Two-storey extension plans and drawings in Greater London

Greater London at a glance

Nation: England
Price region: London
Postcode areas: BR, CR, DA, E, EC, EN, HA, IG, KT, N, NW, RM, SE, SM, SW, TN, TW, UB, W, WC
Towns covered: 215 listed below, plus surrounding villages
Site visits: Free, no obligation

What a set of extension plans involves

Two-storey extension plans involve a measured survey of your house, design options, and a set of scaled drawings showing the existing and proposed floor plans, elevations, a site plan and a location plan. These are the drawings needed for a planning application or lawful development certificate. Building regulations drawings with construction details follow as a separate, more technical set.

Greater London towns we list: Brent (HA0), Islington (EC1V), Westminster (SW1), Bexley (DA5), Barking (E6) and Archway (N6). Every other address in Greater London is covered as well.

Fees

Planning drawings (survey and design) are a guide of £2,000–£3,500 and building regulations drawings and specification £1,500–£4,000, with your design stage priced in writing before it starts.

Rules in England

In England, the plans support either a householder application, costing £548 (or £575 for applications made from 8 December 2026), or a lawful development certificate for permitted development, costing £274 (about £288 for applications from 8 December 2026). They must show the extension's relationship to the original house, the boundaries and neighbours, because two-storey rear permitted development depends on the 3 m and 7 m limits.

Approval in England: Householder planning application: £548 (or £575 for applications made from 8 December 2026). Lawful development certificate: £274 (about £288 for applications from 8 December 2026). Councils should decide householder applications within 8 weeks of validation.

Building regulations: Building regulations approval (full plans recommended) from the council or a registered building control approver, with a completion certificate at the end.

The Party Wall etc. Act 1996 applies, so notices may be needed for work on or near a shared wall or boundary.

Getting the design right

Start with a measured survey

Accurate drawings depend on accurate measurements of the house, the boundaries and neighbouring windows. We measure inside and out, note levels, drains and trees, and record the original house so permitted development limits can be checked against the right starting point.

Drawings that can be built

Drawings that ignore steel sizes, floor depths or drain runs often need redesigning once a builder prices them. We coordinate the design with the structural engineer and our build teams, so what is approved is practical to construct.

How we work in Greater London

Visit and first ideas
One of our team visits your house in Greater London, checks the walls, roof and drains, and sketches out options with you.
Plans, then approval
Measured survey, design, then the right approval route for your house. We explain each step before we take it.
Structure and building control
A structural engineer sizes the foundations and steels, and we get building regulations approval before work starts.
Build and sign-off
Vetted teams working under S&K build the extension, and we arrange the building control completion certificate at the end.

Towns we cover in Greater London

Two-storey extension plans and drawings in Greater London: questions

Can I use plans from a previous owner's planning permission?

Sometimes. If the permission is still valid, usually within three years of the decision in England, you can build to it. The drawings may still need updating for building regulations, and the design may not suit your needs. We check old plans and permissions at the free site visit.

How long do extension plans take to prepare?

Survey, design and planning drawings usually take 4 to 8 weeks, depending on how many options you want to explore. Technical design, structural calculations and building control approval take a further 4 to 8 weeks, and this can overlap with the planning decision period.

Do I own the plans once they are drawn?

You receive copies of the drawings to use for your project, including your planning application and building regulations approval. Copyright in drawings normally stays with whoever prepares them unless agreed otherwise. Your written design stage price sets out how the drawings can be used.

Neighbouring areas

All extension services in Greater London · About two-storey extension plans and drawings