What Does a Structural Engineer Do? A Simple Guide for UK Homeowners
A structural engineer checks whether your home is safe when you remove, change or build anything that carries weight. They work out how strong your walls, floors, roofs and foundations are, and they design the steel beams or supports you need when you change the structure. If you’re planning a wall removal, a loft conversion or an extension, you’ll almost always need a structural engineer.
What a Structural Engineer Actually Does
A structural engineer looks at how loads move through your home. Loads are things like floors, walls, furniture, people and the roof. Their job is to keep everything safe and stable.
Checking if a wall can be removed
They check whether the wall supports the floor or roof above. If it does, they design the steel beam to replace it. See our guide on remove a load bearing wall.
Designing steel beams and supports
They size RSJs for wall removals, openings, extensions and loft conversions. This includes connections and padstones.
Making sure a home extension is safe
They check the new walls, roof, beams and foundations. They work out how loads move from the new structure into the old one.
Assessing loft conversions and roof loads
They design the ridge beam, floor joists and steel supports needed to turn a loft into a safe room. Read more about loft conversion beams.
Foundation checks and floor design
They check whether the soil and ground can carry the new loads. They may design foundations or strengthened floors.
When You Need a Structural Engineer
Removing a load bearing wall
Any wall that carries weight needs calcs and a beam. Building Control will ask for this.
Adding a loft conversion
You’ll need calcs for the steel ridge, new joists and structural floor.
Building a home extension
Even a simple single-storey extension needs structural design for the roof, beams and foundations.
Installing steel beams, columns or goalposts
Any steel support must be designed and approved.
Damage, cracks or sagging floors
A structural engineer diagnoses the cause and provides advice or repair design.
What a Structural Engineer Provides
Structural calculations
These prove the beam or support is safe. Building Control requires them.
Structural drawings
Clear drawings showing beams, padstones, bearings and dimensions.
Building Control documents
You need these for sign-off and for future home sales.
Site inspection
Only needed for complex work or damage reports.
How Much a Structural Engineer Costs in the UK
The price depends on the job. For a full breakdown, see our structural engineer cost page.
Typical fees (rough guide)
- Wall removal: £250 to £450
- Loft conversion package: £450 to £900
- Home extension: £500 to £1,200
- Crack inspection: £200 to £300
What affects the price
- Number of beams
- Size of the opening
- Complexity
- How clear your photos and plans are
- Location in the UK
Why prices vary
Small firms charge less. Larger consultancies include admin and overheads.
How to Choose the Right Structural Engineer
Qualifications to look for
Chartered (CEng), Incorporated (IEng), or experienced degree-qualified engineers.
Experience that matters
Choose someone who regularly designs:
- wall removals
- loft conversions
- extensions
- RSJs
Questions to ask
- How quickly can you deliver?
- Do you include drawings?
- Do you charge per beam or per project?
What the Process Looks Like (Step by Step)
- You send photos and a floor plan
- Engineer checks loads and structure
- Beams and supports are calculated
- Drawings are issued
- Builder installs beams
- Building Control signs off
FAQs
Do I always need Building Control?
Yes if you remove walls, convert a loft, or build an extension. For official guidance, check the Building Regulations overview (Planning Portal).
How long do structural calcs take?
Most jobs take 24–48 hours once info is clear.
Can an architect replace a structural engineer?
No. Only a structural engineer can design beams and confirm safety.
Do I need a site visit?
Not always. Clear photos and measurements are often enough.
Can you remove a wall without steel?
Only if it’s non-load-bearing.
Conclusion
A structural engineer gives you the calculations and drawings needed to make changes to your home safely. Whether it’s a wall removal, a loft conversion or an extension, the engineer makes sure the structure can carry the new loads and passes Building Control.
Get Your Structural Calculations
If you need fast and clear structural calculations for your project, contact SECalcs and we’ll guide you through every step.