Replacement Windows and Doors

Building Control Technical Guidance Leaflet No. 14

Replacement Windows & Doors

This leaflet is one of a series produced by the Hertfordshire Building Control Technical Forum


After April 2002, all replacement glazing came within the scope of the Building Regulations. Anyone installing replacement windows or doors has to comply with strict thermal performance standards. 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 these represent a very small proportion of our housing stock. We now seek to improve the performance of the much larger numbers of existing buildings if we are to meet the stringent but essential new national and global energy saving targets.

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

1 – Provide a certificate showing that the work was carried out by an installer registered under one of the following schemes:

  • Fenestration Self Assessment (FENSA) scheme;
  • Certification And Self Assessment (Certass) scheme;
  • BM Trada (BM TRADA);
  • British Standards Institute (BSI) or

2 – Provide a certificate from the Local Authority confirming that the installation was approved under the Building Regulations.

The Self-Assessment Schemes

It is estimated that around 2 million replacement glazing installations are completed each year. Local Authorities would be placed under immense pressure if all these were to be assessed under the normal application process. It is however essential to find a way to ensure that work is done properly without imposing an excessive financial and administrative burden on householders and installers. The schemes highlighted above all meet Central Government requirements. A sample of the work of each installer will be assessed by appointed inspectors to ensure standards are maintained. These bodies will also notify Local Authorities of all completed CPS installations, and issue their own certificates to householders confirming compliance.

To see more read the full PDF here