Saltbox house

A saltbox house is a traditional New England style of house with a long, pitched roof that slopes down to the back, generally a wooden frame house. A saltbox has just one story in the back and two stories in the front. The flat front and central chimney are recognizable features, but the asymmetry of the unequal sides and the long, low rear roof line are the most distinctive features of a saltbox, which takes its name from its resemblance to a wooden lidded box in which salt was once kept.

Origins
The saltbox originated in New England, and is an example of American colonial architecture. Folklore holds that the saltbox form was popularized by Queen Anne’s taxation of houses greater than one story. Since the rear of the roof descended to the height of a single-story building, the structure was exempt from the tax. Actually, the saltbox shape evolved organically from the need for additional space for growing families; adding a lean-to was an economical way to enlarge the house. All but two of the examples below predate Queen Anne.

The roof style is also known as a catslide roof, any roof that, on one side, extends down below the main eave height providing greater area under the roof without an increase in the ridge height.

The earliest saltbox houses were created when a lean-to addition was added onto the rear of the original house extending the roof line sometimes to less than six feet from ground level. Old weathered clapboards are still in place on parts of the original rear exterior walls of some of the earliest New England saltbox houses (see images). The hand-riven oak clapboards on both the Comfort Starr House and Ephraim Hawley House are preserved in place in the attic that was created when the lean-to was added onto the original house. The style was popular for structures throughout the colonial period and into the early Republic, perhaps because of the simplicity of its design.

Ephraim Hawley House, Nichols, Connecticut catslide rear roof

Ephraim Hawley House, Nichols, Connecticut original oak clapboards in leanto attic
Saltbox homes can also be found in parts of Newfoundland and Labrador.

Construction
Most early saltboxes, as with many other types of New England colonial houses, are timber-frame. Timber framing, or post-and-beam construction, involves joining large pieces of wood with woodworking joints, such as mortise-and-tenon joints, or with wooden pegs, braces, or trusses. Metal nails were sparingly used. The exterior of a saltbox was often finished with clapboard or other wooden siding. The Josiah Day House in West Springfield, Massachusetts is constructed of brick.

Source From Wikipedia