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Part L Building Regulations

Replacement Windows and Doors

As from 1 April 2002, Building Regulations request that building owners installing replacement windows or doors must obtain Building Regulations consent and have the installation inspected to ensure compliance with relevant regulations.

The relevant regulations are:

  • L1 Conservation of fuel and power
  • N1 Glazing protection against impact

In addition, you must also ensure that replacement windows and doors are no less suitable than the existing windows and doors in relation to the following regulations:

  • A1 Structure
  • B1 Means of escape in fire
  • F1 Means of ventilation
  • J2 Combustion appliances and fuel storage systems
  • K2 Protection from falling
  • M2 Access and facilities for disabled people

Repair work, such as replacement glazing or repair of rotten or damaged frame members is not subject to Building Regulation approval.

Guidance on how to satisfy the requirements

Requirement A1-structure.

When installing new windows or doors an assessment should be undertaken by the contractor as to the suitability of the support of lintel above the replacement window or door.

Requirement B1- means of escape in fire

All windows to habitable rooms (but not kitchens, utility rooms, dressing rooms, bathrooms, wc's or shower rooms) at floors above ground level are required to be3 suitable for escape in fire. In addition, rooms at ground floor level whose only escape route is via another room must be provided with suitable escape windows.

A suitable escape window is defined as 'a window whose unobstructed openable area is alt least 0.33m2 and at least 450mm high and 450mm wide (a 450mm wide opening will need to be 735mm high).

The bottom of the openable area should be no more than 1100mm above the floor. Any key required to open the window should be readily available.

F1-means of ventilation

For current requirements. If your original windows have trickle ventilators any replacement frames should also be provided with such. The area of opening windows should not be less than that which was originally provided.

As and alternative approach to the ventilation provisions listed in table 1 below, the overall provisions for background ventilations for the dwelling should be equivalent to an average of 6000mm2 per room for the rooms listed, with a minimum provision of 4000mm2 in each room.