Most house extensions require Building Regulations approval even where planning permission is not needed. Planning and Building Regulations are separate systems: a project can be permitted development for planning purposes and still require Building Regulations compliance.
Why Building Regulations still apply
Building Regulations set functional requirements for matters including structure, fire safety, ventilation, energy efficiency, drainage, electrical safety and other technical aspects of building work. The approval route and information needed depend on the work and the building-control process used.
Typical extension design issues
Common technical issues include foundations, wall and roof construction, beams over new openings, stability, insulation and thermal bridging, windows and doors, ventilation, drainage, means of escape where relevant, electrical work and the relationship between the extension and the existing house.
Planning approval is not Building Regulations approval
Planning primarily deals with development and land-use considerations. Building Regulations deal with technical standards. Receiving one approval does not automatically satisfy the other regime.
Why coordinated drawings help
A coordinated Building Regulations drawing package can show construction build-ups, dimensions, fire and ventilation notes, insulation standards, drainage principles and interfaces with structural design. Structural calculations may need to be supplied separately where beams, posts, foundations or other structural alterations are involved.
How Archi Project can help
The Planning + Building Regulations package can include technical drawings and specification notes plus agreed Part L, glazing, PV and electrical design calculations. Structural engineering is available separately through Archiproject Structural Engineers where required.
Frequently asked questions
If my extension is permitted development, do I still need Building Regulations?
Usually yes. Planning status and Building Regulations approval are separate questions.
Do all extensions need structural calculations?
Not every extension needs bespoke calculations for every element, but structural calculations are commonly required for beams, large openings, posts, foundations or non-standard structural arrangements.
Is an EPC included?
No. Where an EPC is required it must be commissioned separately from an accredited energy assessor.
Official sources
These are the principal official sources used for this guide.