Over the last few years, outdoor spaces have gone from overlooked to essential living areas. As a result, building a patio or deck in your backyard is one of the best home renovations you can do to increase your home's value. Patios are on the cheaper end, costing as little as $15 per square foot, while decks can cost between $6,000 and $20,000 in all, depending on materials, size, and features.