Planning and Building Regulations Drawings Explained

What a planning set contains

A planning set tells the council where the site is, what is there now and what you propose. The exact list is set by each council's validation checklist, called the local list, but a householder set usually holds these drawings.

1. Location plan. The site on a map, outlined in red, with other land you own in blue.
2. Site or block plan. The house, its boundaries and the extension in relation to them.
3. Existing and proposed floor plans. Every floor that changes.
4. Existing and proposed elevations. Each side of the house that changes.
5. Sections and roof plans. Where height or the roof changes.
6. Supporting documents. Whatever the local list asks for, such as a design and access statement or a heritage statement.

Every drawing must be to a recognised scale and labelled. The plans, elevations and sections must also match each other, or the application can be rejected before anyone looks at the design.

What building regulations drawings add

Building regulations drawings take the approved design and show how it will be built. They are more technical and more detailed than a planning set.

1. Construction details. Walls, floors and roofs layer by layer, with insulation and damp-proofing.
2. Structure. Beams, columns and foundations, with a structural engineer's calculations.
3. Fire safety. Escape routes, fire doors and protected stairs, often critical in a loft.
4. Drainage and ventilation. New runs, connections and how rooms are ventilated.
5. Specifications. The materials and standards the builder must use.

Approval comes from your council's building control or a private registered building control approver. A full plans application has the drawings checked before work starts. Lewisham, for example, decides within five weeks unless the applicant agrees an extension.

These drawings also become the builder's working information. On the RIBA Plan of Work, planning applications generally go in at the end of Stage 3, and the Building Regulations application during Stage 4.

Who can draw planning and building regulations drawings

Anyone can prepare the drawings. There is no legal requirement to use an architect, and many applications are drawn by architectural technologists, designers or a builder's own design team.

What the law protects is the title. Under section 20 of the Architects Act 1997, using the title architect in business without being on the Architects Register is a criminal offence. Check the register if someone uses the title.

What matters more is accuracy and coordination. The person who draws the planning set should also prepare, or closely coordinate, the building regulations drawings and the engineer's design. A gap between the two sets usually surfaces on site, as a redesign.

How long planning and building regulations approval take

The council has 8 weeks to decide most householder and minor applications. The clock starts the day after a valid application is received, and a longer period can be agreed in writing. Our guide to how long planning permission takes covers what councils actually achieve.

Building control usually decides a full plans application within five weeks, or a little longer by agreement. The two can run in parallel once the design is fixed, which keeps building regulations off the critical path.

The drawings themselves take longer than either approval. A measured survey, design options and your decisions come first, and on a London house the brief can be the slowest part.

What drives the cost of planning drawings

Drawings are usually priced as a fixed fee per set, or as part of a percentage fee. The HomeOwners Alliance guide for 2026, citing Checkatrade, puts single-storey extension planning drawings at £1,000 to £2,500, and two-storey at £2,000 to £3,500.

For building regulations and construction drawings, the same guide quotes £3,000 to £5,000 for a single-storey extension. A double-storey extension is £5,000 to £7,000. These are national figures.

Five things move the number:

1. Size and complexity. More floors, more drawings.
2. The building. A listed house or a conservation area calls for more information.
3. The survey. An accurate measured survey costs money but saves redrawing.
4. Revisions. Each round of changes, yours or the council's, is new work.
5. Engineering. Structural calculations are usually priced separately.

The council's fee is extra: £548 for a householder application in England since 1 April 2026. Our guide to architect fees in the UK sets out the fee models stage by stage.

Common reasons councils reject drawings

Most applications that fail at the first hurdle fail on paperwork, not design. Lambeth Council lists ten common reasons an application is marked invalid.

An invalid application does not start the 8-week clock. Ask whoever draws your scheme to check it against your council's local list before it is submitted.

How we prepare drawings for London homes

Many home projects stall between the planning drawings and the builder's price. When the design and the build sit in two firms, the drawings are priced after approval. If they come in over budget, redesign follows.

Our design team and our construction team work in one company. Each option is priced as it is drawn, and the building regulations drawings become the information our own trades build from. At Herbert Crescent in Knightsbridge, each layout, finish and fixing was agreed from drawings and samples before it was built.

Planning an extension? Our guide to the architect for a house extension covers what to expect. When you are ready, book a free design consultation and we will reply the same working day.