A gambrel or gambrel roof is a usually symmetrical two-sided roof with two slopes on each side. The upper slope is positioned at a shallow angle, while the lower slope is steep. This design provides the advantages of a sloped roof while maximizing headroom inside the building's upper level and shortening what would otherwise be a tall roof, as well as reducing the span of each set of rafters. The name comes from the Medieval Latin word gamba, meaning horse's hock or leg. The term gambrel is of American origin, the older, European name being a curb roof.
Dwelling with gambrel roof in Amityville, New York, made famous by The Amityville Horror.
If the date of construction and the roof of the Henry Bull House was original to the circa 1639 date this would be the oldest known example of a gambrel in America.
Another candidate for oldest gambrel roof, said to be from 1666, Alexander Standish House
The first Harvard Hall, Harvard University, credited to be the oldest known example of a gambrel roof in North America, built c. 1677, burned 1766
A rafter is one of a series of sloped structural members such as steel beams that extend from the ridge or hip to the wall plate, downslope perimeter or eave, and that are designed to support the roof shingles, roof deck, roof covering and its associated loads. A pair of rafters is called a couple. In home construction, rafters are normally made of wood. Exposed rafters are a feature of some traditional roof styles.
Common rafters without collar beams form most of this roof. There is not always a ridge board or beam where the rafter tops meet. Under the midsections of the rafters are purlins which support the common rafters and are supported by principal rafters. This roof ends in an octagonal hip.
Rafter and tie-beam joints (Carpentry and Joinery, 1925)
