Building Regulation Drawings for Extensions

Yes. In almost all cases, a home extension requires Building Regulations approval, and building regulation drawings form part of that approval process.

You will normally need Building Regulations if the extension involves new foundations, new external walls or roofs, structural openings or steel beams, changes to insulation or energy performance, drainage alterations, or kitchens and bathrooms that require ventilation.

If the work affects structure, fire safety, insulation, drainage or ventilation, it is classed as work that requires building regulations. Drawings will be needed so Building Control can assess compliance before construction progresses.

When do I need Building Regulations drawings?

Building regulation drawings are usually required before building work starts, particularly where a Full Plans building control application is being made.

In practice, drawings are needed before submitting a building control submission, before inspections begin on site, and before foundations and structural work are carried out.

Starting work without drawings often leads to inspection failures, delays or requests to open up completed work so compliance can be checked properly.

A typical drawings package for an extension includes existing and proposed building plans, sections through the extension and existing house, detailed technical plans at key junctions, insulation build-ups for walls, floors and roofs, drainage and ventilation layouts, and details and building regulations notes.

For more complex projects, the drawings package may also include structural calculations prepared by a structural engineer.

Yes. In almost all cases, a home extension requires Building Regulations approval, and building regulation drawings form part of that approval process.

You will normally need Building Regulations if the extension involves new foundations, new external walls or roofs, structural openings or steel beams, changes to insulation or energy performance, drainage alterations, or kitchens and bathrooms that require ventilation.

If the work affects structure, fire safety, insulation, drainage or ventilation, it is classed as work that requires building regulations. Drawings will be needed so Building Control can assess compliance before construction progresses.

Detailed building regulations plans are prepared to show exactly how building an extension will comply with current Building Regulations.

These plans are technical documents used by Building Control to assess compliance before work starts and to inspect the building work as it progresses on site.

For most projects, the extension will need a clear set of application drawings that demonstrate how the proposed construction will meet building regulations. This applies whether the work is a rear extension, side extension or part of a larger building project.

Drawings cost varies depending on the complexity of the project.

Factors that affect cost include the size and layout of the extension, foundation design, drainage alterations, and whether conversion or loft work is included.

For a detailed breakdown, see building regulation drawings cost.

What happens if building work is carried out without approval?

If building work is carried out without Building Regulations approval, Building Control may require a regularisation application.

This often involves opening up parts of the work so inspections can take place. Additional drawings and construction details may also be requested, which can delay completion and increase costs.