Generally speaking windows in any building are required to perform the task of letting in light and provide adequate ventilation but there is so much more than that to consider when specifying new windows.

If you are replacing existing windows you’ll generally be allowed to replace the windows on a like for like basis without having to seek Building Regulations or Planning Permission. Today though we are often looking to update the appearance of the property and there are so many style and colour options available for windows allowing you the opportunity to be creative with your design and maximise your property’s full potential to be the home of your dreams. You may have to obtain permission if the changes you intend to make are considerably different to the existing windows.

New windows are key to saving energy and the thermal performance is addressed in Document L of Building Regulations and the Window Energy Rating scale is used on all new windows to indicate the U-value of a window (in much the same format as is used for electrical appliances). The lower the U-value of the overall window frame and glass combined then the more energy saving it will be.

Security should also be a crucial part of your specification for windows as they are the weakest point of entry for burglaries and again the Building Regulations set out minimum security standards for new windows. We supply and install windows that meet the British Standard criteria for security and have Secure by Design status.

Low maintenance is a standard requirement these days, UPVC and Aluminium are almost maintenance free. Painted Timber will require some attention but modern factory- applied finishes will continue to look good for up to 10 years before you will need to reapply any paint or stain coatings. Of course, regular cleaning and maintenance of moving parts is essential for the longevity of serviceable life for all window materials.

Window Styles

Casement windows glazed with CN Heritage slim double glazing

Casement windows glazed with CN Heritage slim double glazing


Casement windows are a style of window that open and close inward or outward and are permanently attached in the window frame. The casement sash is the moveable part of the window that holds glass panes. The casement sash is connected to the frame and opens with hinges on one side. A popular combination for casement windows is an opening fan light window hinged at the top above a side hung or fixed pane.

Retaining the original windows


A sash window is a window feature composed of two frames or sashes which slide to open. Most sliding sash windows are double-hung, allowing both sashes to open, and set on a vertical track with one sliding in front of the other, often called a Box Sash Window.  Sash windows are often used in traditional style properties and now they can also be replicated to resemble a sliding sash but actually open as a tilt inward from the bottom of each sash.


A Bay window is formed from several casement windows projecting from an outside wall forming a square or rectangular alcove in a room, normally having its own foundations.

CN Glass bow and bay windows


A Bow window is a curved window comprising of several casement windows projecting from an outside wall forming an alcove in a room. A Bow window sticks out from the wall of a house and is usually supported underneath in some way or it could have its own foundations.

CN Glass tilt and turn windows


Top swing windows are most commonly used in multi-storey structures where cleaning from the inside is necessary. By reversing the sash it makes this the safest and most useful type of window for cleaning from inside a building. Top swing windows are constructed with a top reversible hinge. The window is equipped with a safety catch that restricts opening.


A tilt and turn window fundamentally opens on two axis: tilting when ventilation is needed and turning inwards to open up the whole frame, mainly to provide a means of escape from a room in case of fire. In the tilt position, the window tilts inwards into the room – remaining fixed at the base.


UPVC windows are the most affordable frames and the woodgrain coloured foils really do look lovely making it difficult to identify them as plastic. UPVC windows come in all styles of window, casement, tilt and turn and also a traditional sliding sash. They are 100% recyclable too.

Aluminium windows are right on trend for designer homes and often specified by Architects. Colours are powder coated onto the Aluminium and the frame thickness is usually slimmer than UPVC. Modern home styles of a cream colour flat rendering look particularly good with dark coloured Aluminium frames or they make an excellent replacement for the traditional, sometimes industrial metal Crittall style windows.

Timber windows are the most expensive and they will either be softwood or hardwood, there is no longer much difference in cost and the timber is responsibly sourced and traceable. The coatings come with long guarantees and will retain their beautiful appearance for many years. Timber has qualities of warmth and tradition and somehow they just always look particularly beautiful installed into any style of building.


CN Glass have always strived to be competitively priced and also provide the best products available. As a rule of thumb we advise that it is worth selecting a first-class product, whatever material you choose. and this is exactly what we aim to supply to our customers.

We install windows to the exacting methods set out by The Glass and Glazing Federation. We have been members of the GGF since 2000 and we are a founder member of FENSA.

Being the industry authority the GGF promotes best practice and sets the highest technical and health and safety standards. By using a Glass and Glazing Federation (GGF) Member company, you are dealing with the elite companies in the industry – established, trusted companies, working to the highest professional standards and installing high quality products as well as guaranteeing you the unrivalled GGF consumer protection.

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