The overhang of the roof that extends beyond the walls of the house. As the purpose is to protect the walls, the depth of the eaves and the angle of them, of the roof in general, varies according to both climate and construction materials.
Soft materials – adobe, cob, straw bale require good protection from the elements, particularly from water splash, so the eaves need to be wide, but can be shallow and flat roofed. Hot climates too require deep eaves, both to protect the space inside from direct heat and intense sunlight, and to provide shade to sit beneath on the outside. Wet climates require fast run- off, so the roof, and therefore the eaves are steep and may be wide, however guttering and good soak-away facilities are the most important factors. Similarly the eaves in areas of high snowfall where snow and melting needs to be able to slide off are both steep and wide.
In temperate climates the eaves may be barely visible and as long as the guttering is good, there is no need for deliberate extension.