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Types of Window Frame

Windows are not simply a hole in the wall; they are made to provide an aesthetic finish to the home and blend in with the overall architectural design. They must also function well as a means of letting fresh air in and keeping cold air and bad weather outside. If your windows are getting draughty or look out of place compared with your home's modern additions, perhaps it is time to look for new window frames.

Modern window replacements can be purchased in UPVC, hardwood or aluminium designs. Whilst UPVC is the most popular material used in modern windows it is still worth investigating the other options before making your choice. All makes of window frame are now designed to try to fit modern demands, so you may find a wood or aluminium frame to suit your usage as well as your home's appearance.



UPVC windows are made from Unplasticised Polyvinyl Chloride, which are now the most widely used replacement window frames in the UK. Their popularity is largely due to their relative cheapness when compared with hardwood and aluminium frames, but it is also due to their long-term cost effectiveness.

The installation of UPVC windows often takes place because the original timber frames have become rotten. Unlike wood frames, UPVC is a hardy material that needs little maintenance over the years. It will not need any protective coating or re-painting as time passes, saving you money better spent elsewhere. Money will also be saved on your heating bill as UPVC is designed to highly insulating and resistant to bad weather. Reducing the drafts that were previously let in by your old wood frames will consequently decrease your heating costs and save energy. As well as insulating against the elements, UPVC windows are better at noise reduction.

Many people rely on UPVC as the most secure of window materials. It is a strong and solid structure in its frame, and comes with a range of security locks. However, the PVC itself is not very firm, and often relies on internal support which can lower the U rating.

One of the criticisms levelled at UPVC frames are the lack of colour choice. The standard colour is white, but if you feel that would not suit your home there is usually also a choice of mahogany or oak effects. With the increasing popularity of UPVC it is even possible to get it specially made in almost any colour you like, including black, red, orange and green. Discolouration in UPVC is rare and is usually warranted against, but if you are looking a special colour it is worth discussing it with your supplier.

The designs of the frames will vary between companies, so there are a couple of issues you should investigate:

1. UPVC systems are often multi walled and contain inner reinforcement involving either aluminium or a galvanised steel box. This walling will vary, although most are based around 3 - 3.5mm in thickness. The thicker the walling, the stronger the reinforcement will be.

2. The frame extrusion can range between 50mm to about 70mm, and will evidently also affect the structural strength of the frame. Be aware of this when looking at prices.

UPVC is not applicable to all properties as it is not a traditional style. It cannot be used on listed buildings and may be objected to in conservation areas or areas that aim to portray a traditional image.

Environmental concerns - As PVC in general increases in popularity, so do the voices of concern. Part of the process in making PVC derives from oil which is a non-renewable source. Moreover, the actual manufacturing process in UPVC window frames creates more waste and uses up to eight times more energy than the manufacture of timber windows. The production industry surrounding PVC products presents a toxic threat at all stages, and some PVC products have been known to present a health threat in releasing harmful chemicals.

A major selling point for UPVC windows is their long life. PVC is non-biodegradable and whilst this is great for our home maintenance it is not good for the environment. Landfills are seeing more PVC goods that may cause long term environmental issues. It cannot be burned because it will release toxic gas, and recycling is difficult due to the various chemicals used in each PVC product.

Hardwood/Timber Frames

hardwood/timber frames

Hardwood styles suit traditional and natural looking building designs. Wood window frames can be more aesthetically appealing, even when getting a little rough round the edges. Wood frames including hardwood, pine and cedar are nowadays mostly installed on listed properties or on those in conservation areas.

As it is associated with old, traditional properties, wood as a window frame material is often regarded as inferior under all criteria except its appearance. However, many timber frames now incorporate double glazing in keeping with modern demands. The wooden frame itself is applied with weather stripping and other weather proof or insulating developments that are a big improvement on traditional draughty, flimsy frames. However the better the wood insulation: the higher the price. Buying new brush seal insulation or weather stripping for your hardwood windows will still be cheaper than buying new UPVC, and properly maintained they can last just as long. Cheaply made timber frames can be prone to cracking or warping in harsh weathers.

Timber will always require some occasional maintenance, but there is no reason why with modern paints, stains, and wood treatments that your windows will not last. The wood stains and paints available also give you more variety in colour for a cheaper price than UPVC, so you can update your home's appearance as often as you like without having to change the frames.

As with UPVC windows, the thickness of the frame will affect its strength so compare this against the price. Most timber frames are made using mortise and tenon joints, but you can talk to your supplier about other methods available. The beauty of timber frame installations is that you can have them designed bespoke by a joiner to replicate any style you wish; you do not have to buy 'off the shelf' designs. This will cost a great deal more than standard UPVC frames but it can add value, style and authenticity to your property.

Environmental concerns - Of the three main window frame materials, wood is arguably the most environmentally friendly to us as it is biodegradable and a renewable resource. However, if you are particularly sensitive to environmental issues you may wish to seek a locally-sourced supplier of wood so it will that it not need transporting as far, and ensure that all trees cut down for these purposes have a good replanting system. FSC (Forest Stewardship Council) sourced timber is the best for environmental compliance.

Aluminium Windows

During the 1960s when double glazing began to grow in popularity, aluminium was the window frame material of choice. It combines strength and lightness, making it a good product for the homeowner and for the installer. Aluminium resists warping, rotting or twisting and like UPVC is a low maintenance material. The frames are light and slim, and so allow for a more unobstructed view and daylight source.

So why is aluminium no longer a popular choice for window frames? UPVC was produced as a cheaper alternative. However due to their strength, aluminium windows are still are fairly common addition to commercial buildings or other places where security and rigidity are an issue. Compared with UPVC, aluminium also offers quite low insulation and was prone to condensation. It is recommended nowadays that you buy aluminium frames that contain a "thermal break" which split the frame components into interior and exterior pieces with a less conductive element placed in between.

Like timber frames, aluminium can come in a range of colours to suit your home. Powder coating is often the method used for colouration though, and once the frame has been powder coated it cannot be repainted.

As aluminium has declined in usage it is harder to find a supplier. This makes it more expensive still as there is little competition to create lower prices. As with UPVC, aluminium windows are usually prohibited from being installed on listed buildings and frowned upon in other living areas.

Environmental concerns - Aluminium is a highly recyclable material, and generally products can be remade like for like; so that old aluminium window your parents replaced could be remade into a new aluminium window for you. However, some coatings applied to aluminium make this difficult this, so anodizing is the preferred technique for the environmentalist. Aluminium is not a renewable resource in itself. Those with environmental concerns should also be aware that the manufacturing of aluminium uses quite a lot of energy.