A stacking washer and dryer is probably the most desirable master closet amenity you can add. Compact units require a space about 40 inches deep and 32 inches wide.
You’ll also need dedicated electrical outlets, hot and cold water supply, and a waste line, plus a few extra feet of countertop for folding, all of which can add $800-$2,500 (not including the washer and dryer) to the job cost.
A master closet dressing room needs plenty of light, but the classic bare bulb with a pull cord won’t meet today’s electrical codes. Code-compliant recessed ceiling fixtures can be positioned to eliminate shadows. Install multiple fixtures to provide good overall lighting without diminishing head room or style. Expect to pay from $20-$150 per fixture, plus $50-$200 per light for installation.
You’ll want air circulating in the master closet to help expel moisture and odors that come in on clothes and footwear. But unless the exterior architecture of your house demands it, avoid windows in your walk-in. Sunlight can fade colors and degrade fabric.
Instead, include one or more heating and cooling vents to help circulate the air. If that’s not possible, you can install a simple exhaust fan, much like what’s in your bathroom, to suck stale air from the master closet and expel it outdoors. Expect to pay $70-$300 for an exhaust fan, plus $30-$70 for an hour-long installation.