Determining Responsibility and Managing the Blame Game
When a brand-new, multi-million dollar gymnasium starts “raining” from its own ceiling fasteners—putting a pristine hardwood athletic floor at risk of catastrophic damage within months of opening—the financial and operational panic sets in immediately.
Facility teams face a brutal blame game: Is it a botched roofing installation, an HVAC and humidity control failure, or a costly design defect? The default reaction is often to start tearing into the roof or demanding expensive warranty claims, which frequently leads to bloated budgets, disrupted schedules, and zero real answers.
As our recent forensic investigation on a newly constructed gymnasium demonstrates, treating building moisture as a simple single-source failure is a recipe for wasted capital. When mysterious leaks pop up, the reality is often far more complex—and finding the truth requires looking at how indoor environmental dynamics and exterior envelope detailing collide.
Facility Description and Initial Observations
The building in question was a newly constructed gymnasium featuring a mechanically attached standing seam metal roof installed over a peel-and-stick membrane (or vapor barrier), two layers of 2-inch polyisocyanurate insulation, and a structural metal deck.
The primary complaint from facility management was active interior dripping occurring during and after rainfall events, as well as during periods of normal operation. This moisture threatened to damage the brand-new hardwood athletic flooring.
Initial site walkthroughs revealed several critical patterns:
- Location of Dripping: Most of the reported dripping occurred near the upper structural elements, specifically near the ridge and rake areas, generally within approximately 30 feet (or three structural trusses) of the exterior walls.
- Exiting vs. Entering Points: Water was frequently observed exiting through fastener locations on the underside of the structural metal deck. Our forensic team emphasized to the facility team that fastener locations represent where water leaves the assembly, but not necessarily where it originally entered. Water can travel considerable distances laterally or diagonally through panel joints, beneath ridge or rake components, along the vapor barrier, between insulation layers, through deck flutes, or along framing members before finding an exit path. Therefore, an interior drip location can never be automatically treated as the exact exterior entry point.
The Dual-Threat: Indoor Environmental Dynamics and Condensation
To evaluate potential environmental contributors, our team deployed data loggers and performed interior and exterior drone-based thermal imaging. The environmental data uncovered a severe potential for condensation:
- The gymnasium was being maintained at cold operating temperatures (approximately 55°F to 58°F, with supply air delivering around 54°F).
- Concurrently, the interior dew point was sitting around 58°F.
- Thermal imaging and surface pyrometer readings indicated that portions of the structural metal deck were measuring between 58°F and 60°F—placing the deck directly at or near the dew point.
When interior holding temperatures are maintained below the dew point of the ambient air inside a high-volume space, moisture will readily condense on cold structural steel surfaces.
Testing the Condensation Hypothesis
To test whether interior operating conditions were driving the moisture, the general contractor temporarily increased the building’s interior holding temperature. Following this operational change, widespread interior dripping substantially decreased, even following subsequent rainfall events. This strong correlation indicated that interior condensation was a major contributor to the original moisture problem under the building’s initial operating profile.
Secondary Findings: Legitimate Concerns for Exterior Water Entry
While adjusting the interior temperature mitigated a large portion of the widespread dripping, localized moisture persisted near specific trusses on the west and east sides following heavy rains. Furthermore, a thorough inspection of the roof’s exterior detailing revealed several conditions that raised legitimate concerns regarding exterior water entry:
- Butyl Tape Extrusion and Gaps: Butyl tape was observed extruding from horizontal and vertical joints. Visible gaps were present where the butyl should have remained continuously compressed between mechanically fastened components. Gaps were also visible between portions of the metal roof panels and the ridge or rake caps between fasteners.
- Fastener Installation Variances: Several fasteners appeared to have been installed at an angle rather than perpendicular to the substrate.
- Lack of Rigid Backing: Portions of the ridge and rake detailing appeared to have been fastened directly over the 2-inch polyisocyanurate insulation without a rigid wood or similar backer underneath to provide consistent support and compression under thermal movement.
Why These Observations Matter
Standing seam metal roof systems experience considerable dimensional expansion and contraction as the roof structure heats and cools throughout daily solar cycles. Butyl tape is engineered to remain continuously compressed and protected within a joint to maintain a watertight seal. However, solar heating, thermal movement, irregular substrate support, improper fastener installation, or inadequate clamping pressure can cause the butyl to soften, migrate, or extrude from the joint. Once extrusion occurs, ridge and rake details lose consistent watertight continuity.
While these visual defects did not conclusively prove that every interior drip was caused by a roof leak, they provided credible, separate potential entry paths that required empirical verification.
Complicating Factors: Deck Flutes and Spray Foam
During our investigation, water was also discovered pooling and remaining trapped within the flutes of the structural metal deck long after weather events had cleared.
The roofing contractor had previously attempted to fill portions of the deck flutes with spray foam to reduce thermal bridging. However, subsequent borescope observations indicated that the foam had failed to completely fill at least one cavity. When this foam was physically disturbed during our inspection, trapped water was immediately released.
While spray foam was not confirmed as the primary root cause of the moisture, incomplete filling obstructed natural drainage channels and retained or redirected water already present within the flutes. This mechanical obstruction helped explain why certain locations continued dripping intermittently even when it was not raining or when water testing failed to immediately reproduce a leak.
Water Testing Results and Variability
Controlled water testing conducted on the roof produced mixed results, underscoring the complexity of the building envelope:
- West Ridge Testing: Water testing directed near the west ridge reportedly resulted in approximately eight additional interior leak locations, actively supporting concerns regarding compromised ridge or flashing details in that specific zone.
- East Side Testing: Subsequent testing on the east side—performed after some roof details had been modified by the contractor—did not reproduce active leakage.
These divergent outcomes reinforced our conclusion that the building did not suffer from one uniform problem affecting the entire roof; rather, performance varied locally based on detailing execution and thermal stress.
Forensic Conclusions and Best Practices
Our final forensic evaluation concluded that the moisture issue was not exclusively a condensation problem nor exclusively an exterior roof leak—it was a combination of both:
- Condensation caused much of the widespread dripping under the original, colder interior operating conditions.
- Exterior Water Intrusion occurred via localized pathways (such as extruded butyl tape, uncompressed joint gaps, and questionable edge detailing) activated during specific rain events and confirmed during west-side water testing.
Recommended Next Steps for Facility Teams
To prevent wasted capital on premature or destructive repairs, Structura View recommended a methodical, phased protocol:
- Baseline Documentation: Record all existing interior drip locations and baseline drip rates.
- Controlled Water Testing: Test individual roof details systematically, beginning downslope and progressing incrementally toward the ridge, while the underside of the deck is continuously monitored from an interior lift.
- Selective Exploratory Openings: If water testing successfully reproduces active leakage at a specific detail, perform controlled selective openings to verify the moisture plane, trace the exact entry path, and inspect the concealed condition of the butyl tape, closures, vapor barrier, insulation layers, and deck flutes.
The Takeaway: Chasing symptoms or tearing into a roof assembly without empirical data leads to bloated budgets and unresolved risks. True building science requires looking at the entire building system—evaluating how indoor environmental dynamics, thermal performance, and exterior envelope detailing interact under real-world conditions.
