Two-Storey Extension Plans and Drawings

What you get

This service suits you if you want clear, accurate plans for a two-storey extension, whether to apply for planning, check permitted development or get build prices. You get a measured survey, sketch options with guide costs, a chosen design developed into planning drawings and, if you go ahead, building regulations drawings coordinated with the structural engineer. Because we also build, the drawings are prepared with the build in mind.

It suits you if…

You want to see what your house could take before committing
You need planning drawings or a lawful development certificate application
You want drawings prepared by people who also build extensions
You want design options with guide costs, not just one scheme

Design points that matter

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.

Compare options early

Sketching two or three layouts, such as rear, side or part two-storey, is the cheapest point to make big decisions. Each option comes with a guide cost and a view on the approval route, so you choose with the full picture rather than discovering limits later.

Planning drawings versus building regulations drawings

Planning drawings show what the extension looks like and how it affects neighbours. Building regulations drawings show how it is built: foundations, structure, insulation, fire safety, ventilation and drainage. Most two-storey extensions need both, prepared at different stages.

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.

Planning and approvals by nation

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.

Wales

In Wales, the plans need to show the measurements the Welsh rules depend on: the 4 m and 3 m rear depths, the 10.5 m distances to boundaries and, for side extensions, the 1 m set-back and 50% width test. A householder application costs £585. Building regulations drawings follow the Welsh Approved Documents.

Approval in Wales: Householder planning application: £585. Councils normally decide householder applications within 8 weeks.

Building regulations: Building regulations approval under the Welsh Approved Documents, which differ from England's in places (notably energy efficiency).

Scotland

In Scotland, the plans support a householder application, costing £371, and later a building warrant application with technical drawings to the Scottish Building Standards Technical Handbooks. Because Class 1B needs 10 m to every boundary, the site plan showing boundary distances is often what decides the route.

Approval in Scotland: Householder planning application: £371. Councils have two months to decide a local planning application.

Building standards: A building warrant from the council's building standards service before work starts, and a completion certificate at the end. Scotland uses its own Technical Handbooks.

Northern Ireland

In Northern Ireland, the plans support a planning application to the local council, costing £347 per dwelling, or show that a rear extension meets the 3 m and 7 m permitted development limits. Building control drawings to the Building Regulations (Northern Ireland) and Technical Booklets follow.

Approval in Northern Ireland: Planning application for works to a house: £347. Councils aim to decide local applications within an average of 15 weeks; many take longer.

Building control: Building control approval from the local council under the Building Regulations (Northern Ireland), using the Technical Booklets.

Guide price

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.

Item	Typical cost
Planning drawings (survey and design)	£2,000–£3,500
Building regulations drawings and specification	£1,500–£4,000
Structural engineer (calculations and beam design)	£750–£2,200
Building control or building warrant fee	£800–£1,900
Party wall surveyor, one agreed surveyor (England and Wales only)	£1,300–£1,500 plus VAT

What's included

Measured survey of the house and plot
Two or three sketch options with guide costs
Existing and proposed plans and elevations
Site plan and location plan
Permitted development check
Planning or lawful development certificate drawings
Building regulations drawings coordinated with the engineer

How it works

Free site visit
We look at your house, the boundaries, access and drains, and talk through what you need the new space to do.
Design and approval
Measured survey and drawings, then planning permission or a lawful development certificate, depending on the rules where you live.
Engineering and fixed price
Structural calculations and building regulations approval, then a fixed build price in writing.
Build and sign-off
Vetted teams working under S&K build it, and we arrange the completion certificate.

Questions about two-storey extension plans and drawings

What drawings do I need for a two-storey extension?

Usually two sets. Planning drawings, or drawings for a lawful development certificate, show the existing and proposed plans and elevations, a site plan and a location plan. Building regulations drawings then add construction details, structure, insulation and fire safety. In Scotland the second set supports a building warrant.

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.

Do the plans include structural calculations?

Not at planning stage. Structural calculations and beam design are prepared by a structural engineer once the design is agreed, and they form part of the building regulations package. We coordinate the engineer's work with the drawings so steel sizes and floor depths match.

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.

Related services

Planning permission for two-storey extensions

Getting planning permission for a two-storey extension involves checking whether permitted development applies, preparing drawings and supporting information, submitting a householder application to the council and dealing with questions until a decision is made.

Learn more

Building regulations for two-storey extensions

Building regulations approval for a two-storey extension involves preparing technical drawings and a specification that show how the extension meets the rules on structure, fire safety, insulation, ventilation, electrics and drainage, getting them approved and having the work inspected.

Learn more

Design and build two-storey extensions

A design and build project for a two-storey extension involves one team taking responsibility for the whole job: the survey, design, planning or permitted development, structural engineering, building regulations, party wall matters where they apply and the construction itself.