House extension drawings, Durham & the North East
Single or double storey, rear, side or wrap-around. As your extension architect, we design the extension and prepare the planning drawings, building regulations pack and structural calculations to build it, from our Durham office for homeowners across the North East and remotely nationwide.
Designed and engineered to build
An extension is one of the biggest ways to change how your home works, and one of the most common places the paperwork goes wrong. Depending on size, height and position it may be permitted development or need full planning permission, and almost every extension needs building regulations approval and structural calculations. We check the route on day one and, because our architects and structural engineers work under one roof, the steel over a new opening, the foundations and the roof are designed while the layout is still being drawn. As a rough 2026 guide, a single-storey extension costs around £2,000 to £3,000 per square metre to build across most of the UK, so fixing the design and specification before anyone is on site is the best way to control that figure.
- Existing plans, roof plan and elevations from our measured survey
- Proposed plans and elevations showing materials and finishes, refined with you over a reasonable number of revisions
- Planning drawings with a licensed OS location plan, submitted as your agent, or a Certificate of Lawful Development for permitted development
- Building regulations drawings: sections, construction details and a full written specification
- Structural design: foundation plan, steel and timber layouts and calculations lodged with building control
- Single-storey rear, side, front, infill and wrap-around
- First-floor extensions over a garage or existing extension
- Two-storey rear, side, infill and wrap-around
- Kitchen-diners with bi-fold doors and rooflights
- Extensions that open up the wall into the existing house
From first visit to a builder-ready pack
- Site visit and measured survey. We measure the house, levels, openings and drainage, and photograph the areas affected.
- Existing and proposed drawings. Scaled drawings of the house as it stands, then the extension design, refined with you in person or by video call. Survey to agreed design typically takes one to three weeks.
- Planning application, if required. We confirm whether you need full permission or a Certificate of Lawful Development, prepare the drawings in two to three weeks and manage the application as your agent. Councils typically take around eight weeks to decide.
- Building regulations drawings and specification. The technical pack your builder prices and builds from, typically prepared within two to three weeks.
- Structural design. Foundations, beams, lintels and padstones calculated by our in-house engineers, in parallel with the building regulations pack.
- Optional stages. Building control application, tendering to a shortlist of five contractors, and professional eyes on site through the build.
Every stage is fixed in writing before it starts and paid at the start of that stage. See the full nine-stage process.
How our fees work
Every stage is a fixed fee, agreed in writing before it starts, and you only pay for the stages you use. The figure depends on the type of project, the size and type of your property and where it is: site visits outside our local postcode areas (NE, DH, DL, TS and SR) carry a travel charge, projects inside the M25 are priced higher, and listed buildings and conservation areas involve extra work. Council and building control fees are separate and paid directly to them.
- Site visit and measured survey
- Existing and proposed drawings
- Planning application, submitted as your agent, where required
- Building regulations drawings and specification
- Structural design and calculations
- Optional extras such as 3D visuals, party wall notices and site support
The instant quote tool prices every stage separately for your property in about two minutes, with no obligation. If you already have planning drawings, upload them and we send a fixed written proposal.
Planning permission and building regulations for extensions
- Single-storey rear extensions up to 4m deep on a detached house or 3m on any other, or up to 8m and 6m under the Larger Home Extension prior-approval process
- Maximum 4m high, with eaves no higher than 3m within 2m of a boundary
- No more than half the land around the original house covered by extensions and outbuildings
- Materials similar to the existing house and nothing forward of the principal elevation
- Anything beyond the permitted development limits, including rear extensions over 3m deep at first-floor level
- All multi-storey side extensions, and two-storey rear extensions within 7m of the rear boundary
- Homes in conservation areas, National Parks or AONBs, and all flats and maisonettes
- Properties where permitted development rights have been removed by an Article 4 direction or condition
Whichever route applies, we prepare the drawings and OS map and act as your agent with the council. Building regulations approval is needed either way: foundations, structure, insulation, drainage and fire safety are all assessed, and the completion certificate is what a future buyer or lender will ask to see. This is a general guide to the rules in England; we confirm the position for your property before any drawings are produced.
Extension drawings from completed projects
Rather than describe a drawing pack, we show real ones: planning drawings for a whole-house extension with dormer loft and remodel, building regulations and structural drawings for a first-floor extension with garage conversion, and the full technical pack for a house extension with internal remodelling, all anonymised and at reduced resolution. Browse the example extension packs.
Frequently asked
Do I need planning permission for an extension?
Not always. Under permitted development a single-storey rear extension can be up to 4m deep on a detached house or 3m on any other house, and up to 8m or 6m through the Larger Home Extension prior-approval process, within the height and coverage limits. Two-storey extensions, multi-storey side extensions and homes in conservation areas or with permitted development rights removed usually need a full application. We confirm the route for your property at the outset.
How much do house extension drawings cost?
Our fees are fixed per stage: survey, design drawings, building regulations drawings and structural design are each priced separately and agreed in writing before they start. The figure depends on the size and type of extension, your property and its location. The instant quote tool gives the exact figure for your home.
How long do extension drawings take?
Survey to an agreed proposed design typically takes one to three weeks. Planning drawings and the building regulations and structural package are each typically prepared within two to three weeks, usually in parallel. If planning permission is needed, allow around eight weeks for the council to decide.
What do building regulation drawings for an extension include?
Sections, construction details and a written specification covering the foundations, floors, external walls, structural openings, roof, insulation, drainage, ventilation and fire safety, together with the structural design package. Building control approves the work from it, builders quote like-for-like from it, and the trades work from it on site.
Do I need a structural engineer for an extension?
Yes, in almost every case. Building control will expect calculations for the foundations, any beams over new openings, the roof and any wall removed between the house and the extension. Our engineers sit alongside the designers, so the structure is designed in from the start.
Do I need to tell my neighbours?
If the extension is built on or near a shared wall or boundary, the Party Wall etc. Act 1996 requires you to serve notice on the affected neighbours before work starts. We can prepare the initial notice for a fixed fee per neighbouring property. If a neighbour does not consent, a party wall surveyor may need to be appointed.
Guides and related projects
Ready to get started?
Tell us about your project and we'll talk you through the right stages, the likely route and what to expect.