Replacing windows or doors

Since April 2002, all replacement glazing has come within the scope of the Building Regulations. That means anyone who installs replacement windows or doors has to comply with strict new thermal performance standards. (Just replacing glass is exempt)

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 this deals only with a very small percentage of our total building stock. In order to improve the performance of the much larger numbers of existing buildings to meet increasingly stringent national and global energy saving targets it was necessary to introduce new regulations.

When the time comes to sell a property, purchasers’ surveyors will ask for evidence to show that any replacement glazing installed after April 2002 complies with the new building regulations. To prove compliance a certificate must be produced to show:

  1. that the work has been done by an installer who is registered to do that sort of work under a Competent Persons Scheme or 
  2. that the local authority has approved the installation under the Building Regulations.

The Competent Persons Schemes

These schemes allow installation companies that meet certain criteria to self-certify that their work complies with the Building Regulations. They were set up by industry bodies, in association with all key stakeholders, and meet with central government approval. A sample of the work of every installer is inspected by FENSA appointed inspectors to ensure standards are maintained and installers who fail to perform can be suspended or even excluded from the scheme. The Competent Persons schemes also inform local authorities of all completed installations and issue certificates to householders confirming compliance.

Any installation done by a firm which is not registered to self-certify, including work done as a DIY project by a householder, needs full local authority approval under the Building Regulations. House owners are ultimately responsible for ensuring that work complies with the Building Regulations.


If you cannot prove that replacement doors and windows have been installed legally it could delay or even stop the sale of your home. Before signing 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 Building Control for approval under the Building Regulations.

For further information, please contact us.