October 26, 2017

U – W

U – W



Window supplied ex-factory without glass.

Term normally used to refer to one single assembly of an Insulating Glass Unit (IGU).

Unplasticised polyvinyl chloride, a rigid structural plastic which resists degradation under ultraviolet radiation; used for window frames and other building components. Same as PVC-u (European usage) and vinyl (North American usage).


Visible Face
Applies to extrusions and describes the visible area remaining on the section when the section is assembled into a window.

Visual Comfort
Refers to a set of qualities associated with the amenity of a window, such as freedom from glare and excessive contrast.

Polyvinyl chloride material which can be either rigid or flexible, used for window frames.


Water Penetration
A term used to describe the water performance of a window. Part of the standard testing procedure on a window calls for a water test.

A window shall not have water penetrate beyond the inner face after a 15 minute water test at a specified wind pressure. Minimum pressure is 150 Pa up to a maximum of 450 Pa.

Weather Flange
The portion of a section which acts as a weather barrier between opening sash and frame.

Weather Flap
A flap system within the sill of the window designed to allow water to escape and to prevent wind blowing directly back through the drain slots. Not to be confused with an under sill flap which fits under the window sill to allow for building settlement.

Weather Seal
A material included in a window assembly to reduce the air infiltration or improve resistance to water penetration.

Weather Strip
Thin sections of compressible material used to prevent air leakage around operable windows and doors.

Wood (or metal) wedges used to secure the window or door unit in the rough opening in a plumb, level and square position during and after installation.

Weep Holes
(See also Drainage Slots) Drain holes or slots in sash or framing member to prevent accumulation of condensation and water.

Wind Load
The wind pressure in Pascals that the window has to meet. Wind load varies according to location and exposure.

Window Assembly
A complete unit comprising frame, couplings, sashes, glazing infill panels and hardware.

Window Dimension
The window frame size as shown on a brochure. Size is to overall frame size, not to overall reveal fin size. (H) refers  to window height (W) refers  to window width

Window Hardware
Various devices and mechanisms for the window including catches, fasteners and locks, hinges, pivots, lifts and pulls, pulleys and sash weights, sash balances and stays.

Window Labelling
Concept of implementation of standards and ratings for energy performance, weather-tightness, structural, acoustic and safety issues for window products.

Window Mould
Another way of saying Storm Mould.

Window Rating
(See also Rating)

Window Wall
A series of multi-light windows, generally from floor to ceiling and often continuous horizontally.