Replacement Window Notice application guidance notes

Guidance notes for a Replacement Windows / Doors application

From 1 April 2002, Building Regulations requires that building owners installing replacement windows or doors (being a door which together with its frame has more than 50% of its internal face area glazed) 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
  • K4: Protection against impact with glazing.

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 units or repair of rotten or damaged frame members is not subject to Building Regulation approval.

There are two ways that you can ensure compliance with relevant regulations, firstly you may employ a contractor or installer who is registered under the FENSA self-certification scheme (or other relevant competent persons scheme). This contractor will be approved to carry out the work in accordance with relevant regulations without inspection by the council and will inform FENSA (or other relevant competent persons scheme) when the installation has been completed. So an application to the Local Authority is not required.

Alternatively, if your contractor is not registered with FENSA (or other relevant competent persons scheme), you must submit an application to the council.

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 or lintel above the replacement window or door.

Requirement B1 - Means of escape in fire

All windows to habitable rooms (but not kitchen, utility rooms, dressing rooms, bathrooms, wc's or shower rooms) at floors above ground level are required to be suitable for escape in fires. 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 at least 0.33sqm and at least 450mm high and 450mm width (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

See the table below for current requirements. If your original windows have trickle ventilation 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 an alternative approach to the ventilation provisions listed in the table below, the overall provisions for background ventilation for the dwelling should be equivalent to an average of 6000mm² per room for the rooms listed, with a minimum of 4000mm² in each room.

Ventilation: current requirements for various room
RoomRapid ventilation
(e.g. Opening window area)
Background ventilation
(i.e. trickle vents)
Habitable room1/20th of the floor area of the room served8000mm²
Kitchen and utilityOpening window (no minimum size)4000mm²
Bathroom or shower roomsOpening window (no minimum size)4000mm²
Sanitary accomodation1/20th of the floor area of the room served4000mm²

J2 - Combustion appliances and fuel storage systems

Certain fires and heating appliances rely on air filtration for them to function correctly. They may require purpose made ventilators, or, may have relied on air filtration through existing ill-fitting windows and doors. If you have an open flued appliance in the house that does not have separate provision of combustion air, a check should be made by a suitable qualified person (Gas Safe, HETAS, etc) to ensure that adequate permanent combustion ventilation is provided. The boiler or fire manufacturer's advice should be followed with regard to proximity of opening windows and doors.

K2 - Protection from falling

Where a first floor window cill height is less than 800mm above the floor level suitable guarding should be provided to prevent a person falling through an open window.

The requirement may conflict with Regulation B1 and provision of escape windows. One way of achieving the requirement may be to provide a restricted opening device that can be easily overridden in the event of an emergency.

K4 - Protection against impact with glazing

Glazing in the shaded area indicated in diagram below should either:

  • Break safely as defined in BS6206:1981 Specification for impact performance requirements for flat safety glass and safety plastics for use in building, clause 5.3.
  • Be inherently robust, i.e. annealed glass, glass blocks, polycarbonates or glass that gains strength through thickness.
  • Be in small panes (a maximum area of 0.5m2 with a maximum width of 250mm is acceptable). Annealed glass should be not less that 6mm thick, except where it is in traditional leaded or copper lights in which 4mm glass is considered acceptable when fire resistance is not a factor.
  • Be permanently protected by a suitable screen which has a minimum height of 800mm and which incorporates a gap no greater than 75mm.

Critical locations in internal and external walls

Shaded areas show critical locations to which safety glazing should be fitted (i.e. glazing in areas numbered 2,4,5,6,7 and 8).

L1 - Conservation of fuel and power

All UPVC and wood replacement windows should attain a U value of 1.6 w/m2K. One way of achieving this requirement is to install frames having a Window Energy Rating of Band C or better.

This is not the only option, but if another system is used, certification may be required to prove that a U value of 1.6 w/m2K is attained.

M2 - Access and facilities for disabled people

Where the property was subject to the Disabled Regulations, any new principal entrance door should have a minimum 775mm clear opening with a low threshold. The new arrangement should be no less compliant than the existing.

Application notes

A building notice is valid for three years but work can begin as soon as 2 days after you have submitted your application. You must let us know when work starts and it is completed.

Charges - Once the application has been received electronically we will reply back to inform you of the correct fee and how to pay it. To help improve or service to you and minimise costs please accurately write any e-mail addresses and daytime contact numbers. It is not possible to withdraw your application once it is has been registered. A decision will be issued as soon as possible after that time.

In addition to Building Regulation consent you may require Planning Permission, Listed Building Consent or Conservation Area Consent. Please check using the Planning Portal or ring the planning help line on 0161 253 5432.

The information given by you on this form is held and controlled by Bury Council. The information is held for the purpose of the council's functions under the Building Act 1984. The information provided may be disclosed to third parties who make legitimate enquires regarding the application of the Building Act 1984 to the building(s) concerned.

Further information or help concerning the submission of Building Control Applications may be obtained from Building Control Help Line: 0161-253-5313 or by e-mail to