Two-storey extension plans and drawings in Oxfordshire

Oxfordshire at a glance

Nation: England
Price region: South East England
Postcode areas: OX, RG, SN
Towns covered: 13 listed below, plus surrounding villages
Site visits: Free, no obligation

What a set of extension plans involves

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.

Oxfordshire towns we list: Oxford (OX1), Banbury (OX15), Abingdon (OX13), Bicester (OX6), Didcot (OX11) and Witney (OX7). Every other address in Oxfordshire 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

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.

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.

How we work in Oxfordshire

Visit and first ideas
One of our team visits your house in Oxfordshire, 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.
Technical design
We prepare the building regulations drawings, structural calculations and specification so the build price can be fixed.
Finish and certify
Second fix, plastering and making good, then building control's final inspection and the completion paperwork.

Towns we cover in Oxfordshire

Two-storey extension plans and drawings in Oxfordshire: questions

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.

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.

Neighbouring areas

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