Brighton Condos at Kingston Plantation is a 500-unit luxury housing project built in 2001. A study by engineering consulting firm R.J. Kenney Associates Inc., Plainville, MA, revealed failed sealant joints and unsealed gaps around the stucco envelope's flashing and accessory points. The exterior stucco panels also had isolated hairline cracks typically found on stucco-clad buildings. R.J. Kenney recommended a comprehensive repair and weatherproofing solution that included Dow Corning® 790 Silicone Building Sealant, 795 Silicone Building Sealant and AllGuard Silicone Elastomeric Coating.
Michael Kenney, director of Technical Services for the engineering consulting firm, explained that the building's exterior envelope required extra protection because of its height and location on a beach in a hurricane zone.
"Some external systems, such as one-coat stucco, don't tolerate long exposure to water," he said. "So if you're in an area with frequent rainfall, you have to make the outer skin of the building as watertight as possible. That's why it's so important to upgrade to the best waterproofing products available, like Dow Corning silicone sealants and AllGuard."
Dow Corning Sealants: Products of ChoiceR.J. Kenney Associates and contractor Pro-Tec Finishes of Mt. Holly, NC, recommended to the condominium's owner association that 790 and 795 sealants be used to replace most of the old sealant. (The failed joints had been filled with a combination of urethane and non-Dow Corning silicone sealants.) In addition, the structure's envelope would be sealed with AllGuard coating after the joint repairs had been completed. The entire project cost an estimated $525,000 and required six months to complete with a crew of about a dozen workers.
According to Roger Koehler, project manager for Pro-Tec, there was never any question that Dow Corning products would be used for the repair.
"We have a high degree of confidence in Dow Corning products and in the Dow Corning warranty," he said. "We have worked on similar projects with R.J. Kenney and have had a very good success rate using these products."
Kenney agrees: "Dow Corning has high-quality silicone sealant products that we've had decades of experience with."
Repair Procedures and Sealants Undergo Rigorous TestingPro-Tec's repair procedures involved a three-step process.
1. Cleaning and preparation of the entire exterior surface.
2. Application of about 100 gal of Dow Corning 790 Sealant around the balconies and in stucco surface cracks. (Windows and stucco joints were re-sealed with about 300 gal of 795 sealant.)
3. Covering the building envelope with about 2,500 gal of AllGuard Coating.
Koehler explained that product selections and repair methods were decided upon after close consultation among the project's contractors, engineers and suppliers. "We try to partner with the manufacturer and get their input up front," he said. Before work began, Pro-Tec did a mock-up of the proposed repair procedures and R.J. Kenney tested it for weatherproofing effectiveness. Dow Corning products and Pro-Tec's application methods passed with solid results.
Durability of Silicone Results in Long-Term SavingsAccording to Kenney, "Dow Corning 790 displays excellent durability and bonds to porous substrates like stucco and concrete, while 795 is a great all-around sealant." He was also enthusiastic about AllGuard Coating's ability to bridge minor surface cracks. "It has greater hydrophobic properties than acrylic coatings and better color retention," he said. "The owners will also be able to avoid frequent recoating because AllGuard doesn't break down under UV light like an acrylic would." Koehler estimates that the building owners will save about $1 million in recoating costs over 20 years.
For more information on construction sealants, contact Dow Corning Corp., phone (989) 496-6000; or visit http://www.dowcorning.com .