A saltbox roof is a common roof type among older colonial style homes. They look very similar to a simple shed roof in that it is a lean-to, and are also similar to a gable roof in that this style creates a gable. While a gable roof has symmetrical roof fields and slopes, a saltbox roof is asymmetrical. A Saltbox roof was originally an addition that's been attached to the larger, original home. While the addition often changes its roof slope from the original roof to increase ceiling space, there are also cases where the original slope is kept through the addition. In either case there will be a sloped ceiling in the interior. These roofs became popular in early American history when colonial homes were cramped and in need of additional space. At some point these roofs no longer were built on top of additions, but became part of the original roof style as it had become so popular.
There are a few disadvantages to having a saltbox roof. They don't' allow for much attic space in the addition of the home, and they are slightly more complicated to build, although it can be made easier if the roof pitch doesn't change on the addition but instead maintains the original roof slope. The slope of a saltbox roof is generally steep enough to allow for great water runoff, keeping the roof better protected against leaks.
Pros: Good water runoff from steep pitch.
Cons: Asymmetrical shape isn't for everyone, can reduce attic space, puts a sloped ceiling in some rooms.
SALTBOX ROOF TYPE ILLUSTRATIONS