Door glass & glazed panels
For a long time, glazing was just for windows. Door designs began to use glass as a decorative feature, starting with fanlights and top lights. The glass areas were kept to a minimum due to draughts, but as glazing technology improved, glass could be used more freely.
Nowadays, doors are double glazed as standard and, like windows, can be upgraded to triple glazing. Large glass panels are used in patio doors, whereas entrance doors tend to feature smaller glazed 'cassettes'.
Sidelights and other shaped top lights are a popular feature of entranceways nowadays. Matched with decorative glass in the door leaf, they can add a touch of class to the front of your property.
Glass in doors
Door glazing works in exactly the same way as window glazing. Glass panes are sealed together by a 'spacer bar' around the outside, with a cavity or space between the panes. This gap is often filled with an inert gas to slow down heat loss.
The overall glass panel is called a 'sealed unit', and units with two and three panes of glass are available – typically referred to as double and triple glazing. The extra pane of glass and gas cavity slow down the escape of heat, leading to a much more energy efficient door.
Double vs. triple glazed doors
Double glazing in doors is now the norm – in fact it's specified in the Building Regulations. But both entrance and patio doors are now available with triple glazed units. With improvements in seals and frame technology, it's a shame for the glazing to let down the overall energy rating of the door!
Triple glazed doors provide next-level insulation - they're up to 35% more effective than double glazing for energy efficiency. Triple glazing helps to retain heat generated within the home, whilst reducing overheating in summer. Recognising the benefits of triple glazing, some door companies now offer triple glazed entrance doors as standard.
Decorative or stained glass panes can be incorporated into your new entrance door and side windows, resulting in a totally unique design. Glass panels in doors are available in variety of shapes, sizes and patterns.
Coloured and bevelled glass pieces are joined together by metal 'cames' – the leading or metal bar you traditionally see in stained glass windows. To match your colour scheme, you can choose from a range of finishes, such as brass, zinc or black leading. Stained glass designs can be incorporated into double glazed doors, but to protect the glass design it's better to contain within a triple glazed unit.
Other decorative glass options include etched designs, where patterns are cut into the glass by using a stencil and sandblasting. This creates a white, shade-like effect. In this way, you can personalise your property with house numbers and names in the glass.
Leaded glass is typically a 'criss cross' design, either with square or diamond patterns. Leading can be applied to the outside of the glass, or inside for ease of cleaning. Alternatively, you could choose Georgian bars to divide the glass into squares, giving your doors a traditional 'cottage' look.
Typical of Georgian and other period windows, leaded glass designs are ideal for top lights and sidelights – the glazing surrounding an entrance door. You should be able to incorporate leading into any type of glazed product, such as patio doors and even conservatories.
Obscure, or privacy, glass distorts the view through the glass, hiding the inside of your home from prying eyes. You'll commonly see privacy glass used in back doors and bathroom windows, as they let in the same amount of light, without displaying the contents of your home to outsiders. That's why obscure glass is ideal for entrance doors and even front porches.
You can choose from a range of obscure glass, such as floral, geometric and cloudy designs.
There are two ways that glass can be secured for use in residential doors. Toughened glass is heat-treated to be stronger, whilst laminated glass is coated with an invisibly thin layer of plastic that stops a cracked pane from breaking into pieces.
Safety glass must be used in doors up to a height of 1500mm, in accordance with the building regulations. That means fully glazed doors must use thermally toughened glass, and even entrance doors with glass units below 1.5 metres must comply.
Glass doors are now designed to reduce heat loss and gain natural heat from the sun. This is because they feature 'low E' or low emissivity glass, which has an invisible, thin coating applied to the inner pane of glass to retain heat. This helps to maintain a comfortable temperature indoors. Solar glass is especially useful for patio doors, bi-folding doors and conservatories, where large glass areas would previously lose heat quickly.
One of the problems associated with solar glass is that it can lead to overheating on very hot days. There are ways of combatting this – a good glazing company will be able to help you position windows and doors to avoid this problem. Triple glazing is also useful – research also shows that contrary to popular opinion, it can actually protect against excessive heat gain, rather than contributing to the problem.