This approximately 440 square foot plan provides two new large bedrooms and a bath in a new dormered rear. The dormer shown is 29'-4" wide and the existing home is 32'-0" wide; both could be wider or smaller. This type of shed roof dormer is adaptable to almost any existing one or one & one half story home, however, it is most suited to a home that already has a stand up attic under a steeply pitched roof. Design issues you should be concerned with, include keeping at least a small sliver of the old roof on each side; this avoids the awkward bulky looking side form so often seen on such homes. Also, consider raising the ceiling alongside the stair on the first floor to achieve a more inviting entry to both floors.