Window Handles for Double Glazing
Double glazing is a term used for a more modern day window where two panes of glass are combined into one unit for the purpose of heat insulation. These types of windows came into fashion during the 1970's when windows were generally a single pane of glass and found mostly on wooden or steel framed windows.
Handles for Aluminium Double Glazed Windows
These were the first modern day double glazed windows and were combined with a hardwood outer-frame liner. The initial designs were an improvement on the older single glazed timber window but still suffered from heat loss. These types of windows relied heavily on the use of cockspur window handles as the means for opening and closing the window. Cockspur handles were generally quite standard utilising a 9mm step size and a 5mm wedge. You would most likely attribute the handle to its predecessor on a timber window although the mounting of the catch is slightly different. Older design aluminium double glazing casement windows will therefore use a cockspur window handle with a 9mm step size and a 5mm wedge block.
Aside from the casement window there is another type of window that became popular with the advent of double glazing and one we inherited from our friends in Germany. The tilt and turn window is still seen today here in the UK but has diminished in popularity mostly because these are heavy mechanical inward opening windows and interfere with sill boards, net curtains etc. When it came to the design of this window the window handle was a major challenge and you will find all sorts of different designs of handles where a fork or blade attachment would drive the movement of the locking points around the window. If you are trying to replace a window handle on these type of windows you are in for a major challenge yourself.
Aluminium windows are still made for the double glazing market although most tend to be for commercial applications like shopfronts or stores. Today's domesticated aluminium window will most likely use espag handles to work the multi-point locks and these tend to be with a 9mm long spindle (10mm) as the frames are not very deep.
Summary: Old double glazed aluminium windows will use cockspur handles with a 9mm step size. Larger non casement windows like tilt and turn will incorporate bladed type handles and locks and may not be found any more for replacement. Modern day windows will use espag handles with a short spindle.
Handles for UPVC Double Glazed Windows (or PVC-U for its correct term)
The need for thermal insulation of an aluminium window drove the development of the upvc double glazed window and many of the German extrusion companies then started to develop the casement window profiles for the UK market in the early 80's. Mass production of upvc windows was established in the UK with some of the giant names like C R Smith, St Helens Glass, Everest, Anglian and Thermastor.
The development of the window hardware is still somewhat of an opportunity for many manufacturers as weather performance, security and safety are all driven by the components of hardware like handles, hinges, locks etc. Needless to say the early day upvc windows were very basic when it came to window handles both in terms of options as well as the basic ability for key locking which we all now take for granted. Like its predecessor the aluminum double glazed window, the upvc window took off with the use of the cockspur window handle. These are still found today on many older upvc windows but very rarely on new modern day windows. These handles differed from the aluminium double glazed window cockspur handle only by the step size as the upvc window has bulkier frames requiring a wider backset. Aluminium windows are typically quite slim by virtue of their inherent metal strength so only requiring the smallest step size of 9mm.
As the need for more security was becoming a necessity the development of window hardware moved on at a pace to incorporate what we now know as multi-point locks. These are fitted around the opening window to give a stronger brace to the opener and to pull the sash into the frame for better weather performance (the cockspur handle window would use two handles on each opener in many cases to overcome this). The initial multi-point lock handles were fitted with a blade to engage into the lock itself and these were typically found on Everest windows and similar. These are very difficult handles to replace as they are no longer made. Similarly the use of a rounded cranked spindle became popular with window manufacturers like St Helens Glass and again these are no longer found in production.
Thankfully some form of standardisation took place during the 90's when the espag window handle came to the fore and has remained ever since. This is just a handle with a 7mm spindle and fixes into the gearbox of the upvc window. The fixing tends to be standard at 43mm centres via two M5 countersunk machine screws.
Summary: Old upvc windows used cockspur handles in varying step sizes. Between the cockspur and the espag lock came the bladed multi-point locks like the Cadenza handles which can still be replaced. New upvc windows use espag handles in varying lengths from 9mm upto 55m long spindles - the spindle is always 7mm square.
Handles for Timber Double Glazed Windows
Wooden windows are now part of the modern double glazed window scene and are making a comeback to compete with the PVCu domestic window. Various wood treatments and wood types from sustainable sources are being used to provide long lasting weather sealed and secure windows just like the upvc and aluminium types. The character of a true wooden window is hard to beat and you will find that much of the development of the pvcu window came from the features and aesthetics associated with wooden window frames over the years.
It's no surprise then the comeback of the timber window means that all of the hardware development over the years, particularly by the upvc industry, has been incorporated into the timber double glazed window. From its introduction the use of espag handles has been typical, and you'll find that most timber windows are 7mm squared spindles (made in the UK) and 8mm spindles from places like Scandanavia. Scandanavia export a lot of timber into the UK from sustainable sources and the quality of their windows is well received, although their hardware provides some replacement challenges along the way.
All timber window espag handles have spindles and a lot of them have 30mm long spindles as standard in the UK, like those made by popular manufacturers John Carr (Jeld Wen) and Boulton and Paul over the years. Of course these windows should not be confused with the more traditional wooden windows which are latch and catch based handles.
One of the time-served methods of anchoring an open window is to use a window stay or peg stay as found on the older designs of timber windows. The new double glazed versions can also use them it seems so the benefits of both the espag handles and the window stays combined make a powerful force, as some upvc window manufacturers are replicating by using dummy stays on upvc cottage type windows.
Summary: Double glazed timber windows are likely to have espag handles with a 30mm long spindle. The UK version is a 7mm square metal spindle and the Scandanavian is 8mm. Some wooden frame double glazing combine peg stays with espag handles.