Cavity Wall
A common wall construction in the post-war period but rare at earlier times. It comprises two layers of (usually) brick and sometimes concrete block with a gap (cavity) between them to restrict dampness and improve insulation.

Ceiling Joist
A wood or steel beam which carries the ceiling beneath it.

Damp Proof Course
A horizontal layer of impervious material laid in a wall to exclude water usually at 6" (15 cm) above ground level. A damp proof course subsequently installed in an older property will usually take the form of a series of chemical injections into the brickwork.

Damp Proof Membrane
An impervious layer under a concrete floor or similar designed to exclude water.

Eaves
The lowest overhanging part of a roof.

Flashing
A strip of lead, zinc or other impervious material which excludes water form the junction between a roof covering and another (usually vertical) surface such as a chimney stack or parapet.

Hip
The outstanding edge formed by the meeting of two roof surfaces.

Floor Joist
A wood or steel beam which directly supports a floor.

Joist
See Floor Joist or Ceiling Joist.

Parapet
A low wall which projects above a roof surface, sometimes at the edge of it and sometimes marking the line of junction between two properties.

Party Structure (Party Wall, Party Chimney Stack, Party Parapet etc)
Any such structure which is built on the line of junction of two properties and where ownership is shared between the two adjoining property owners.

Purlin
The main horizontal beam in a roof which supports the common rafters and ultimately the roof surface.

Rafter
A sloping timber extending from the eaves to the ridge of the roof.

Rainwater Gutter
A channel along the edge of a roof to collect rainwater.

Rainwater Pipe
A pipe which takes rainwater from a roof or gutter.

Ridge
The apex of a roof, usually a horizontal line.

Sleeper Wall
A wall under the wooden ground floor of a house with no basement supporting the floor joists usually with a few bricks omitted for ventilation.

Solid Wall
A wall of any masonry material (but usually brick or concrete block) which consists of a single layer of brickwork (of any thickness) and which does not have a cavity.

Valley Gutter
The intersection between two sloping surfaces of a roof towards which water flows - the opposite of a hip.

Wall Tie
The connecting piece between the two layers of a cavity wall installed at intervals.

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