Frequently Asked Questions

Every project is different, but as a guide, here is a typical breakdown of professional and statutory fees for a straightforward single-storey extension:

Design & planning stage

• Architectural design & drawings: ~£600

• Planning application statutory fee: ~£528
  (or less if a Lawful Development Certificate is used for permitted development)

Technical design & approvals

• Detailed Building Regulations drawings: ~£700–£1,000 (depending on complexity)

• Structural engineer (if required): ~£500–£1,000

• Building Control application & inspections: ~£1,000

Possible additional costs (project dependent)

• Build Over Agreement (if building near or over a public sewer)

• Party Wall surveyor fees (if an award becomes necessary and is contested)

• Specialist surveys (drainage surveys, site investigations, etc.)

Typical total (excluding construction costs):
For a standard single-storey extension, professional and statutory fees commonly fall in the range of £2,800 – £4,000, depending on complexity and site constraints.

Please note that this excludes construction costs, which vary widely depending on size, specification, and site conditions. I'm always happy to provide a clearer estimate once I understand your project.

Timescales vary depending on the complexity of the project and how quickly decisions are made, but a typical single-storey extension follows this general timeline:

Design & planning stage – 3–6 weeks

• Initial survey, design development, and preparation of drawings.

• Timescales depend on how quickly feedback and approvals are provided.

Planning / Lawful Development Certificate

• Planning application: 8 weeks (statutory determination period)

• Lawful Development Certificate: up to 8 weeks, often quicker

Technical design & Building Regulations – 3–6 weeks

• Detailed drawings, structural engineering input (if required), and Building Control submission.

Typical total pre-construction timeframe:
From initial appointment to being ready to start on site, most single-storey extensions take 10–16 weeks, depending on planning requirements and project complexity.

Once on site, construction usually takes 8–12 weeks, depending on size, specification, and contractor availability.