Founded in 2017, Cornerstone Companies is a luxury impact window and door dealer. Cornerstone provides custom fenestration solutions for architects and builders who create luxury, innovative residential homes. Based in West Palm Beach, FL, Cornerstone provides impact windows and doors throughout the state. The company is partnered with six major fenestration manufacturers: Brombal Group, ESWindows, Fleetwood, Kolbe, Marvin, and Oikos.