We had a huge room, taking up the whole second story, with no closets. It was time to build his and her closets so we could put some actual use to the spare bedroom downstairs.
Step 1: Pick Locations For Your New Closet(s)
In our case the 2 corners were the best place to put the closets. At first we were going to put them in the 2 corners on each side of the window in hopes to create a bench area between the closets and under the window. Be sure to identify all outlets and light switches before building, in order to avoid relocating light switches we had to abort the window plan. no complaints here...
Step 2: Build Your Frame and Hang Drywall
Build the frames for your closets. I always like to take a picture of just the frame so I have an idea where the studs are. It also helps to mark some of the studs on the floor or existing walls because once you put up the drywall it all becomes a mystery.
Step 3: Dress Up the Inside of the Closet(s)
In this case "hers" is well more organized then "his." We took a trip to IKEA to buy some organizers and had to rig up some modifications to make everything fit in what's obviously a non-IKEA closet. Go all out with this and plan for everything you have.