With an extra legal bedroom, you could recover 10 to 20 times your window installation costs when you eventually sell your home. Local regulations vary, so you'll need to start with a visit to your codes administration office. And if it has occurred to you to call a given room a den before the inspection and a bedroom after, well, let's just say that this isn't a very original idea. Today, any bedroom-sized room with a closet is considered a bedroom, no matter what the blueprint says. As for size requirements, expect to need a window with an opening of 5.7 sq.
Some codes count the glass area, while others measure the area with the window open.
In any case, a vertical casement window with 6 sq. The height of the window installation is also important. The bottom of the window opening should be no more than 44 in. off the floor. Outside, an oversize window well is required. It will need to be at least 36 in.