Obelisk
A tall pillar, square in cross-section, tapering upwards and with a pyramidal top.
Occasional Table
A small table that can be moved from room to room and used for different purposes.
Occupancy Permit
Issued by building authorities after the final inspection of a new home.
Occupant
Any person actually occupying and using a building or portions thereof by virtue of a lease contract with the owner or administrator or by permission or sufferance of the latter.
Occupant Load
The number of persons for which the means of egress of a building or portion of a building is designed.
Ogee
S-shaped or double curve comprising a convex and a concave section, often seen in decorative archways.
Oil-Canning
Variation from flatness of sheet metal, creating undulations along the surface. The result is poor appearance and potential ponding.
Op Art
The 1960s movement known as Optical Painting is characterized by geometrical forms that create an optical illusion in which the eye is required to blend the colours at a certain distance.
Open Space
A point at which a person exits from a building to an area outside which would allow safe passage. Egress from a building must be to a road or open space. An open space must be open to the sky and connect directly to a public road.
Open-Deck Carpark
A carpark in which all parts of the parking storeys are cross-ventilated by permanent unobstructed openings in not fewer than 2 opposite or approximately opposite sides.
Order of Architecture
The design and arrangement of a column or entablature, including the proportions of all the parts. The ancient Greek classical orders were called Doric, Ionic, and Corinthian. To these the ancient Romans added Tuscan and Composite orders. There have been countless variations on these ancient themes, eg a giant order has columns two or more storeys tall.
Organic City
A city grown from a small settlement, not built to a plan.
Oriel
A bay window suspended above ground.
Origin
The point in a drawing with the X,Y coordinates of 0,0.
Orthogonal
At right angles to, or perpendicular to.
Ottoman
A low, stuffed seat without a back, sometimes in the form of a chest; a cushioned seat for several people sitting with their backs to one another.
Outrigger
An extension of a rafter beyond the wall line.
Over Flashing
A vertical flashing dressed down a wall over an upturned apron flashing or into a gutter. Use this term instead of ” Counter Flashing”.
Overhang
Outward projecting eave-soffit area of a roof; the part of the roof that hangs out or over the outside wall.
Overlay Drawing
Drawing which is produced on a transparent medium and thus can be copied together with other drawings related to the same subject and at the same scale.
Ovoid
Egg-shaped figure or body.