Do house extensions or alterations need a structural engineer?

What does a structural engineer cost?

Well, it depends on what you need them to do.  A site visit, inspection, structural calculations and indicative structural drawings suitable for Building Control Authorities approval, for one steel beam (RSJ), could cost you around £300-450 plus VAT. Many structural engineers and structural engineering firms will often have a basic list of services that they provide for alterations or extensions at a fixed fee for services required.

A structural engineer will help you to:
  • Determine if you need an architect
  • Work with your architect, if you need one
  • Prepare any structural calculations and plans needed by Building Control Authorities
  • Provide advice to you and your builder

What is the difference between a structural engineer and an architect?

An architect can help design your extension or alteration. They can make plans for planning permission and building regulations. And they’re experts in designing a beautiful home to maximise its value.

A structural engineer is concerned only with the skeleton of your build. They will help you ensure the building is safe, designed to code and built to last. Lastly, they will provide advice and support to your architect and/or builders during the project.

Why choose us


Trust our experience across 1,800+ commercial and residential projects.


We’re chartered with The Institution Of Civil Engineers and fully insured.


Our pricing and designs are cost efficient.

What is the difference between planning permission and building regulations approval?

Planning permission asks your local authority for the go-ahead to begin a construction project. They will look at the environment, your neighbour’s land and the proposed build to see if it complies with all policies and causes minimal disruption.

A building regulations application is different. It checks to see if your plans comply with national building standards. This looks at the drawings of your build to check for any flaws in the proposed structure. All extensions or structural alterations need building control authority (BCA) approval.

You generally only need planning permission if:

  • The external appearance will change outside of the Permitted Development
  • If the property is listed
  • If the property is in a protected area

A structural engineer can advise you on what kind of permissions you will need and if your BCA approval will require a full plan or simply a building notice.

Complete the form below to talk with a structural engineer in Leicester, Birmingham, Nottingham, Coventry, Northampton, Milton Keynes or nearby.

Get in touch

If you need structural calculations for your project in Leicester, Birmingham, Nottingham, Coventry, Northampton, Milton Keynes or nearby areas, we have experienced structural engineers with a wide range of knowledge and expertise. Please do not hesitate to get in touch for any assistance you require.

*Or get an instant quote

*Use this form to request a quote for structural calculations and drawings required by Building Control Authorities (and your builder) for small House Extension and/or Alterations projects. The quote should be ready within 4 hours during our standard working hours Monday – Friday 9:00 to 17:00, excluding bank holidays. For larger projects, please attach the architectural drawings and we should have the quote ready within 1-2 working days.

We are chartered under the Institution of Civil Engineers as an insured and fully qualified team of Structural Engineers.

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