Steel beam calculations for removing a load-bearing wall
Structural design for removing all or part of a load-bearing wall, usually with a new steel beam, padstones and temporary propping.
About this service
Knocking through between a front and back reception, or opening a kitchen into a dining room, is one of the most popular alterations in London homes. Whether it is safe depends entirely on what the wall is holding up. A wall might carry floor joists, another wall above, part of a chimney, or the roof through struts. Our load-bearing wall opening design works out exactly what the wall supports and designs a new structure to carry it.
Homeowners usually come to us once they have settled on a layout, or once their builder has said a beam is needed. Builders also ask us directly when they need a beam size to price a job, and landlords use the service when reconfiguring flats. If you are unsure whether a wall is load-bearing at all, our guide to removing a wall explains the signs.
In period London houses, internal walls are often more important than they look. The spine wall in a Victorian terrace usually carries floors on both sides and sometimes the roof. Upper walls may stand directly on it, and in converted houses the wall can carry flats above. The answer cannot be read from floor plans alone, so we check the loads through the building, floor by floor, down to the ground.
Designs go through our three-step quality control process, with final sign-off by our Head of Engineering. We send the calculations to Building Control and handle their queries on your behalf, and your builder gets a marked-up drawing to work from. Fees start from £400 + VAT, and the fixed fee is confirmed in writing before any work starts.
When you need it
- You want to knock through to create an open-plan space
- Building Control needs calculations for a wall removal
- Your builder needs a beam size
What's included
- Check of the loads carried by the wall
- Beam and padstone design
- Temporary propping guidance
- Calculations and a marked-up drawing
How it works
- Look at the wall in contextWe inspect the wall and the floors above, or review photos and drawings where a visit is not needed. We establish which way the joists run, what stands above, and where the beam ends will bear.
- Trace the loadsWe calculate the loads from floors, walls and roof that pass through the section being removed, including point loads from upper walls or chimneys that are easy to miss.
- Design the beam and bearingsWe size the steel beam and design padstones or posts at each end so loads reach the foundations safely. Where bearings are poor, we may specify new piers or posts on new pad foundations.
- Plan the proppingWe set out how the structure above is held while the wall comes out, including needle positions and prop spacing, so the builder works in a safe order.
- Check, issue and submitAfter our three-step quality control and final sign-off by the Head of Engineering, we issue the package to you and your builder and send it to Building Control.
What you receive
Steel beam or concrete lintel?
For narrow openings such as a new doorway, a precast concrete or steel lintel is often enough. Wider openings, or those with a floor or wall bearing on them, almost always need a steel beam. Steel can sometimes be raised into the floor depth with the joists hung from it, which gives a flat ceiling. A downstand beam is simpler to install but leaves a visible bulkhead below the ceiling.
Bearings are where problems usually arise. Soft old brickwork, rubble-filled walls or a fireplace opening below can make a standard padstone inadequate, and sometimes the load has to go into a new post and foundation. Building Control will usually want to see the bearings before they are plastered over.
If the beam bears on a party wall, notice under the Party Wall etc. Act 1996 will normally be needed. If a wall has already been removed without a design, our retrospective structural assessment can check what was installed and whether it is adequate.
Not included
- Building Control fees
Projects that used this service
Frequently asked questions
How do I know if a wall is load-bearing?
Clues include floor joists running across the wall above, another wall directly above on the next floor, a chimney breast nearby, or solid brick rather than stud construction. Spine walls in terraced houses are usually load-bearing. None of these is certain, and even a hollow stud wall can carry load. An engineer's inspection is the reliable way to confirm.
Do I need Building Control approval to remove a load-bearing wall?
Yes. Removing a load-bearing wall is structural work under Building Regulations Part A, so you need Building Control approval and an inspection of the beam and bearings before they are covered. Calculations from a structural engineer are the normal way to show compliance. We send ours to Building Control and respond to their questions.
How much bearing does a steel beam need at each end?
There is no single figure. Bearing length depends on the load, the beam size and the strength of the masonry underneath. Most domestic beams sit on a concrete or engineering brick padstone that spreads the load, but the padstone size and bearing length come from the calculation rather than a rule of thumb. Weak brickwork may need a larger padstone or a new post.
Can I remove a wall that supports the roof?
Usually yes, but the design is more involved. Some internal walls carry struts from roof purlins, so removing them means the roof load must be picked up by a new beam or a different support arrangement. We trace the load from the roof down and design the replacement, which may include steel in the loft as well as at the opening.
What does a structural engineer charge for a wall removal?
Our load-bearing wall opening design starts from £400 + VAT. The fee depends on how many openings there are, what sits above them, and whether a site visit is needed. It is fixed and confirmed in writing before any work starts, and includes sending the calculations to Building Control.