Steve Klingler and team were contacted to investigate the cause of a roof collapse in the aftermath of a storm on an older, single-story commercial property in Yuma, Arizona. The building had a low-slope, built-up-roof (BUR) assembly with a short raised parapet, which directed drainage against the front wall to drain inlets located between framed crickets.
Our first step was to collect whatever data we could to recreate the history leading up to the event, and then to inspect the roof to identify if the damage was solely the result of storm damage, or if other factors had played a part. Our visual observation revealed that the drains were blocked with debris, and other drain inlets had been added to accommodate a large deflected section located just below one of the mechanical combination fan units. A 2-inch PVC pipe had been installed in this area as a makeshift drain to take out water which apparently collected around the equipment stand. As a result of this choice by the owner to remedy the conditions with a sort of ‘band aid’ solution, water was directed to the drain inlet. The weight buildup from accumulated water could not be discharged adequately through the intended roof drains, leading to roof failure.
This failure was a result of roof assembly modifications that did not conform to common building standards and practices, along with the further offense of deferred maintenance. Had this roof received proper attention by a qualified construction specialist, appropriate maintenance and repairs would have prevented the occurrence and the resulting costly losses.
Alterations like these run the risk of sending water to areas of the roof that were not designed to accept the added load, leading ultimately and inevitably to catastrophe. No changes should be made unless performed by qualified roofing specialists, and these experts are also the proper resource to bring in annually for proper roof analysis, evaluation and repairs to insure the performance of BUR assemblies over their necessary service life and to prevent unnecessary damages like those sustained in this case.
Makeshift drain added adjacent to rooftop equipment results in roof failure
No visible break down at surfaces of roof assembly, yet the underlying roof framing failed as a result of a chronic leak through the makeshift drain