Thinking of replacing your windows? Since April 2002, all replacement glazing has come within the scope of the Building Regulations. Any replacement windows or doors have to comply with strict thermal performance standards.

One of the main reasons for this change in 2002 was the need to reduce energy loss. The Building Regulations have controlled glazing in new buildings for many years but this represents only a very small percentage of total building stock. It is also essential to improve the performance of the much larger number of existing buildings if increasingly stringent national and global energy saving targets are to be met.

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

1. A certificate showing that the work has been done by an installer who is registered under FENSA Scheme
2. A certificate from the Local Authority saying that the installation has approval under the Building Regulations.

It is estimated that around 1-1.2 million installations of replacement glazing happen every year. If all of them went through the normal Building Regulations application process it would place an enormous burden on local authorities. It is essential to have a way to ensure that the work is done properly without an unreasonable increase in the administrative and financial burden on installers and property owners. The answer is a scheme which allows installation companies that meet certain criteria to self-certify that their work complies with the Building Regulations. The scheme is known as FENSA, which stands for The Fenestration Self-Assessment Scheme, it operates in England and Wales and meets with central Government approval.

A sample of the work of every installer will be inspected by FENSA appointed inspectors to ensure standards are maintained. FENSA will also inform local authorities of all completed FENSA installations and issue certificates to householders confirming compliance. FENSA members are also obliged to offer consumers an insurance-backed guarantee.

Any installation done by a firm which is not registered to self-certify, or done as a DIY project by a householder, will need full local authority approval under the Building Regulations. Local authorities will know of all the approved installers in their areas and will be able to identify unauthorised work very easily. You should note that, as the house owner, you are ultimately responsible for ensuring that any work complies with the Building Regulations.

Before you sign a contract to buy replacement glazing, be sure to ask whether the installer is able to self-certify. If not, either they, or you, will need to make an application to your local authority for approval under the Building Regulations and pay the relevant charges.