gambrel roof
n.
A two-sided roof with a double slope on each side, the lower slope having the steeper pitch.
You've seen it, I'm sure you recognize it, but did you ever know the official name of this type of roof? This style roof has been used on barns across America and the name itself comes from the Latin word gamba, meaning "horse's hock or leg." This roof style can also be seen in residential architecture, including Dutch Colonial and Shingle Styles. Originally, this style was designed to accommodate stacks of hay in countryside barns, and for residential design, it provides the advantages of a sloped roof while maximizing space in the upper level.
Here are a few Visbeen Associates' designs with gambrel roofs...
Westchester
Wellington
Winthrop
Gilda's Lakeshore Clubhouse - Conceptual Design
Sunsweet Hill
Sources:
http://en.wikipedia.org/wiki/Gambrel
http://gambrelroofs.com/