Three-decker (house)

The economics of the three-decker are simple: the cost of the land, basement and roof are spread among three or six apartments, which typically have identical floor plans.

They were primarily housing for the working-class and middle-class families, often in multiple rows on narrow lots in the areas surrounding the factories.

Areas such as Dorchester, Roxbury, Mattapan, and Jamaica Plain were popular with the emerging middle class and became "streetcar suburbs" as transportation systems expanded from the older, core sections of the city.

This is one reason why three-deckers are often situated on narrow lots and are rectangular shape, with the smaller sides at the front and the rear.

This style of housing differed greatly from the well-spaced boardinghouses of the early 19th century built in Lowell and Lawrence, Massachusetts, or the cottages of Rhode Island.

[10] In smaller cities, such as Lawrence or Albany, New York, two or two and a half story variants are common, while retaining a similar overall typology, with a bay window on the front, and prominent porches.

While usually lacking the ornamentation found on other homes of the Victorian era, three-deckers were sometimes built with decorative details such as porch railings and posts.

"[3] Other common contributors to the flammability of three-deckers include primitive electrical systems such as knob-and-tube wiring, antiquated natural gas appliances such as gas-on-gas stoves, and petroleum-based shingle siding.

[15] Starting in the early 1980s, however, they became desirable again as older streetcar suburbs began to gentrify, often by buyers looking for homes where they could live in one unit and rent the other two, thus helping them pay their mortgage.