A gambrel is a type of roof design usually associated with the aesthetic of a barn. The general design features two symmetrical roof sides with two slopes on each side; the top slopes on either side of the structure are at a broader angle than the lower slopes, which tend to be quite steep. While the gambrel roof is most commonly associated with barns, it can be used on other structures as well, such as sheds, houses, garages, and so on. When it is used for housing, the roof may feature dormers that extend from one or more of the slopes.
The purpose of a gambrel roof is to maximize headroom and storage space within the structure while still capitalizing on the advantages of a sloped roof, including better drainage and less susceptibility to damage from the elements or debris. The upper levels of a barn were traditionally used for storage of hay or other items, so the more room that was available in the gambrel section, the more goods could be stored there. This design works well with homes, as it allows the upper level of the house to be used for living space rather than simply storage space.
The construction process involved with building a gambrel roof can take a bit more time and effort than other roof designs. The two rafters on each side of the building will be set at different angles and connected with a curb; in between the two sides of the building will be ceiling joists that provide lateral stability. A beam at the top of the highest peak will help secure all the rafters in place. An ashlaring, or a vertical piece that is situated between the lower rafter and the floor of the top level of the building, will create a flat wall surface within the structure; this piece is not always necessary, and in some barns, it is missing altogether.
One additional advantage to the gambrel roof is the overhang. The lower slopes of the roof will hang over the side of the building, adding some more protection to the walls of the structure. This is a minor feature, but an important one, as it will prevent runoff water from draining down onto the wall, potentially leading to long-term rotting and other damage to the features of the wall, including the window. Homes that feature such a design may be fitted with gutters for even more protection from the elements.