Convert unfinished attic space to a 15-by-15-foot bedroom and a 5-by-7-foot bathroom with shower. Include a 15-foot shed dormer, four new windows, and closet space under the eaves. Insulate and finish ceiling and walls. Carpet floor. Extend existing HVAC to new space; provide electrical wiring and lighting to code. Retain existing stairs, but add rail and baluster around stairwell.