Building Regulations for Windows and Doors

The building regulations that apply to windows and doors are numerous but many of them can be adhered to simply by buying what you need from a mainstream supplier. Look for companies that can prove compliance and registration with a recognised scheme such as BSI, CERTAS or FENSA as they can deal with the certification and the Local Authority approval on your behalf.

The areas covered by the regulations are:

• Thermal performance
• Safety
• Means of escape
• Air supply and ventilation

Some of the regulations, such as ventilation, thermal efficiency apply to how the windows and doors are constructed, while means of escape and fire safety are more about how and where the windows and doors are fitted. General safety can fit in either category.

Thermal Efficiency

Energy efficiency is a hot potato at the moment and the government has tightened up many regulations in this area in recent years. The regulations regarding the U-Value, the amount of heat allowed to pass through the glass and framework of a window or door, are complex. There are also different ratings depending on whether the windows and doors are to be used in an extension or as replacements in an existing dwelling.

Most manufacturers will be aware of these ratings and their use, and will be able to sell you compliant units. If they don't seem to understand the question or gloss over it then it's safer to walk away.

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Air Supply and Ventilation

It's the existence of air supply and ventilation regulations that account for the little vents with closable covers that began to appear on double glazing units a decade or so back. It was discovered that having completely airtight rooms, something that was quite possible with modern double-glazing and the focus on draught-proofing that we have today, brought its own hazards.

The amount of ventilation required will differ depending on the way a room is being used, with bathrooms and utility rooms, for example, requiring more ventilation capability than bedrooms or lounges.

Your situation may be slightly different. ask a question below ↓ and our editorial team will reply with our advice.

Safety Issues

Safety is a widespread issue too. Firstly there is the use of safety glazing, which must be used when the glass is installed in what the regulations refer to as a 'critical area'. This is defined in the regulations as:

• Any glazed area within a window below 800mm from floor level
• Any glazed area within a window that is 300mm or less from a door and up to 1500mm from floor level
• Within any glazed door up to 1500mm from floor level

Again the manufacturer should be able to comply with this without any problem.

Other safety issues regard the placement of the doors and windows within the extension, usually with regard to escape from fire. It is regarded as good practice to install escape windows, i.e. those that can open wide enough for people to easily pass through, on the first floor and any higher than that. Fire regulations also govern the thickness and fire resistant nature of internal doors.

Bay Windows

Finally one tricky one to note is that adding a bay window to an existing home will be treated in planning and building regulation terms, as an extension. So if your extension has bay windows and you want to convert some in the current house to balance the overall design, you will have to get building regulation approval for that as well as the main extension.

The Next Step

Now that you have read through the advice above, you might want to put it into practice. Our Planning Permission Checker lets you tell us about your planned extension and find out whether you need planning permission or can build under permitted development. Try it now →