What does a structural engineer do?
A structural engineer assesses the structural elements of a building and provides calculations for any changes that affect them. For home improvement projects, this typically means calculating the size of steel beams needed to carry loads when walls are removed, designing foundations for extensions, and specifying floor and roof structures for loft conversions.
When is a structural engineer required?
You will need a structural engineer for: removing or partially removing a wall (to determine whether it is loadbearing and calculate the correct beam size); house extensions (for foundations, beams, and structural connections); loft conversions (floor strengthening, roof structure changes, dormer construction); underpinning or subsidence repairs; and garage conversions where the garage door opening is removed.
Do I find a structural engineer or does my builder?
Either approach works. Many builders have a structural engineer they work with regularly, which can simplify communication. You can also appoint your own independently — the SCSE (Structural and Civil Standards for Engineering) website has a register of qualified engineers. For Building Regulations purposes, independent calculations may be required.
What does a structural engineer cost?
For residential projects, structural engineer fees typically range from £500 to £2,000 depending on the complexity of the project. A simple RSJ (steel beam) calculation for a wall removal costs £300–£600. Full extension or loft conversion calculations cost £800–£2,000. These fees are generally worth every penny — an incorrectly sized beam is both dangerous and very expensive to fix.