Stacked washer and dryer sets are available at Home Depot, Best Buy and Sears, as of 2015. The units are sold with a choice of an electric or gas dryer, and most sets require an exterior vent for the dryer.
Stacked washer and dryer sets usually have a smaller capacity than stand-alone units, and they offer fewer wash cycles. The advantage of a stacked unit is that its narrow size allows for placement in tight spaces. Dimensions vary by model, but some units are just 24 inches wide, allowing them to fit inside a closet. Stacked units reach up to 6 feet high, which can make the dryer harder to access.