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Glossary of terms
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Ensure you know exactly what’s on your new "Classic" or "Authentic" windows.....
.............a glossary of terms to help you decide.
Over the years we have seen so many homes disfigured and properties devalued, either because the homeowner choose the cheapest option, (not understanding how their windows would affect the appearance of their home), or the window company failed to design a sympathetic solution to suit the property.
The objective of this booklet is to provide details of the components that can be included on your windows, to enable you to make an informed decision.
We have no desire to overcharge you, we would much prefer you to purchase a basic product and be happy with your choice, than purchase windows with lots of costly extras that you may not require, and are unnecessary.
Every window we manufacture is bespoke, its tailored to meet your requirements exactly, so it is vital that we explain the choices available to you.
In this way, you can decide in your own time, those important items that will benefit you, and remove those unnecessary items so that costs are kept to a minimum.
Above all you understand that you do have choices, and therefore be confident that your choices are right for your budget and will suit your home.
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Traditionally, double-glazing companies have found the cheapest and easiest way to put Georgian bars on to windows. This is evident with most companies putting Georgian "canes" inside the two sheets of glass. They rarely look real and act as an immediate give away.
Cheap to produce, but extremely dull and a very poor imitation of the real thing.
The brilliant white bars never get rained on so at first they "may" look similar to the rest of your new windows, but in time they will shout out "DOUBLE GLAZING" as they stay brilliant white against the weathered feel of the rest of the window.
That’s one way that cheap double-glazing can devalue your property! With our windows you have a choice.
Internal bars, if cost is the only factor, however these do not look realistic.
Or surface mounted, "real-feel", bonded astragal bars which add a third dimension to your windows, protruding from the surface of the glass the way the muntin bars did on the originals... creating depth, character and shadow lines.
Remember the equalisation of layout as mentioned in the "sash" description earlier.
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Goods in transit are liable to move about. It’s natural and impossible to prevent, be it movement in the factory, delivery vehicle or just the fitters installing the window.
Not surprisingly then, sometimes the balance springs would slip off the "shoe" slide designed to connect the balance and sash together. When the balance slips off, it means a service call and the window being inoperable because only one side is being lifted.
With every window of ours, the balances are held firmly in place with a retaining clip that once snapped into position locks the balance in place for life.
You will never need a service engineer to make any adjustments because the balances have become detached.
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These are what make your sash windows work... just as the weights did in the original windows.
Originally, on timber windows, the weight of the glass and sash was counterbalanced by a lead weight on the end of the cord. This meant that wooden windows would be easy to open (when not painted shut) and remain in the position required because the sash was the equal to the lead weights and so counter balanced.
Little or no effort was necessary to move the sash because there is no friction between the sash and the frame, that’s why they were often drafty and rattled.
Today, manufacturers have 5 basic types of balances to open the windows. Each is designed for a purpose and requires differing amounts of effort to raise or lower the sash...
- Clock springs or constant force balances
- Block and tackle or cord and pulley
- Wind up (Alumatilt)
- Pretensioned Spirals (Ultralift)
- Double springs and spirals (TORSO)
Whilst some manufacturers import goods from the USA direct, we source all our balances from a company that specialises in making balances, indeed they make each of the 5 types of balance listed and this is a summary of their experiences...
Should you need detailed information, check them out at www.caldwell.co.uk
Clock springs are exactly that. A little like a metal tape measure on its side, which unfolds when the windows are operated. Coupled with larger weights when required, they are used extensively in America for secondary or ultra lightweight windows. Tested to AMA (American Manufactures Association) they are not expected to exceed more than 3,000 opening cycles. Very competitive, but Caldwell refuse to import them into the UK as they are simply not sturdy enough for the UK market.
Block and Tackle. Again, extensively used in the USA on small lightweight windows. A nylon cord approx 2mm in diameter, wrapped around a pulley system and encased in a three sided channel, these balances are not expected to exceed 3,000 cycles and, again, not imported to the UK by Caldwell.
Wind-ups or Alumatilt. This is a lightweight continuous tube, encasing a twisted metal rod. These balances are sturdy, and competitive. However, because they need to be "wound up" they retain a twisted force throughout their, 5,000 cycles. This can lead to frequent adjustments normally demonstrated when a sash is opened and it drops a couple of inches by itself! A 2 year warranty is average for a product that is highly likely to require some adjustment through its life.
Pre-tensioned Spirals or Ultralift. A smooth operating balance with the tension "factory set" or pre-tensioned. These sturdy balances, are designed for weights up to 28kgs. We have had these independently tested at the BBA to exceed 20,000 cycles (that’s over 25 years if opened twice a day). A 5 year warranty for this reliable, factory set balance is entirely justified.
Double springs and spirals or TORSO. The Rolls Royce of balances!
Designed by a Dutchman in 1946, they epitomise great engineering. Individually manufactured in 0.5kg increments (1lb), and tailored for perfect lengths, these balances have two springs; one wound clockwise, the other anti clockwise. So as a sash is opened, one spring is getting longer and the other compressing, getting shorter... counterbalancing each other for their entire life.
This means they are immensely reliable.
When being tested for a Post Office Counters project they exceeded 50,000 cycles or simulated 68 years life expectancy if opened twice a day (actually they switched off the machine after 180,000 cycles!). The Torso balance is the premier of all balances, perfect for any size of window, and as such is covered by a 10 year warranty.
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Brush Pile with Central Fin
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Again, nothing standard about the brush piles being used.
Our windows even has a brush pile with a special central plastic strip designed to retain its shape far longer than less costly piles, and increase the resistance to draughts by 30% extra.
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This was perhaps the weakest part on old sash windows, as burglars would flick the latch with a butter knife!
With a choice of colours, the key locking cam provides all the strength required to deter unwanted visitors.
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 Well firstly, both are multi-chambered. This means there are three individual pockets inside the sections.
This enables the galvanised steel reinforcement to be sealed in its own department, well away from the separate drainage channel which allows water to clear away easily.
Secondly, three chambers are better at insulation than two.
That’s how our company was the first to achieve an eco friendly, energy efficiency "green" rating. 4.16.4 units generally provide U values better than 1.8 however our classic windows achieved the new D energy rating using low Iron glass. Please ask for further details.
Most importantly however, when extruding companies compete for market position, introducing new products (to tempt manufacturers and homeowners alike), they often do so at the cost of authenticity... that’s why the we have our own sash profiles designed to recreate the "putty line" that virtually all sash windows had originally.
However, if an Ovolo detail is required externally on the sash, that’s also available. Internally most beading and bars were Ovolo in shape... that’s exactly what you get with our windows.
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 To prevent moisture ingress, every window of ours has foam pads especially designed to the shape of your frame sections. These pads will compress when the frame and cill sections are screwed together, which means a compact and effective barrier to moisture ingress.
This costs more, but since inventing the pads in 1994 our box sash windows have never failed our customers.
In addition, the brush piles are cut back to prevent them acting as wicks and drawing water into your home... and then, as a final preventative measure for your complete peace of mind, we add a short silicone seal as well.
We don’t take any chances with your home. By spending extra on the manufacturing process, we are protecting you from the inconvenience and disappointment you would feel if your walls became damp after installation of your windows.
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 With most companies supplying sash windows, little attention is given to sightlines... how a window is framed in an opening.
Traditionally, the lower sash rail was often made from 4" or 5" timbers, planed to about 100mm, as this rail had to carry the most weight.
Obviously it would be far easier to weld four profiles of equal size, but this would not simulate the detail of the existing windows.
By combining three different profile sizes you can be certain that the proportions are as close to the original timber window as is possible. |
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Old sash windows do not have any seals, they relied on the wood being manufactured to a snug fit.
Unfortunately over the years they warp or swell, or get painted shut or have bits planed off so they end up rattling and draughty.
Modern materials are expected to retain their shape forever, not needing to be planed or painted and the window sections are extruded with small retaining channels for brush piles to be inserted around the edges of the sashes.
Wind however finds any weak spots!
That’s why when we test our windows in extreme conditions (our windows are installed in the Lands End Hotel and Outer Hebrides) and we find a soft spot, we go on to invent a solution... in this case foam baffles.
Every window of ours is then fitted with these as standard, irrespective of where in the country it’s being installed.
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A 3 sided construction that is welded at the top corners. Where the two frame jambs join the cill, most window manufacturers will apply a wet silicone seal to help prevent leaks or moisture ingress through your frames.
This can be risky as sometimes the windows are moved before the silicone sets... or even worse; it is forgotten to be applied.
You won’t know this has happened until you see damp patches on the internal walls around your window frames! This cannot happen with our windows.
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 The cam catch, limit stops, tilt knobs, pole eye and scroll handles are available in gold/brass, chrome and white. |
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Whilst astragal bars recreate the original feel of bars, of the companies that fit them, most rely on adhesive tapes to keep them in place, but consider this...
- How do you open your existing sash windows?
- Do you use the handles?
Probably not, because most people push, pull, or even lift their sash windows using the Georgian bars... that causes a big problem, the bars come off in your hand! This happens because most companies that copy the concept will cut the bars into small pieces, a typical 6 over 6 design would have 20 separate bars on the window.
Our window is again unique.
The clever, patented design of interlocking the bars where they meet, together with unique Georgi-clips (again patented to our company), mean that each bar is continuous and cut the full size of the sash.
The bars then interlock with each other and are securely attached to the glass at each end. In other words, they are taped, interlocked and clamped onto the glass surface, belt bracers and a piece of string…so confident are we with this technology that we’re happy for you to open and close the largest of our sashes using the bars... they wont come off.
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These are moulded decorative extras below the top sash.
Originally their purpose was to prevent the sash being pulled down too far and loosening the lead weights inside the box.
Today they are purely decorative, recreating the traditional appearance of box sash windows. Using the highest grade ASA compound you can be certain these will not fade or discolour, and unlike other companies these are firmly secured to the sash, not relying upon springs that often pop out!
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To make the job of installation easier (and handy if you need to move furniture through a window), are the two part pivot bars. These metal brackets are designed to facilitate sashes to be quickly, safely removed and easily reinstalled.
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 These are spring-loaded devices that prevent a window from opening beyond 100mm … particularly useful for children’s bedrooms.
It is possible to use nylon versions, as other manufacturers do, but these cannot be locked, which is far from ideal and it is much safer to have a key or other method to ensure your limit stops stay locked.
Just in case you’re wondering why there are two limit stops on your windows, this is because experience has shown that fitting just one will, over time, cause the lower sash to twist.
Constant banging of the lower sash against the limit stop forces the lower sash into a trapezoidal shape, loosening the glass setting blocks, which leads to the glass becoming loose in the sash.
By fitting a pair of limit stops, any force from banging the sashes is equalised, actually keeping the sashes square for the life of the window and aesthetically balancing the appearance of the window.
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Pole Eye and Scroll Handles
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The pole eye is fitted to the centre of the top sash (hook and pole can be supplied if required).
Alternatively a D-Handle can be fitted to the outside of the underside of the top sash.
Scroll handles are fitted to the bottom of the bottom sash (please check with the installation team they are positioned as you require them, both for operational use and to suit the Georgian Bar pattern).
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Most extrusion companies who design and profiles will recommend that your sashes be fully reinforced.
This is to prevent deflection in windy weather and to strengthen the sashes so they are capable of carrying the weight of the glass, and providing a strong secure fixing for the handles, latches, and other components.
Sadly, not everyone complies with these rules, and some companies will reduce costs by removing this unseen reinforcement, or only using it very sparingly, which could leave you with a bill for repair... worse still cause an injury.
EVERY piece of sash on our windows has a length of reinforcement that is a full 1.5mm thick... not the 1-1.2mm that is sometimes offered by by others. This gives you much improved strength, greater safety and is the reason why our windows are substantially heavier than most others... they are simply built to last.
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Particularly large sashes cannot be allowed to tilt for cleaning, as the sash is simply too heavy, exceeding the maximum permissible weight to be tilted safely.
Unbelievably, in these circumstances, many companies fit nothing at all!
If lighter sashes can be dangerous, then those which exceed the limits could cause very serious problems. That’s why uniquely, on every Bygone window that exceeds the safe size for the standard easy clean, tilt restrictors, a short pair of safety stays are fitted. So if large windows are accidentally opened they remain vertical, unable to damage anyone or anything.
You’ll find we are the only manufacturer to fit safety stays, which are a shorter version of the tilt restrictor and although they do not allow for cleaning, they WILL prevent accidents.
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 The Sashes usually comprise two sliding squares, each retaining a double-glazed, sealed unit.
In most cases, the "split" in the height will give you equal sashes. Aesthetically however, it’s important to have a clean vertical line through the upper and lower sashes.
You see, most PVC frames incorporate a recess, which means the lower sashes are in fact 20mm wider than the top ones. If the same profile is used top and bottom, it creates a step, which unbalances the window, especially if Georgian or Victorian patterns are being used.
It’s really important to ensure the actual Georgian "squares" are of equal dimension.
Whilst some can be screwed into place as fixed or dummy sashes, they are in essence the same as sliding panes, they simply have the balances, tilt restrictors and other fittings removed.
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 All modern sash windows are designed to tilt inwards to ease cleaning. Short spring loaded "bolts" engage the sash behind the frame section.
Most are just plastic, not very strong and sometimes half moon shaped, a bit difficult sometimes fiddly or cumbersome to operate.
Not with our windows.
Again these latches were specially designed for us, being steel reinforced! The rounded shape of the knob matches that of the cam catches to enhance the beauty of the finished window.
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 Tilt restrictors are metal side arms, made from stainless steel, that allow sliding sashes to be tilted for cleaning safely. With sashes often weighing over 40lbs in weight, it’s vital that a pair of stays are fitted to each sash, both top and bottom.
Some companies will save costs by fitting tilt restrictors to the lower sash only... or by fitting just a single tilt restrictor to each sash.
This is a false economy, as a pair of tilt restrictors on each sash provides double the safety for you, as without them there is a risk that sashes could crash into the room.
Some tilt restrictors are extremely sharp, acting as scissors on the brush pile and therefore reducing the effectiveness of the pile and allowing air to create drafts.
On our windows, the edges have been especially rounded to ensure the tilt restrictor will roll past the brush pile, leaving the pile to do its job... preventing drafts.
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 In today’s homes, it is vital to get good ventilation.
We live in sealed boxes. This can lead to breathing difficulties, stuffy poor air quality and above all a lack of oxygen. Original box sashes provided "natural background ventilation", these were known as draughts!
Architects and Local Authorities suggest that vents should be added to ensure the air is freshened regularly, however they recognise and approve two stage keeps in lieu of trickle vents.
This is great news, as these keeps are far less unsightly than vents and don’t detract from the authentic appearance we stride to achieve.
Remember sash windows are the most efficient at changing air than ANY other style of window.
Why? - because of convection.
As warm air rises, it draws cooled (heavier) air into the room from outside which pushes the warmer, lighter air higher. This circulation is very efficient and is only provided by sash windows.
By fully opening top and bottom sashes, this style of window will replace the average room of air every 20 minutes... keeping the room fresher, cooler and improving breathing whilst you’re asleep!
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We want you to be safe, that’s why we add a warning label to every window.
Windows have tilt restrictors or safety stays, but a newcomer may be surprised to find they tilt inwards, its far better to be safe than sorry!
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