Building Regulations apply to building work in England & Wales and set standards for the design and construction of buildings to ensure the health and safety of people in and around those buildings. They also include requirements to ensure that fuel and power are conserved and facilities are provided for people, including those with disabilities, to access and move around inside buildings. Scotland has its own set of Building Regulations.
What is "Building Work"? The following types of project amount to 'Building Work': The erection or extension of a building. An alteration or renovation project involving work which will temporarily or permanently affect the ongoing compliance of the building, service or fitting with the requirements relating to structure, fire, or access to and use of buildings. When installing replacement windows using a Builder or window company not FENSA registered. The installation or extension of a service or fitting which is controlled under the regulations.
The insertion of insulation into a cavity wall.
The underpinning of the foundations of a building.
When you want to change the building's fundamental use.
If your building work consists only of the installation of certain types of services or fittings (e.g. some types of drain, fuel burning appliances, replacement windows, WCs, and showers) and you employ an installer registered with a relevant scheme designated in the Building Regulations (a competent person), that installer may be able to self-certify the work. If the building work to your home, building or property is more substantial then you may need to seek Building Regulations guidance and approval. This is a separate matter from obtaining planning permission for your work. Similarly, receiving any planning permission which your work may require is not the same as taking action to ensure that it complies with the Building Regulations.