Building Regulations

Part M "Access and Facilities For Disabled Use"

The approved document is intended to make access for disabled visitors. A number of different provisions are covered, including the need to provide accessible thresholds and minimum opening widths to the principle entrance of the dwelling.

This entrance is usually considered to be the "front door" but it is possible that the siting or design of the dwelling may, for practical reasons, prevent the front door being the entrance for the wheelchair bound.

Door Size:

The clear opening width of the door must be at least 775mm. This is measured between the door stile and the face of the door when it is opened to a 90 degree angle. Any door fittings or weatherboard projections are ignored.

Timber Thresholds:

The use of the current cill is acceptable providing:

  • It is fitted with a waterbar not exceeding a vertical rise of 15mm
  • The top of the timber cill is set level with FFT.

Part B "Fire Safety"

In July 2000, this approved document introduced a new concept of emergency egress windows to dwellings with an upper floor level not exceeding 4.5m. Provision is to be made for emergency egress windows to habitable rooms to the first floor of two storey dwellings, unless a fire protected route is provided from those rooms to the final exit.

Emergency egress windows are not required to ground floor habitable rooms unless they are inner rooms (i.e. rooms not leading directly into a hallway).

Three storey properties do not require emergency egress windows to ground or first floor habitable rooms, as they have to be protected with a fire protected route in any case.

The window must provide:

  • An unobstructed opening of at least 0.33m2
  • A minimum dimension in height or width of 450mm


  • The escape route must not exceed 1100mm from FFL


  • An escape route of 450mm x 740mm will satisfy
  • The unobstructed opening may be angled

Timber Windows

The rules permit the opening to be of any shape provided the minimum dimensions are met.

If the windows are subject to Secured by Design requirements, the window will need to be fitted with laminated glass.

Part L "Conservation Of Fuel And Power"

What is document L?

Document L is the part of the Building Regulations that sets the standards of energy efficiency in buildings.

Why Is it continually being amended?

As part of the Kyoto agreement, the UK Government has made commitments to reduce emissions of greenhouse gasses, such as Carbon Dioxide, which are harmful to the environment. Generation of the energy we use to heat, light and cool our buildings accounts for almost half of the Carbon Dioxide emissions in the UK. Therefore the Government is endeavouring to reduce energy consumption by making properties more thermally efficient.

What are the changes?

The changes require the use of more energy efficient building materials (for example those used in walls, roofs, windows and floors). All building products will have to meet a certain thermal performance, measured as a U-value.

What is a U-value?

The U-value measures the rate at which heat is lost through a material. The lower the U-value, the lower the amount of heat lost and the lower the amount of energy wasted.

What is low-E glass?

It is a glass which has a thermally enhanced coating designed to absorb shortwave radiation (e.g. heat from the sun) and reflect longwave radiation (e.g. heat from radiators) back into the room.