Glossary

BBA
British Board of Agrément. The BBA is the UK's major approval body for new construction products and installers. BBA Agrément Certificates are recognised by specifiers and other industry decision-makers as proof that the products covered by them have been rigorously assessed, will comply with Building Regulations and will last for a defined period.

Bead
Beads clip in to the window profile to hold the double glazing units in place.

Bifold door
A contemporary door system comprising three or more large glass panes which fold back fully upon themselves to create a large opening.

BPF
British Plastics Federation. The BPF is the leading trade association of the UK plastics industry, representing 80 per cent of industry turnover.

Building Regulations
Building Regulations are Government codes which set out the criteria that new building projects and refurbishment work must conform to. The parts of the Building Regulations that apply to windows and doors include Part M, Part L and Part F. They help to ensure that buildings are safe, secure and energy efficient.

Butt hinge
A hinge that allows the full closing of a door or window. Butt hinges stand proud of the door or window surface.

Casement
The term used to describe a conventional window, with a sash that is side or top hinged. Casement windows open outwards.

Cill
Window cill. The protruding lip that directs water away from brickwork at the bottom of a window opening.

Composite door
A robust, secure style of door that looks and feels like a traditional timber door. It's made from an outer skin of GRP (Glass Reinforced Plastic) over a wooden frame infilled with foam insulation.

Co-extruded
The process of extruding a PVC-U profile and its gasket simultaneously.

Curtain walling
Glazed walling used in large buildings, often several storeys high.

Deadbolt
A secure locking system used in modern doors.

Double glazing
Glazing made up of two layers of glass with a space between them to improve insulation and reduce noise. Double glazing comes in several widths, although 24mm and 28mm are the most common.

Extrusion
Most of the profiles used in PVC-U windows, doors, conservatories and roofline are extruded. Extrusion is the process of pushing PVC-U pellets through a die to form a solid shape.

Fascia
Part of a roofline cladding system that can be fitted between the roof tiles and the brickwork to seal a house from the elements.  Fascia is the front vertical board on the complete roofline system.

French doors
Double outward-opening doors that meet in the middle without a mullion, giving a clear unobstructed opening.

French windows
Double outward opening windows that meet in the middle without a mullion, giving a clear unobstructed opening.

Gasket
The black rubber strip that runs around the pane of glass in a window to create a weatherproof join.

GRP
Glass Reinforced Plastic, also known as fibreglass. GRP is a composite material made of a plastic reinforced by fine fibres of glass. GRP is an extremely tough material used in the marine industry for its hardwearing and weatherproof characteristics. GRP is also used as the outer skin on composite doors.

Head drip
Head drip profiles feature at the top of a window or door and are a means of channelling water away from the front face of the unit.

Hook-lock
A type of door lock that throws a hook or multiple hooks into a keep when the door is locked.

Inline patio door
A sliding patio door system where the moving door pane slides in front of the fixed pane.

Injection moulding
The manufacturing technique used to make parts from both thermoplastic and thermosetting plastic materials in production. Molten plastic is injected at high pressure into a mould, which is the inverse of the product's shape. Moulds are made from either steel or aluminium and are precision-machined to create the features of the desired part.

ISO
The International Organisation for Standardisation (ISO) is an international standard-setting body composed of representatives from various national standards organisations. ISO sets standards for manufacturing and environmental processes.

Low 'e' glass
Low 'e' stands for low emissivity glass. This glass varies from normal clear glass in that one side has a special metal coating, technically known as a low emissivity coating. Low 'e' glass is a type of insulating glass which works by letting in energy from the sun while blocking heat loss from the home.

Mainframe
The section of PVC-U profile used to construct the outer frame of a window.

Mullion
A mullion is the vertical structural element which divides adjacent window units.

Outer frame
An alternative term for the main frame of a window system.

Part M
Access to and use of Buildings - Building Regulations. Part M stipulates parameters for the width of front doors and the height of door thresholds, ensuring that people with reduced mobility can easily access buildings. Synseal Part M compliant thresholds have been designed to offer easy wheelchair access.

Part L
Conservation of Fuel and Power - Building Regulations. Part L sets the thermal efficiency standards that buildings must comply with. All windows must now meet the standards set out in Part L.

Part F
Ventilation - Building Regulations. Part F sets out how much ventilation a building must have. Its impact on windows is often the addition of trickle vents.

PAS 23/24
PAS 23 - General performance of doors / PAS 24 - Enhanced security. PAS23/24 are accreditations that test the performance and security of doors.

PVC-U
Polyvinyl Chloride - Unplasticised. The rigid plastic used to manufacture Synseal windows and door profiles. PVC-U provides low maintenance coupled with long life. The term PVC-U is often misunderstood. Mis-spellings include PVC, PVC-U, U-PVC, UPVC, PVCu and uPVC. PVC-U is sometimes also referred to as just plastic, e.g. plastic windows.

Sash
The opening portion of a window.

Self-cleaning glass
Glass that uses a dual-action process in which organic dirt is broken down by daylight and is then washed away by rain, thus making it easier to keep clean. Pilkington Activ and St Gobain Bio-clean are leading brand names for this type of glass.

Sill
An alternative spelling of cill.

Soffit
Part of the roofline system on a house that seals the house from the elements, between the tiles and the brickwork. Soffit (sometimes called a bargeboard) is the horizontal part that runs from the fascia back to the house wall.

Transom
A transom is the horizontal structural element that divides adjacent window units.

Thermal break
A way of stopping heat or cold transfer between two surfaces (originally developed with aluminium window frames). In windows, thermal breaks are often used within the double glazed unit - see warm edge spacer.

Tilt and turn
A window system that opens inwardly in two ways. Tilt and turn windows swing completely inwards allowing for easy cleaning. They also tilt at the top to provide good ventilation without leaving the window fully open.

Trickle vent
A ventilation system built into the top of the window frame.

U-value
A measure of heat loss. The lower the U-value, the more energy efficient the window.

Vertical slider
A window in the style of a traditional vertical-sliding sash window.  Synseal's Evolve PVC-U sliding sash windows allow both the top and bottom frames to slide freely. The frames also tilt inwards for ease of cleaning.

Warm edge spacer
A new innovation that replaces the aluminium spacer. Used to separate the two panes of glass in a double-glazed unit with a spacer made of a different material (often plastic) that transmits less heat. This makes the window more energy efficient.

WER ratings
Window Energy Ratings (WERs) specified by the British Fenestration Ratings Council (BFRC) are a simple, clear and easily understandable method of informing customers about the relative energy efficiency of particular products. Windows are rated on an A to G scale, in the same way as white goods, light bulbs and other consumer products.  An A-rating indicates the most energy efficient products, a G-rating the least efficient.
Our PVC-U window and door profiles carry a 10 year guarantee.