Glossary of glazing terms
With a passion for providing impeccable customer service that’s matched by the quality of our high-performance windows and doors, we’re driven to help our customers understand all there is to know about our aluminium, timber and composite window and door systems.
To that end, we have put together a comprehensive glossary of glazing terminology that we may use to describe to you our products and processesAnchor
- Acoustic insulation
Minimising the ratio of external noise passing its way through a glazed surface.
- Annealed glass
A manufacturing process, designed to release any internal stresses from glass panes to ensure further processing of the glass post-manufacture.
- Argon gas
An inert gas that’s used to fill cavities within double-glazed low-emissivity units for improved thermal efficiency.
A glazing treatment designed to minimise light reflectance and show almost no visual reflection whatsoever.
- Aspect ratio
The ratio of the longer side of a glass pane in relation to its shorter side.
The glass manufacture process to create a glass edge that’s finished at a bevel angle.
Legislation surrounding building control as specified by Acts of Parliament.
A set of best practice standards for UK-based and many Ireland-based manufacturers to adhere to.
A spacer bar is normally positioned between two panes of glass in a double-glazed unit, creating a cavity that’s often filled with air. However, it can also be filled with argon for enhanced thermal qualities.
Arguably the most popular window design in the UK that’s attached to its frame by two or more hinges.
A material that’s applied on top of a window or door frame to prevent any elements of the weather from passing through it. At Livingwood, we sell aluminium-clad glazing.
An extremely thin, usually aluminium-framed wall that’s non-load bearing and filled with glass panes to become an integral part of a building’s envelope.
The process by which gas or vapour transforms into liquid via cooling.
- Double glazing
A glazed product featuring two panes of glass for thermal and/or acoustic insulation.
A drying agent regularly used in the process of manufacturing insulating glass units.
Glass panes that have been pre-drilled ready for fixing and fitting as part of the final manufacture process.
Relates to windows with two movable sashes which operate vertically.
The surface characteristic of a material, such as glass or aluminium. If a surface is capable of absorbing and emitting energy via radiation it is considered to be low-emissivity, largely thanks to coatings applied to minimise the normal emissivity of standard glass panes.
The amount of solar energy absorbed and re-emitted externally and inside a property by a glass pane.
The amount of solar energy flow transferred straight through a glass pane.
A product made by the manufacture process of extruding. This includes the aluminium cladding used on the exterior of clad window and door systems.
The front or ‘face’ of a building.
Also known as a glass mullion, a fin is a vertical glass support to stand between two abutting panes of glass.
An industry term used to describe the positioning and installation of a window in any type of building.
- Fire resistant glass
A glazing specification capable of providing an effective barrier against the passage of toxic gases, smoke and subsequent flames; whilst minimising transmittance of radiated heat.
Occurs when moist air comes into contact with cooler drier air, also known as condensation.
- Glazing bead
A strip of material – usually metal or wood – used to meet the glazing surround with the fixed position of the glass.
- Glazing tape
Used to install glass and double-glazed glass units into timber and steel-framed window and door systems.
Relates to the solar factor of a glass pane, according to EN 410. Previously shortened to SF or TT.
- Heat-formed glass
Glass panes which have been formed at the highest possible temperatures, sometimes to create aesthetic effects.
- Heat-strengthened glass
Glass panes which have been treated to develop a structural resistance to thermal damage. With fracture characteristics akin to that of annealed glass it cannot however be known or used as safety glass.
Terminology used to describe the operation of a window or door i.e. left or right-handed.
- Heat soak test
An additional glass treatment designed to further improve the structural integrity of panes after heat strengthening, reducing the threat of unprompted breakages.
- Inner pane
The closest glass pane to a building’s interior within a double or triple glazed unit.
- Insulating glass
Two panes of glass separated by a spacer and sealed hermetically with dead air or gas-filled space between the panes.
- Inner pane
The capabilities of a glass pane to retain its structure in the face of the elements and provide a barrier to severe heat and flames, for instance.
The material positioned between glass leaves as part of the laminating process. It is typically a resin, PVB or intumescent material.
The previous name used in the European industry to describe U-values.
- Krypton gas
An inert gas commonly used to fill small air spaces between glass panes, known as cavities, resulting in improved year-round thermal performance.
- Laminated glass
The process of laminating two or more sheets of annealed or heat-treated glass, separated by at least one PVB interlayer. The end result is a dependable adhesion between the elements and enhanced security and safety for glazed products.
- Lacquered glass
The process of depositing and baking highly resistant lacquer onto a specific side of a glass pane to create opaque or coloured glass specifications.
- Light reflectance
The amount of light within the visible spectrum that’s reflected by glass panes.
- Light transmittance
The amount of light within the visible spectrum that’s transmitted internally by glass panes.
The overarching term used to describe a load exerted onto a structure or elements of it, e.g. wind loads.
- Low-emissivity glass
A glass specification designed to improve thermal performance by blocking a greater percentage of long-wage radiation. Low-emissivity, or Low-E, glass is coated with a thin metal or metallic oxide layer to supress radiative heat flow.
The vertical framing section or support between glass panes.
- Multi-point locking system
A combination of standard multiple point locking mechanisms designed to offer improved security and performance for door and window systems.
- Non-insulating glass
Typically single pane fire-resistant glass.
- Obscure glass
Most commonly used in living areas requiring privacy, obscure glazing is created by running molten glass through specialist rollers, patterning the glass to obscure views both externally and internally.
- Obscure glass
- Outer pane
The closest glass pane to a building’s exterior within a double or triple glazed unit.
Glass panes which have been made wholly non-transparent by being painted or fully enamelled on either side.
- Patent glazing
A type of glazing system, used typically in overhead glazing, that is non-load bearing.
- Patterned glass
A textured glazing specification created by specialist rollers onto molten glass, embossing a specific pattern on one side of the pane whilst keeping the other side smooth.
- Polyvinyl Butryral (PVB)
The plastic interlayer used between glass leaves in the process of laminating glass to provide the best possible adhesion of materials and subsequently enhance its safety characteristics.
- Photovoltaic glass
A specialist glass specification featuring integrated solar cells, designed to convert absorbed solar energy into electricity.
The level of resistance any material has to heat flow. The higher the number the better its insulating properties.
The trimming of the first compound application used to seal glass panes prior to the use of additional sealants.
The area of the glass framework which forms an angle into which the glass is positioned and held in place.
- Resin laminate
Resin interlayers can be used in the lamination process of two or more panes of glass, in the same way as plastic (PVB) interlayers.
- Reflective coating
The metallic or metal oxide coating used to increase the percentage of light and heat reflected by glass panes.
- Safety glass
Glass can only be labelled safety glass once it has passed a British Standards impact test (BS 6206: 1981) and must not break or be capable of breaking safely.
- Self-cleaning glass
A glass specification designed to break down organic dirt and reduce the adherence of mineral materials over time. A photocatalytic and hydrophilic coating is applied to help glass panes stay cleaner and clearer for longer.
- Sight line
The perimeter of the opening that admits daylight into living and work areas.
- Silicone seal
Silicone seals are used to fill edges of double-glazed units that are unframed and subsequently exposed to direct sunlight, improving their resistance to UV rays.
- Solar control glass
A glass specification designed to prevent excessive heat gain for interiors. Panes are coated with a microscopically-thin material to absorb and reflect solar energy.
- Solar heat gain
The amount of heat radiated into interiors via a glazed surface. Read more about Heat Loss & Heat Gain here
- Spacer bar
These are positioned along all edges of double-glazed units, separating the two panes of glass to create a cavity.
- Sound reduction index
A measure of a material’s sound insulating properties within a specific frequency band. Read more about Sound Reduction Index here
- Textured glass
See patterned glass.
- Thermally toughened glass
Glass panes which have been exposed to a controlled cooling and heating process, with the aim of improving its resistance to mechanical and thermal stress, subsequently enhancing its safe-breakage characteristics.
- Textured glass
- Thermal break
An area between the inner and outer parts of a glass frame filled with an isolating material of low thermal conductivity to minimise the rate of external heat loss via the frame.
- Tinted interlayer
A coloured sheet of resin or plastic that binds together two or more panes of glass.
- Total transmittance
The amount of solar radiant heat energy transmitted via glass panes, usually attributed in a percentage.
The measure of the rate of heat loss via a building component, such as a window or door system. U-values are normally expressed as W/m²K.
- UV transmittance
The total percentage of solar energy transmitted by glass panes in the form of UV radiation.
- Uniformly distributed load
Pressures exerted evenly across a glass pane, e.g. wind load.
- Vertical glazing
Glazed structures that are either true vertical or within 15-degrees either side of true vertical.
- Vision area
The area of a glazed pane which allows an individual to view externally from the interior.
The concept of minimising the heat conductive capabilities of double-glazed frameworks by replacing conventional aluminium cavity spacebars with thermally insulating cavity spacers.
- Wind load
The positive or negative force on an external area of a building directly resulting from wind. Typically expressed as N/m².
- Window Energy Rating (WER)
A programme led by the British Fenestration Rating Council (BFRC), designed to review the whole energy performance of a window, including all of its components.
Hermetically-sealed windows or doors to prevent the entry of water and air into structures.
Now that our doors are installed, I thought I should go on record by saying how much we appreciate having them and how much they are admired by all who see them. We are grateful to you and your colleagues for giving us such prompt service and for making the whole experience so easy and striaghtforward. The advice and suggestions you made in the initial stages probably prevented us from making mistakes in our choices. Your follow-up service in dealing with minor snagging is also appreciated. We would not hesitate to recommend you to other people.