Wednesday, July 27, 2011
Moisture Control at the Cole-Digges
The Restoration Department was performing its inspection of the roofs at headquarters at the beginning of June, 2011, and discovered some significant and urgent problems. Its typical for us to have to apply either seam tape or Geocil 2315 LRF, a fibered brushable rubber sealant, to the seams of the rubber roof about every 4 years. The EPDM that was installed in 1995 is in good shape, but the seam adhesive used dries out, allowing the seams to crack and seperate. In addition to this normal maintenance, we had to repair holes gouged into the EPDM from pieces of bed frame hurled onto the Cole-Digges from the roof of the tenant house next door. We also removed a throw rug, a piece of flashing, and a toilet plunger(someone making a political statement).
The real problems were to the terne-coated, standing seam metal roof that had been applied to the 1805 section of the Cole-Digges. The roof paint was flaking badly, and the roof underneath was starting to rust. The department scrubbed the old paint off with a solution of tsp and warm water, then rinsed with copious amounts of water from a garden hose. The next day the metal was dry and clean. What little flake that was left was swept off with a broom. The seams were painted with a brush, while the flats were rolled. The primer used was Sherwin-Williams Kem-Kromik, in red oxide, and the topcoat was industrial enamel, in that same color. We used 10 gallons of each, at a cost of about$1000. I hope it lasts.
The most serious problem was at the interior gutter of the porch section. The middle front of the gutter sags, allowing ponding water. There was a two foot section of the gutter that had completely rusted out due to this ponding, but with no visible signs of damage to the porch cornice, and no indication of where the water went after it entered the leak-area. It was very curious. We finally determined that there is an EPDM rubber gutter beneath the metal gutter. Rain entered the leak hole, ran under the metal gutter, causing it to rust and leak from the underside, then re-entered the gutter at the downspout locations through the almost invisible underside leaks, and ran into the downspouts. I couldn't make this stuff up. Restoration crimped, soldered, and sealed with brushable sealant, a section of galvanized sheet metal where the ponding water occurred. The gutter bottoms were repaired using 6 inch rubber seam tape, and everything was primed and painted. The final solution for the interior gutters will be a layer of EPDM adhesed to the top of the metal gutter. Epdm is much better at handling ponding water then sheet metal. A section of downspout was also replaced at the front of the house.