods

Issues of water intrusion can leave the most experienced facilities manager or builder stumped. The NEXUS team thrives when we are presented with these types of challenges as they force us to change and improve our work. Our decades of experience allow us to provide improved methods of testing. And develop solutions that go beyond the standard tools available.

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