Window Restoration Glossary

Annealed glass

Annealed glass is standard, untreated float glass that has been cooled slowly in a controlled process (annealing) to relieve internal […]

Accoya® wood

Accoya® wood stands as a top-quality timber product which comes from sustainable sources and undergoes acetylation to improve its natural […]

Awning windows

An outward swinging window unit opening from the bottom and hinged at the top. Benefits of this window style include […]

Bay window

A bay window is a building element which projects from exterior walls by extending outward into space. The typical design […]

Bow sash window

The bow sash (or bow-faced sash) is a unique and particularly attractive form of sash window. Existing in a few […]

Casement Window

A casement window functions as a window which has its hinge on one side to allow it to swing open […]

Conservation area

A Conservation Area represents a special designation which local planning authorities in the UK assign to areas that show exceptional […]

Conservation Glazing

Conservation Glazing refers to high-performance window upgrades—such as slimline double glazing or vacuum insulated glazing (VIG)—specifically designed for use in […]

Draught-Proofing

Draught-proofing (sash windows) involves sealing the moving sash gaps to stop cold air from entering while enhancing heat retention and […]

Double glazing

Double glazing is a window construction method which employs two glass panes that remain separated by a sealed air or […]

Dormer window

Dormer windows are instantly recognisable features of much historic European architecture and describe a window set into a sloping roof. […]

Fixed sashes

Fixed sashes are non-opening window units—typically timber-framed panels with glazing—that are permanently sealed within a window frame or bay. The […]

Glazing bar

A glazing bar serves as a horizontal or vertical bar which functions structurally or decoratively to divide window sashes into […]

Georgian sash

Georgian sash windows are characterised by their elegant, symmetrical design and multi-pane glazing—most iconically in a six-over-six configuration (six panes […]

Listed building

The United Kingdom protects special architectural and historic structures through formal recognition as Listed buildings which receive legal protection. The […]

Low-E glass

Low-E (low-emissivity) glass contains a thin metal coating which allows sunlight to enter but bounces heat back into the room. […]

Microporous paint

Microporous paint functions as a high-performing breathable coating which developers designed to protect exterior timber surfaces including windows and doors […]

Putty glazing

Putty glazing is the traditional method of securing glass panes into timber window frames using linseed oil-based putty (often called […]

Part Q compliance

Part L compliance refers to meeting Part L of the UK Building Regulations — “Conservation of Fuel and Power” — […]

Part Q compliance

Part Q compliance refers to adherence to Part Q of the UK Building Regulations – “Security: Dwellings” -which sets minimum […]

Sash cords

Sash cords are the braided cotton or synthetic ropes traditionally used in counterbalanced sash windows to connect the moving sash […]

U-value

U-value measures how effectively a window resists heat transfer—the lower the U-value, the better the insulation. Expressed in W/m²K (watts […]

Vacuum Insulated Glazing (VIG)

Vacuum Insulated Glazing (VIG) is an advanced, ultra-thin double-glazing solution ideal for historic and period properties. The VIG system employs […]

Weight-and-pulley system

A weight-and-pulley system serves as the basic counterbalance mechanism which operates box sash windows. The system contains cast-iron or lead […]

Xenon

Inert, nontoxic gas. Xenon occasionally appears in high-performance insulating glazing units (IGUs) as a substitute for argon or krypton but […]