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Philadelphia school finally gets durable deck repairs.

As only one of 176 elementary schools in the Philadelphia City School District, Richmond School must share limited resources and sometimes has to wait its turn for maintenance and repairs. However, a successful repair four years ago not only solved a stubbornly recurring problem for Richmond School, but showed how to resolve similar issues at other schools in the district. Waterproofing materials from Sherwin-Williams helped save the day.

Products Achieve High Marks Together

These products helped make an effective repair to the concrete deck at Richmond School in Philadelphia.

  • Sherwin-Williams Sher-Crete® Flexible Concrete Waterproofer provides a slip-resistant, breathable finish that protects concrete surfaces from water intrusion. Use it as a stand-alone product or an over-coat for maximum performance in high-traffic areas.
  • Sherwin-Williams Stampede-1 Polyurethane Sealant provides a waterproof and weatherproof seal for interior or exterior applications. Count on this elastomeric sealant for excellent flexibility and adhesion, allowing +/-25% joint movement capability.
  • Sherwin-Williams Stampede 2SL Polyurethane Sealant is a two-part, self-leveling elastomeric sealant for horizontal exterior applications. Designed for use on parking decks, walkways and sidewalks, it offers +/-25% joint movement flexibility.
  • H&C® Paver Sealer Natural Water-Based Clear Coat is a single-component clear coating that provides excellent weather and stain resistance while protecting against water damage.

Built in the late 1920s, Richmond Elementary has served the community well for more than 80 years. For the past few decades, however, a persistent problem had drawn unwelcome attention from city inspectors and caused frustration for the district’s maintenance crews. At the rear of the school is a concrete patio, which also forms the roof of a lower-level gymnasium and cafeteria space. Cracking in the concrete allowed water to leak through the deck, seep into the cafeteria ceiling, and cause plaster to loosen and fall. On many rainy days, students were unable to use the gym space.

Jim Moore, maintenance supervisor for the Philadelphia school system, said his crews had tried various repair methods without lasting success. “Water made its way into the deck through joints and structural cracks. We’d already tried caulking and patching the concrete wherever it was obvious that water was coming in, but before long the leakage would start up again and we’d have to do more plaster repairs,” Moore says. “This problem had been going on for at least 30 years.”

Moore’s predecessor finally approached Sherwin-Williams representative Mike Maguire for advice. Maguire investigated the problem and consulted with Sherwin-Williams national representative Larry Mroz before recommending a three-step repair process, which maintenance crews carried out during a long weekend in the summer of 2010.

On a Thursday, the crew power-washed the affected area, including the roughly 70’ x 70’ deck itself and adjacent wall areas. On Friday, they sealed cracks and joints in the concrete with Sherwin-Williams Stampede-1 Polyurethane Sealant. The crew also used Sherwin-Williams Stampede 2SL Polyurethane Sealant to fill a large expansion joint in the concrete (see sidebar). After sealing the cracks and joints, the crew allowed the sealant to cure overnight.

On Saturday, the crew applied a first coat of Sherwin-Williams Sher-Crete® Flexible Concrete Waterproofer, which had been textured and tinted to match the existing concrete color. After letting the coating cure for a full day, the crew applied a second coat of Sher-Crete on Monday, let it dry and finished with a coat of H&C® Paver Sealer Natural Water-Based Clear Coat as extra assurance of stain resistance and cleanability on the heavily trafficked deck.

“The advantage of Sher-Crete for this application is that the coating is elastomeric, so when the building or the deck moves, the products move with it rather than letting the cracks reopen,” Maguire says.

Moore says a major storm dropped more than two inches of rain just a couple of days after the work was completed, but the repair system passed that test. “There have been no more work orders for plastering in the old problem area since the repairs were made four years ago. In fact it worked so well, we’ve done the same repair to three other schools that were built to the same design as Richmond and had the same leakage problems. It makes the local residents happy to see the schools looking so good,” Moore says. And the kids are happy to have their gym space back on rainy days.