In this video, after a homeowner’s bluestone patio became discolored, he called the team at Ask This Old House for help. Mason Mark McCullough has the perfect solution—literally. SUBSCRIBE to This Old House: http://bit.ly/SubscribeThisOldHouse. A backyard stone patio can be a homeowner’s dream. But when it’s surrounded by trees and shade, it can also be a dream for mold and mildew. When a homeowner faced the problem of mold and mildew taking over his patio, he called the Ask This Old House team for help. Mason Mark McCullough brought several solutions (of the cleaning variety!) to help restore that bluestone beauty. Where to find it? Using a pump sprayer [https://homedepot.sjv.io/q4Mrzg], Mark applies a multipurpose outdoor cleaner [https://homedepot.sjv.io/rQMjaD] to the bluestone and allows it to sit for a few minutes. Once the solution is set, Mark sprays down the bluestone using a power washer [https://homedepot.sjv.io/4P96P3] with a surface cleaning attachment [https://homedepot.sjv.io/Kjbk0e]. Looking for more step by step guidance on how to complete projects around the house? Join This Old House Insider to stream over 1,000 episodes commercial-free: https://bit.ly/2GPiYbH Plus, download our FREE app for full-episode streaming to your connected TV, phone or tablet: https://www.thisoldhouse.com/pages/streaming-app About Ask This Old House TV: From the makers of This Old House, America’s first and most trusted home improvement show, Ask This Old House answers the steady stream of home improvement questions asked by viewers across the United States. Covering topics from landscaping to electrical to HVAC and plumbing to painting and more. Ask This Old House features the experts from This Old House, including general contractor Tom Silva, plumbing and heating expert Richard Trethewey, landscape contractor Jenn Nawada, master carpenter Norm Abram, and host Kevin O’Connor. ASK This Old House helps you protect and preserve your greatest investment—your home. Follow This Old House: Facebook: http://bit.ly/ThisOldHouseFB Twitter: http://bit.ly/ThisOldHouseTwitter Pinterest: http://bit.ly/ThisOldHousePinterest Instagram: http://bit.ly/ThisOldHouseIG How to Clean a Bluestone Patio | Ask This Old House https://www.youtube.com/user/thisoldhouse/