Building Regulations For Replacement Windows – Are There Any?

How do you stay within building regulations whilst replacing windows? As specialists in steel window and doors, we will guide you through everything you need to know. Complying to building regulations for replacement windows will not only benefit you in terms of energy performance. Should you ever sell our home, the buyer’s surveyor will require to see evidence of any windows replaced after April 2002. Failure to provide this information will be noted by the purchases solicitor and may lead to further problems finalising the sale. 

Regulations Overview 

Since 2002, it has been a requirement that you must see approval from the Building Control Department of your local council to show that replacements have been made in accordance with building regulations. The regulations apply for both England and Wales. However, there are some differences should you live in Scotland and Northern Ireland. 

New replacement window fittings must comply with regulations. It is important to note that the replacement of glass only is not covered by the regulations.

How To Ensure You Comply With Regulations

There are a couple of ways that ensure that you comply with regulations. For both, you will need to obtain a certificate to prove your compliance. 

Firstly, you can apply to your local council building control officer to get a certificate. This certificate will confirm that installations are completed in accordance with the regulations. 

Alternatively, you can get a competent person who has been registered to self-certify under a competent persons scheme to provide a certificate after installations are complete. 

All windows, including any roof-lights and roof windows, must meet the requirements in the regulations. They must also be fitted to comply with any relevant sections of the building regulations. 

What Regulations Must Be Met

Regulations that you must comply with when replacing windows include, but are not limited to: 

  • L1 Conservation of fuel and power – This means that windows you use must attain the required U value. To achieve this you may be asked to prove that the glass you use is of a recognised quality and make. You may also be required to provide calculations to show how the U value has been attained. 
  • N1 Glazing protection against impact – These rules surround the height of windows as well as the type of glass used for them. 
  • Structural regulations in Approved Document A considers the support above windows and whether they are suitable. 
  • Approved document B considers how occupants may escape in the case of a fire. 

It is of utmost importance if your home is listed on a conservation area that you acquire planning permission. However, there may be exceptions or exemptions with regards to particular aspects of the building regulations to ensure that planning rules can be adhered to. 


It is essential when you replace any windows in your home that you comply with building regulations. Doing so will help you improve the energy performance of your home. It will also help, should you ever wish to sell your home. Some key regulations that must be followed include the L1 conservation of fuel and power which requires your windows to attain the required U value. Additionally, the N1 glazing protection against impact regulations must be adhered to when it comes to the height and type of glass used in your windows. 

Jennyfields – Steel Window And Doors 

Our team of specialists for steel window and doors can confidently provide you the top quality service you need. We are a trusted family-run business operating with domestic and commercial clients throughout the South East of England for 35 years. For any questions or further information about our services, get in touch with us here. Give us a call on 01252 978238 or email us at We’d love to hear from you! Take a look at our steel replacement services and features here.