Lean-to

A lean-to is a type of simple structure originally added to an existing building with the rafters "leaning" against another wall. Free standing lean-to structures are generally used as shelters. One traditional type of lean-to is known by its Finnish name laavu.

Lean-to buildings

A lean-to is originally defined as a building in which the rafters lean against another building or wall, a penthouse.

A lean-to shelter is a free standing structure with only three walls and a single-pitched roof. The open side is commonly oriented away from the prevailing winds and rains. Often it is a rough structure made of logs or unfinished wood and used as a camping shelter. Temporary structures made from wood or textiles are also termed lean-to's if constructed with a single slope of the roof. In some cases the sloping roof extends all the way to the ground thus the roof itself forms the rear "wall".

A lean-to addition is a shed with a sloping roof and three walls that abuts the wall of another structure. This form of lean-to is generally provisional; it is an appendix to an existing building constructed to fulfill a new need. Sometimes they cover external staircases, as is the case with the lean-to building built in the 15th century against one of the walls of the large chapter room of the cathedral of Meaux. Sometimes, they are built to protect entrances or to establish covered markets around certain large civic buildings.