Building Control guidance - replacement windows

With effect from 1st April 2002 replacement windows and doors in all buildings must comply with the Building Regulations. The requirement applies where complete frames are to be replaced but not to the replacement of individual panes within a frame. The new units must meet the specification referred to in Approved Document Part L1 for thermal insulation standards and also in terms of safety, as covered by Part N. Also, the openings areas providing ventilation and means of escape from fire should not be worse than with the existing installation.

Since 1st October 2010 replacement windows are required to meet the same insulation standards as newly installed windows.

Energy conservation

One of the main reasons for the change is the need to reduce energy loss. The Building Regulations have controlled glazing in new buildings for many years but they represent only a very small percentage of our total building stock. It is also essential to improve the performance of the much larger numbers of existing buildings if we are to meet increasingly stringent national and global energy saving targets.

When the time comes to sell your property, your purchaser's surveyors will ask for evidence that any replacement glazing installed after April 2002 complies with the relevant Building Regulations. There are two ways to prove compliance:

  • A certificate showing that the work has been done by an installer who is registered under a recognised Competent Persons Scheme; or
  • A certificate from the local authority saying that the installation has approval under the Building Regulations
  • Find out more about the Competent Persons Scheme.

It is estimated that around 2 million installations of replacement glazing happen every year. That makes it essential to have a way to ensure that the work is done properly without unreasonable increase in the administrative and financial burden on installers and property owners.

The answer is the Competent Persons Scheme, which allows installation companies that meet certain criteria to self- certify that their work complies with the Building Regulations.

The scheme requires all completed installations to be registered with the Competent Persons Scheme Governing Body (such as FENSA, BM TRADA, BSI). Completed installations are also registered with the relevant Local Authority.

A final certificate should also be issued to the householder confirming compliance.

Any installation carried out by a firm which is not registered to self-certify, including work done as a DIY project by a householder, needs approval under the Building Regulations. You, as the house owner, are ultimately responsible for ensuring the work complies with the Building Regulations.

There have been several reports of installers who are neither members of a Competent Persons scheme, nor bothering to make applications to the council. Remember, it may delay or even stop the sale of your home if you cannot prove the replacement glazing was done legally. Before you sign a contract to buy replacement glazing, be sure to ask whether the installer is able to self-certify. If not, an application will have to be made to your local authority for approval under the Building Regulations.