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Here's a glossary of the terms regularly used by doors & windows retailers, designers and installers. You may be familiar with many of these, however, this is intended to give you a useful overview for when you're ready to start speaking to your showroom consultant or installer.

Acoustic WindowsDesigned for sound protection to around 41dB. Ideal for properties near busy roads, flight paths or railway tracks
Anti-Bump and Anti-SnapLocks that don’t allow the pins in the lock to be ‘bounced’ preventing access. Anti-snap prevent the locks from snapping. They have two parts, it will lock if the front part is broken
Bubble and Flipper GasketSeals that are inserted into a recess in a window or door frame
Buy Now Pay Later FinanceAlso known as a deferred interest agreement, this tends to be the plan that causes the most confusion. With this type of plan, you tend not to start making payments for a set period, for example 12 months. Look for phrases such as “take a 12-month payment holiday” or “Buy now, pay 2021"
ChamferedThese windows have a beveled edge to them
Composite DoorComposite doors are made of different materials which are pressed and glued together under high pressure conditions including PVC, wood, insulating foam and GRP (glass reinforced plastic). The combination of materials result in a door that is very strong, secure and weather resistant. They are usually thicker than PVCu doors, 44mm as opposed to 28mm. Composite doors are about 6x more thermally efficient than a timber door
Double GlazingConsists of two glass window panes separated by a vacuum or gas filled space to reduce heat transfer
EurogrooveThis is a groove in the sash or door panel. It allows the activation of locking points in the frame or sash
Fully Reversible WindowsAllows windows to be cleaned from the inside by providing 180 degree reversible opening
Georgian BarA method of diving the glass into smaller units in the window
Interest Bearing Finance DealA fixed-rate interest loan is a standard loan offered by a retailer over a set period such as 3 to 5 years with the interest fixed for the duration
Interest Free FinanceAn ‘interest free agreement’ is exactly that, an agreement where you don’t pay any interest at all, the value of the balance borrowed is divided by the number of payments or period in question, such as 6, 12, 24, 36 or even sometimes 48 months, similar to a mobile phone contract
Internally GlazedIf the window beading is fitted from the inside then it cannot be reached from the outside, therefore making the window more secure
PVC-UThe ‘PVC’ part of it stands for Polyvinyl Chloride. The ‘U’ stands for Un-plasticised. The basic material properties of PVCu make it ideal for door and window application
PVC U Thermal CoreInserting PVCu into Aluminium frames to reduce thermal heat loss
RatedRefers to the overall value of the energy efficiency of a complete glazed window or door. Ratings are coded by letters between A and G. A is the most efficient, while G is the least efficient. So, an A- rating would mean the windows don't lose energy as they only let out as much heat as they let in from the outside. However, with an A+ window, it lets in more heat than it lets out
Sash HornSmall horns traditionally added to sash windows to strengthen the frames where the central bar was removed and only one pane of glass was used in the frame
Self-Leveling RollersGive a precise, reliable and smooth sliding action to give you an ultra-smooth performance
SillThe base of a window or door
Stub SillA shorter sill that usually sits on a concrete or stone sill
Thermally BrokenA barrier is inserted between the inner and outer layer of aluminium frames to prevent thermal energy loss
Tilt and Turn WindowsDual purpose; they can be tilted and locked into place or opened inwards
Triple GlazingConsists of three glass window panes separated by a vacuum or gas filled space to reduce heat transfer. To reduce the thickness of triple glazing, inert gases such as argon or xenon are used (dehydrated air has a lower rate of thermal conduction than normal air-filled spaces). It offers ultimate thermal performance - at least 75% better than standard double glazed aluminum windows
U- ValueMeasures the heat transfer and how well the window insulates. The lower the number the less heat is transferred; therefore, lower is better


PAS24:2016This is your guarantee that the production of the door or window that you are purchasing is being monitored by a UKAS accredited certification body to ensure compliance. These windows and doors will have undergone a large number of tests to ensure that they keep bad weather and burglars out. As with most British Standards, this is a minimum standard. (Previously Security Standard BS7950)
Egress RequirementsAt least one window in each bedroom must be of sufficient size to permit occupants to escape a fire and to allow a fully outfitted firefighter to enter. An egress window must satisfy all four International Residential Code (IRC) criteria. The bottom of the egress window opening can't exceed 44” from the finished floor. The minimum opening area of the egress window is 5.7 square feet. The minimum egress window opening height is 24” high. The minimum egress window opening is 20” wide
BSI KitemarkedThe Kitemark is a UK product and service quality trade mark which is owned and operated by The British Standards Institution (BSI Group). The Kitemark is most frequently used to identify products where safety is paramount
CE Marking"CE" is the abbreviation of French phrase "Conformité Européene" which literally means "European Conformity". Directive 93/68/EEC in 1993
UK to BS EN14351-1:2006Relates to windows and doors, without resistance to fire and/or smoke leakage
BS6375-1:2009Relates to the performance of windows and doors with regard to weather-tightness