Building Control - Replacing windows

Since April 2002, all replacement glazing came within the control of the Building Regulations and anyone who installs replacement window frames or glazed doors must comply with the thermal and safety performance standards as set by the Building Regulations. This is to ensure reduce heat loss in homes and consequently energy and help to meet increasingly stringent national and global energy saving targets.

Building Regulations also prohibits any building work that makes the altered building worse than it already is; therefore existing openable window sizes should not be reduced as this could effect the means of escape in case of fire and the degree of ventilation.

However the replacement of broken glass (or a 'failed' or 'misty' double glazing unit) within an existing window frame or the repair of part of an existing (timber) frame remains uncontrolled "repair work".

The following notes apply to replacement windows of exactly the same dimensions as the existing.

What happens when you come to sell or remortgage your property?

When the time comes to sell or remortgage your property, your purchaser's (mortgage lender) solicitors will ask for evidence that any replacement glazing installed after April 2002 complies with the new Building Regulations.

There are two ways to prove compliance:

  1. Provide a certificate showing that the work has been done by an installer who is registered under the FENSA or CERTASS schemes, or
  2. Provide a Completion Certificate or Regularisation Certificate from the local authority stating that the installation complies with the Building Regulations.

What to do if your replacement window installer is not FENSA or CERTASS registered?

  • If you intend to install replacement windows and your chosen installer is not FENSA or CERTASS registered: You should apply to the local authority to check the installation of the windows. You will need to complete and submit a Building Notice (pdf) at least 48 hours prior to the commencement of the works with the appropriate charge obtained from Table B (under downloads).
  • If you have already installed windows using an installer who is not FENSA or CERTASS registered: You can still make an Application for a Regularisation Certificate (pdf). This will require a Building Control Officer to visit the premises to determine whether or not the window installation is satisfactory. The charge for this can be obtained from Table B (under downloads).

Should you require any further information please contact Building Control Services

Application forms and fee schedules