Planning permission and building regulations are separate controls. A home extension in England can fall within permitted development for planning purposes and still require building regulations approval. Treating the two as the same process is one of the easiest ways to create delays later.
What building regulations cover
Building regulations deal with technical standards such as structure, fire safety, ventilation, thermal performance, drainage, electrical safety and access. The exact requirements depend on the work.
For an extension, issues can include foundations, walls, roof structure, insulation, glazing, drainage connections, electrical work and how the new space connects to the existing house.
Planning permission is a different question
Some extensions in England can be built under permitted development rights if they meet the relevant limits and conditions. Others need a planning application. That decision does not remove the separate need to comply with building regulations.
Check planning status and building-control requirements as two separate items before work starts.
Choose the building-control route before construction
Depending on the work and project route, approval may be handled through a local authority building control body or another authorised building-control route. Some individual trades can self-certify eligible work through authorised competent-person schemes.
Do not leave this until the end. Building control may need to inspect work while important elements are still visible.
Expect inspections during the work
Building-control inspections can cover stages such as foundations, drainage, structural work, insulation or completion, depending on the project. The exact inspection plan is determined by the building-control body and the work being undertaken.
If work is covered before a required inspection, proving compliance later can become more difficult.
Keep certificates from specialist installers
Where registered competent-person installers self-certify eligible work, keep the certificates they provide. GOV.UK says registered installers can notify the local authority and provide a compliance certificate after completion.
Electrical, heating, window or other specialist work may generate separate documentation that forms part of the property's compliance record.
Do not rely on the builder alone for the paperwork
A builder may coordinate building control, but the homeowner should still understand who is responsible for applications, notifications, inspections and certificates. Put that responsibility in writing before work starts.
Typical extension checks
- planning permission or permitted-development position;
- building-regulations approval route;
- structural design where required;
- drainage and foundations;
- thermal and fire-safety requirements;
- electrical and heating compliance;
- inspection stages;
- completion and self-certification documents.
Sources and verification
- GOV.UK — Building regulations approval: when approval is required and routes to compliance.
- GOV.UK — Use a competent person scheme: self-certification, notification and compliance certificates.
- GOV.UK — Building work, replacements and repairs to your home: homeowner compliance routes and checking registered installers.
- Planning Portal — Extensions: planning and building-regulations guidance for domestic extensions in England.
Jurisdiction note: this article describes the system in England. Building-control and planning arrangements differ elsewhere in the UK.