Buying Windows

If you are simply buying a designed package, you may remain blissfully unaware of the thinking behind the window choice presented to you. There are certain things, however, you should be well aware of:

• For a whole house, you can spend as little as £3,000 or as much as £50,000 on windows and joinery 

• There is a wide range of styles from every period and movement of architecture

• Windows open and close using a variety of methods 

• There is a huge range of materials 

• You need to decide just how energy efficient you want your windows to be

Where to Buy

If you want something mainstream – plastic or timber in regulation dimensions – then you will find that your local builders’ merchant will provide very competitive quotes. The joinery merchants tend to publish price lists and then offer discounts off these lists to entice a sale: depending on the state of the market and the size of your order, the discounts can vary from 30% to 50%. They will also offer cavity closing systems which make fitting in blockwork walls a much simpler option.

If you require something more specialised, you will have to negotiate directly with suppliers or importers. Local joinery shops are often good places to do business, though they can be slow and expensive. Imported windows tend to be at the top end of the price spectrum and can often involve large cash deposits and/or upfront payments: check the terms closely.

There are also numerous specialist manufacturers in the UK producing unusual windows, such as steel or laminated oak. The more active ones are likely to be encountered exhibiting at Homebuilding & Renovating Shows, where you can make direct contact with them. Take note of lead times — occasionally these can be many weeks, which can cause stresses on the build programme if not planned well in advance.

Size

In order to keep costs down, British housebuilders and joinery manufacturers use a modular approach to window openings. If you open a joinery catalogue from the likes of Magnet, Speedframe or JELD-WEN, this will become immediately apparent. The window heights step up in 150mm intervals (two brick courses) whilst the standard widths for casement windows are set at 630mm, 1,200mm and 1,770mm, though there are often some intermediary widths available.Most conventional designs stick to these opening sizes; if you vary from them, you immediately add a 20% to 40% premium for making up a special.

Imported windows are either all made to measure or follow some other standard size convention, so this invariably makes them an expensive option relative to home-produced standard windows.

Fitting

It’s important to discuss who will fit the windows and if there are any routines needed to fit them. The industry trend is moving away from site-fixed frames towards factory-finished windows which tend to be fitted much later in the build programme. Factory-fitted windows are also very heavy and sometimes require specialist equipment for fitting, so it’s a good idea to discuss fitting options with your chosen window supplier.

Whilst some window systems are awkward to fit, others are dead simple. There is an increasing use of cavity closers which also act as sub-frames for both plastic and timber windows; one of the great advantages of using such systems is that the windows are designed to clip into place, fairly late in the build programme. If you are working in timber frame, the windows may well be offered as a pre-fitted option, although you can also elect for a late fit, should you wish. You need to work out who will fit the windows and at what stage of the build, and if there will be any charge for this service. Traditionally, bricklayers built the joinery into the walls as they went about their work at no extra charge, but the growth in factory-glazed windows is causing old practices to die away.

Another issue to think about is where exactly within the wall structure the windows should be situated. Setting them back from the outside is good practice from a weathering point of view but usually involves external cills and window surrounds, which can cost as much as the windows themselves. If you are replacing windows in an existing house, the work is now covered by the Building Regulations. If you want to avoid the hassle of having to apply for these, you can elect to use a FENSA contractor who can sign off the work (England and Wales only).

Look

There are a number of window styles that have evolved over the years and they tend to be closely linked with particular periods of architecture. If you are restoring or extending a period property, you will want to use windows which complement the styles used elsewhere. The major British joinery manufacturers all produce ranges of windows to suit the main periods – i.e. Georgian, Victorian, Edwardian – in both casement and sliding sash styles. And there are still numerous specialists, such as Crittall, producing steel window frames for 1930s-style houses.

If you are working with contemporary stylings, then there is a much wider choice as you can also consider windows and styles originating in other countries. Bear in mind that the trend towards thicker glazing units makes it harder and more expensive to produce authentic-looking period windows, which tend to have small glass panes, and this in itself has become a factor in the move away from period stylings in new houses.

Cost

It’s a complex picture and the accompanying chart (below), which shows the ranges in cost for the different window materials and styles, attempts to summarise it.

It’s useful to rank window costs on a square metre basis. Suppliers tend to hate this because you don’t buy windows by the square metre: they are priced individually and generally the larger the actual window, the less it costs per square metre, so reducing a window range down to a square metre price is never going to produce an accurate pricing method. But from a comparison point of view, it’s a very useful tool. The square metre rates are derived from taking the total amount quoted to supply windows and dividing this by the area of the window openings.

The cheapest way of supplying and fitting windows to a new house is to use white PVCu windows, designed to slip into industry-standard window openings. Although you can buy softwood frames for less, by the time you have glazed and painted or stained them, they end up being considerably more than the cheapest PVCu options. However, note that PVCu windows themselves can vary enormously in price, depending on quality, style and colour — the wood grain effects are around 50% more expensive than white. Though they can look very good in the right setting, a lot of people really dislike the idea of plastic windows and insist on timber; in fact, sales of timber windows have recently begun to rise again after many years of losing out to plastic.What often turns people off timber is the requirement for regular maintenance: most timber requires repainting or staining every five years. If you want maintenancefree timber windows, you have to switch to one of the composite systems, which tend to be timber based but have aluminium external claddings.

Energy Efficiency

There have been enormous improvements in the energy performance of windows over the years. The move from single to double glazing was largely a result of us demanding better energy performance from windows and the past 20 years has seen several other improvements, notably the introduction of low-E glass, gas filling of the cavities, warm edge spacers and the adoption of wider cavities. The Building Regulations have slowly tightened the demands made of our glazing systems and currently they demand a U-value of 1.8 or less, which requires most of the above features. But the very best windows available on the market achieve U-values of less than half this amount; these are invariably triple glazed and tend to be imported from countries such as Sweden and Germany. There is little demand for triple glazing in the UK as yet and very few manufacturers are prepared to tool up to produce triple glazed units until there is proven to be a consistent demand. If you want to go for a really lowenergy window (look for a U-value of around 0.8 or less), you’ll almost certainly have to import it and your style options will be limited — it will look modern.

It is worth noting that the U-value method of measuring energy efficiency, whilst fine for walls, roofs and floors, is rather clumsy for windows because they are also capable of taking heat in. The British Fenestration Rating Council (BFRC) has developed an alternative method of ranking windows and we are seeing an increasing use of its energy rating symbols, from A down to G. As well as assessing the U-value of the whole frame assembly, this rating also looks at how good the windows are at absorbing heat during the daytime, and assesses the overall frames for airtightness as well.

Opening Mechanisms

If you stick with a traditional British window, it will either tend to open outwards on a side-hung hinge (known as a casement window) or slide up and down (known as a sliding sash, as used by the Georgians and the Victorians) However, other countries tend to use different mechanisms. The North Americans use a lot of screw thread openers, whilst the Europeans, who have always preferred windows that open inwards, tend to like various swivelled opening mechanisms and, in particular, the tilt-and-turn window which has been a standard in Germany for 50 years. Tilt-and-turn windows can open along the side hinges or the bottom hinges, depending on how you operate the handle. In comparison, British windows are crude and simple, but they do open outwards which suits our love of curtains. In contrast, the continental systems are designed with external shutters in mind.

Sound Proofing

If you live next to a main road, a railway or under a flight path, you will want your windows to keep the noise out. There are a couple of things to be aware of. Firstly, look to avoid windows that have ventilation or trickle vents built into them (which British-made off-the-shelf ones tend to). These are placed in many windows as standard as a method of introducing fresh air into a house, but they are also a pathway for noise. If you do away with trickle vents, you will need to provide an alternative method of ventilation.

Secondly, the best air gap between panes of glass for sound proofing is around 30mm, but this is too much for double glazing (ideally 16mm). Consequently, if sound proofing is a major issue, people sometimes prefer a secondary glazing system fitted internally. Several Swedish joinery manufacturers sell a product called a ‘2 + 1’, a low-noise window which consists of a double glazed window plus an extra single glazed leaf.

Security

Our fire regulations require that bedrooms in new houses must have an egress window, i.e. one from which you can readily escape. These must have a clear opening of at least 0.33m² and the opening must be less than 1,100mm from the floor. Most large windows easily comply with this requirement and British joinery manufacturers have engineered their existing ranges so that even small windows can still qualify as egress windows. But do check that your choice of window will satisfy the building inspector. There is also a requirement for low windows (below 800mm above floor level) to have toughened glass.

The other aspect of security concerns break-ins and how to avoid them. The simplest upgrade you can undertake is to specify toughened glass, but there is a more demanding standard, known as BS 7950, which is sometimes used on ‘Secured by Design’ schemes. This usually involves fitting shoot-bolts on the opening windows and fitting laminated glass externally. Sometimes double glazing is specified using laminated glass externally and toughened glass internally. In addition, it’s important to consider upgrading the standard supplied locking mechanisms to a more sturdy alternative.

Further reading:

• Positioning windows
• PVCu windows: A green option?
• A Guide to Windows & Doors