Case of the Month: Roof Damage from the Cable Installer
The claimant owned a two-story commercial building with four retail storefronts. The building was constructed of reinforced concrete and concrete masonry units with a flat roof, and was constructed circa 1929.
One of the tenants ordered cable/internet/ voice service from a major cable service provider. The cable company dispatched a technician who installed a new cable starting from the rear of the building, traveling over the roof, down the front of the building, under a front fabric canopy, and then into the front of the store. The installer fastened the cable to the walls and roof using small plastic clips with built in nails as shown below.
The problem was that many nails now penetrated the roof membrane, creating multiple locations for water leaks when the inevitable rainy weather arrived. The roof was approximately two years old. Accordingly, the claimant wanted a new roof. He claimed that, per his sources, the entire roof membrane must be removed and replaced.
GEI was assigned to inspect and photograph the site, identify and determine the predominant cause and approximate age of the observed damage, and to recommend a course of action.
Our expert inspected the site in the presence of the claimant and agreed that the integrity of the roof was indeed compromised. The sealing surface of the roof parapet was punctured by the cable clips at multiple locations along the top of the parapet.
The approximate age of the roof damage was consistent with the age of the cable installation.
As described earlier, the building had a flat roof, covered with sheet roofing material.
The margins of the roof were surmounted by a parapet wall. The roof was drained through scupper outlets to downspouts. The parapet was designed to provide a monolithic appearance from the street level, so as to hide the installation of roof mounted heating and cooling equipment. There was no evidence yet of penetration of the walls by rainwater from the parapet level. The cable was attached to the top of the eastern parapet wall by using more than twenty plastic cable clips and the cable was not fastened to the deck of the roof, which from the rear of the building to the front was a distance of approximately 110 feet.
Our expert disagreed with the opinion that the entire roof needed to be replaced. Instead he recommended that first, each of the roof penetrations by the cable clips be sealed with a polysulfide sealant. Secondly, each clip should be covered and further sealed with an approximately eight inch square of matching colored roofing material. Each sheet should extend beyond all edges of the penetrations, including sealing the edges of patches and over the cable, to once again, make the whole roof as waterproof as it was before the cable installation.
Polysulfide sealant is a long lasting, permanently flexible marine sealant. It has underwater curing capability, exceptional chemical resistance, high dielectric strength, high physical strength, and is resistant to vibration, impact, shock, and thermal cycling.
The recommended repair prevented future rainwater damage from the cable clips and saved many thousands of dollars by avoiding the needless replacement of the two year old roof.