Eaves:

The bottom edge of a sloping roof or the outer edge of a flat roof, often projecting out beyond the face of the wall.

Elevation:

Another term for the particular view of a building from a certain direction, e.g. south elevation, or front elevation.

Expansion joint (or movement joint):

A joint built into a wall or other structure designed to prevent cracking caused by thermal movement.

Expansion tank:

A small water tank located at the top of a building which receives excess hot water from a system resulting from thermal expansion.