Units W/m2K—a measure of the thermal efficiency of a product expressed over the area of the opening The lower the number, the higher the insulation value.
Units W/m2K—a measure of the thermal efficiency of a product expressed over the developed surface area of the product.The lower the number, the higher the insulation value.
Automatic opening vent—a specialist type of rooflight designed for the discharge of smoke and heat. Often connected to the fire alarm system (BMS)—usually opens when alarm is activated.
A rooflight unit specifically-designed to facilitate access to the roof area – usually for maintenance.
A type of kerb that adapts a rooflight upstand to a builder’s kerb.
The lightest, most-effective translucent insulation available (see Lumiera)
Natural air seepage through unsealed voids and joints in parts of the building structure.
Roof covering material based upon a mix of asphalt and mineral fillers.
Semi-cylindrical rooflight that may be semi-circular or low rise (30° angles at kerb).
Anything below the rooflight that involves construction.
Factory-assembled polycarbonate glazing panel with either double- or triple-skins.
Electrical actuator for hinged opening rooflights.
Top face of kerb or upstand.
Vertical glazing at the base of a rooflight. Such a unit is often called a ‘Lantern Light’.
A thermal track allowing heat energy to escape by conduction.
Double glazed unit—refers to glass construction only.
The light produced by an overcast sky—averages 5,000 lux for 85% of daylight hours.
The ratio between internal and external light levels.
Property of glazing material whereby transmitted light is scattered, creating better internal light distribution and preventing direct image formation.
Rooflight shape. May refer to small moulded ‘modular’ units or large selfsupporting
glazed constructions. Can be either ‘low rise’ (usual) or ‘high rise’ (semi-circular).
May refer to ‘mono-pitch’ glazing constructed with two different angles. Sometimes used to describe a ‘ridge light’ (see Ridge Light).
Synthetic rubber used for manufacturing seals and gaskets.
Bituminous-based roof covering.
A structural member designed to support, restrain and seal glazing panels.
Bituminous based roof covering upgrade for enhanced performance and longer life
Usually refers to shape or geometry of a dome or barrel vault. Actually describes semi-circular or hemi-spherical.
Hit & Miss
A type of ventilation system. Can be either open or closed.
Rooflight set into a pitched roof so that there is no protrusion above the roof surface or plane.
Material used to increase the thermal performance of a material or system.
The roof mounting for a rooflight. May be constructed by the builder (builder’s kerb) or can be supplied as part of the rooflight. On a roof up to 17°, must protrude at least 150 mm above roof-top surface.
A rooflight set above vertical glazed sides. Invented by Victorians.
The upper, supporting frame of an opening rooflight unit.
High-spec controllable actuator for opening rooflights.
Usually refers to shape or geometry of a dome or barrel vault. Traditionally describes an arc of a circle or sphere with a 60° subtended angle.
Roof construction based upon the use of layers of corrugated metal sheets.
Single plane of sloping glazing.
Another name for a rafter—traditionally applies to windows or vertical glazing (see Rafter).
Another term for structural polycarbonate.
Trade name for Aerogel. Supplied in the UK by Xtralite Rooflights Limited.
Refers to the ability of a glazing system or rooflight to resist the impact of a stumbling, falling human body. Measured and rated to ACR[M] 001: 2005.
A sloping rooflight which faces generally in a northern direction. This limits the amount of sunlight entering the building.
A reference to a materials inability to transmit light.
Refers to Building Regulations Approved Document Part L—Subdivided into two parts each being further subdivided into two parts. Eire Building Regulations Part L—this is a reference to the section of the Eire Building Regulations intended to govern the use of fuel & energy. It is a single document with two distinct parts, Nondomestic & domestic.
Part 6—this is a reference to the section of the Scottish Building Regulations intended to cover conservation and use of energy. Part 6 is split into two parts Non-domestic & domestic.
Ventilation system that is not often used. Uncontrolled and permanently open.
A protective coating of coloured polyester or occasionally epoxy.
Usually refers to shape or geometry of a dome or glazed structure. The optimum construction angle is 30°.
A structural member designed to support, restrain and seal glazing panels. These members always run ‘top to bottom’.
Rooflight constructed with two slopes of glazing. Ends can be vertical or hipped. Can be constructed to be self-supporting.
Window specifically designed to be set and flashed into, and be flush with, a sloping tiled or, slated roof. Velux being the generic.
A roofing accessory designed to admit light into the building whilst weatherproofing the open roof aperture. Can also be used to introduce ventilation and/or gain access to the roof.
A screw or bolt with an anti-tamper head.
A rooflight structure that requires no support other than that upon which it sits.
Durable synthetic resin used as a wet sealing compound.
Designed joint making use of the properties of silicone.
Polymeric sheet roof covering.
Refers to a single leaf of glazing (usually polycarbonate) may be prefixed by single, double or triple.
Another name for a rooflight (American in origin).
Another term for an A.O.V.
Resultant internal heat gain due to transmission of solar energy.
Device for reducing the level of transmitted solar energy. May be by blinds or louvres or by selective filtration by the glazing medium.
Polycarbonate produced as monolithic sheet material similar in appearance to glass.
A type of metal decking system that joins with a rolled metal ‘zip’ system.
Self supporting system—often prefixes rooflight.
Lightweight polycarbonate sheet extruded in a multi-wall format which enhances strength and thermal performance.
A high thermal resistance barrier to heat flow. Used to insulate metal items that may run from the inside to the outside.
Plastic material shaped, when softened by heating.
Synthetic rubber used for manufacturing seals and gaskets.
A term describing the ability of a glazing medium to transmit light without being able to form an image through.
The horizontal glazing bar—runs between rafters (see transverse).
A term describing the property of a glazing medium to transmit light whilst being able to form a clear image through.
Runs across. Refers to a transom glazing bar (see Transom).
Low-level ventilation system. Usually not controlled.
The mounting for a rooflight. May be part of the roof construction or part of the rooflight itself. Must be at least 150 mm high (see Kerb).
Un-plasticised polyvinyl chloride.
Introduction of fresh air and exhaustion of stale air.
A hood shaped to shelter a detail and prevent weather ingress.
Name given to hinged opening rooflight.