Our project in Chelsea began with the demolition of the parapet wall at the roof level. The portion of the roof being replaced served as rainwater and snow catchment for the larger, slightly raised slopped roof. The owner was concerned about the drainage and watertighness of this portion of the roof. It was observed that the apartment on the top floor had wall in the kitchen where the paint was peeling and cracking. This was happening in the corner of the ceiling directly underneath the area of the roof where all the water drained off into the downspout. The existing roofing material had become insufficient at retaining water and now allowed moisture to penetrate the interior surfaces.
After the scaffolding was setup, the old terracotta parapet caps were removed. Then the existing wall was dismantled until it was flush with the roof plane. The masonry specialists then installed new courses of brick which created the new parapet.
To solve the drainage problem the masons created a square 8″ drainage cavity that the roofers could then line with EPDM Rubber Roofing. EPDM (ethylene propylene diene monomer (M-class) rubber) has an average lifetime of 20 years! The existing tar-applied roofing paper, however, only lasts 8 -12 years. Once a roofing material has allowed moisture into the interior that means it has failed. The second part of the drainage problem was that the vent pipe (plumbing exhaust apparatus) was too close to the drainage area. So we had a section cut out of the roof around the pipe which allowed the plumbing specialist to attach an elbow pipe fitting to the existing vent pipe. This gesture moved the exit of the pipe back from the roof drainage area about 1′-3″. This was enough space to prevent snow,debris, and water from clogging the drain area.
After the vent pipe is secured in place, the roofers quickly pinned down large sheets of foam roofing insulation. The insulation was then covered the with EPDM rubber material mentioned previously and capped around the edges with a narrow strip of metal flashing.
There were three different subcontractors involved in the job; plumbers, brick masons and roofers. The final phases of the roofing work all happened simultaneously. The roofing work finally ended with brand new terracotta parapet capstones being installed and the exterior courses of brick being painted to their original color.