building terms o



OBELISK

A four sided shaft of stone, usually monolithic, tapering as it rises, and terminating in a pyramid at the apex.


OFF FORM CONCRETE

Concrete which is formed by placing and stripping from formwork and has no other applied finish.


OFFSET

An effect produced when a material deviates from the face of the work below.


OGEE

A mounding, wave-like in section, i.e., partly a hollow and partly a round.


ON CENTRE

The distance from the centre of one structural member to the centre of a corresponding member (e.g. the spacing of studding, girders, joists, or other structural members). Same as centre to centre.


ONE-PIPE SYSTEM

Waste and soil water flowing down the same pipe, and all the branches connected to the same anti-siphonage pipe.


OPEN NEWEL STAIR

A stairway using two landings, with a short flight of steps between them, and newel posts at theangles. Also called hollow newel stair.


OPEN-PLANNING

The designing of a building with few fixed partitions.


OPEN STAIRS

Stairs which have no risers.


OPEN STAIRWAY

Stairway with one or both sides open to a room. A balustrade or handrail is commonly used on the open side or sides.


OPEN STRING STAIRS

Stairs which are so constructed that the ends of the treads are visible from the side.


OPEN WELL STAIR

A stairway of two or more flights enclosing a clear, vertical space Between the outer sides of the flights.


OPENWIRING

Wiring which is not concealed.


OPENWORK

Construction which shows openings through the substance of which the surface is formed.


ORIEL

Part of an upper room projecting from the outer face of a wall, supported by brackets or corbels, and containing a window.


ORIENTATION

The siting of a building in relation to prevailing weather, air movement, sun exposure and outlook.


ORIFICE

A small opening or mouthlike aperture in a material.


ORTHOGRAPHIC PROJECTION

A drawing of the various views or sections of a building, so the projecting lines are perpendicular to the plane of projection.


OUTER STRING

In a staircase, the string farthest from the wall.


OUTLET

An opening serving to direct the discharge of a liquid or service (e.g. electric power, stormwater).


OUTLET BOX

An plastic box placed at the end of a conduit system where electric wires are joined to one another and to the fixtures.


OUTLETS, Grouping of

The connecting of several electrical outlets on a final sub-circuit.


OUTSIDE FOUNDATION LINE

A line which indicates the location of the outside of the foundation wall for a new building.


OVERFLASHING

The flashing which is built into the wall surface and sits over the upturned apron flashing.


OVERFLOW PIPE

A pipe or emergency outlet provided to carry off excess water from a tank.


OVERHANG, Roof

The section of a roof extending over the external wall. (See EAVES.)


OVERLOADING

Placing too heavy a load on a beam, column, or floor.


OVOLO

A reentrant moulding of convex quadrant section.


OYLET

A small hole or perforation, an eyelet.





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