Extension drawings

House extension drawings — planning & building regulations.

Extending your home can be a transformative way to add space, functionality and value — without the upheaval of moving. Whether it's a growing family, a need for a home office or more open-plan living, a home extension offers a tailored solution.

Increased living space
Enhanced property value
More functional layout
Avoids the cost of moving
Customised design

Types of home extension

Common layouts we draw

Rear extension

Best for: Open-plan living · properties with large gardens · semi-detached or detached homes

Up to 3–6 m under permitted development, depending on property type and location.

Side return extension

Best for: Enlarging a kitchen · creating a more spacious, light-filled rear layout

May be allowed under PD if within certain size and height limits.

Wraparound extension

Best for: Large open-plan living, kitchen and dining · homes needing a layout transformation

Usually requires full planning permission due to increased size and impact on neighbours.

Double-storey extension

Best for: Adding bedrooms and bathrooms · larger families or home-based businesses

Not permitted under PD if it extends more than 3 m from the rear wall.

Loft conversion

Best for: Adding a bedroom, office or bathroom in the existing attic

Many loft conversions are permitted development, but mansards usually require full planning.

Garage conversion

Best for: Spare bedroom, office or playroom — minimal disruption to the main structure

Often allowed under permitted development — but check if original garage needed planning.

Basement or cellar conversion

Best for: Urban properties with limited external space · high-value areas like London

Almost always requires planning permission and Building Regulations approval.

Cost guide (2025 estimates)

What does it cost?

Rear extension (single)	£1,800 – £2,500 per sqm
Side return extension	£2,000 – £2,700 per sqm
Wraparound extension	£2,200 – £3,200 per sqm
Double-storey extension	£2,200 – £2,800 per sqm
Loft conversion (dormer)	£40,000 – £60,000+
Garage conversion	£10,000 – £25,000
Basement conversion	£3,000 – £4,500 per sqm

Costs vary by location (London premium), site conditions, finish level and professional fees. Use this as a starting point — get in touch for a per-project quote.

Professional services you may need

The team around your project

Architectural Designer — design and planning drawings
Structural Engineer — load-bearing assessments and calculations
Planning Consultant — help with complex or contentious applications
Quantity Surveyor — cost planning and budget control
Builder / Main Contractor — construction and site management
Party Wall Surveyor — if works impact shared walls

Ready to add space to your home?

From £950 + VAT for Building Regs drawings. Full package from £1,650 + VAT.

Get a quote