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Finding the Leak

Like the bumper sticker says, Leaks Happen. Eventually all roofs will leak. The various available condo roof surfaces typically have different reserve fund plan expected useful lives. High slope roofs such as fiberglass composite shingles are budgeted to be replaced in 25 to 30 years while low slope roofs surfaces such as EPDM (black) or PVC and TPO (white) roof membranes are expected to last 20 to 25 years. Of course, there are variables to consider such as frequency of inspection, repair history, and quality of original workmanship, but for planning purposes the industry standards can be relied on. What is difficult to predict is when the roof will leak or finding the source of the leak when it starts.

Repairing the leak usually starts with the water intrusion becoming noticeable to a unit owner who reports the problem to the property manager or building committee. Sometimes the source of the leak is obvious as is the repair plan. Unfortunately, this is rarely the case. Instead, the search for moisture infiltration can be a challenge with various investigative steps eliminating what is not the source. First, the possibility of an interior leaks must be eliminated. This could include leaky plumbing pipes; HVAC equipment condensation; fire sprinkler system; hot water tank leak; and ice dams.

Depending on whether the building has a high-slope or low-slope roof, the next steps often include viewing the underside of the roof either from an attic space or mechanical room with a flashlight. Luckily, the point of water infiltration can easily be spotted from visible water staining on the roof sheathing or decking underside and water or pooling marks on the floor. Following the interior investigation, viewing the roof surface directly from the ground with binoculars or walking the low-slope roof surface. Looking for damage or missing shingles or other roof components can be successful while inspection of roof membrane surfaces focus will be on broken membrane seams, holes, or flashing damage. If this visible inspection comes up empty, a more proactive effort may be required including spraying the roof surface area with water to repeat the leak occurrence or even flooding the low-slope roof area. Beyond this preliminary effort, my recommendation is to seek professional help.

This help should start with pulling out the original roof warranty (assuming you can find it) and read it to see if it would apply and then act accordingly. Your next step could be to call your local roofing contractor. Many of these roofing companies are very good but their business model is based on installing new roofing surfaces not your less rewarding repair service needs. This approach also faces the concern of conflict of interest following the roofing contractor’s inspection report recommending your condominium needs the entire roof surface to be replaced, not repaired. At this point, you may want to consider calling the engineering firm who recently performed your condo’s reserve fund study for guidance. The phone call will be free of initial costs, and should you engage their technical services their opinion will be free of conflicting bias while potentially making available to you technical and forensic tools you did not know existed.

Source of Moisture

As was suggested, fixing the leak is the easy part. Finding the leak is the challenge. As an example, a property manager for a low-rise condo community with flat roofs called me to tell of a water leak in a unit owner’s top floor kitchen ceiling where water was dripping from the ceiling light fixture. Above the ceiling was a dead plenum space containing the structural roof framing joists and utility cable conduits. The maintenance staff cut an access hole in the kitchen ceiling to view the underside of the roof steel decking and inspected the EPDM roof membrane surface above but with no success in finding the source of the leak. When I arrived what I found would have made Rube Goldberg proud of this leak.

Using an infrared thermal scanner, I followed the trail of the leak in reverse. The water source was a pool of water forming in a low area of the drywall ceiling’s vapor barrier where a pin hole in the plastic allowed water to find its way to the ceiling light fixture’s penetration hole. This pool of water was caused by the dripping of water from the above suspended metal cable tray channel which had a small hole caused by a missing fastener screw. This cable tray channel went 15 feet to the left till it was located under a structural steel frame for the HVAC unit located on the roof. Water dripping from the lower flange of this structural I-beam was coming from water falling from the upper flange of the I-beam four feet up-slope that was being wetted by water falling from an equipment mounting bracket bolt whose vibrations caused the EPDM membrane covering it to be cut allowing rainwater to enter the building. The use of infrared thermography allowed me to follow the differential surface temperature along the leak path right to the source.

Flashlights and moisture meters are still very useful but new effective forensic tools have become available for investigating moisture damage to structures including both thermal and infrared imaging; hygrometric scanning; capacidence testing; water vector mapping; electrical potential difference (ELD) testing; and nuclear scans. The use of low flying drones equipped with infrared scanning cameras for inspecting expansive flat roof surfaces is now readily available. There is no greater danger to buildings and their occupants than unauthorized water.

Written by Jack Carr, P.E., R.S., LEED-AP, Senior Consultant Criterium Engineers
Published in Condo Media