Open-Plan Kitchen-Diner Cost: Knocking Through and Fitting Out

Knocking through a wall between a kitchen and dining room to create an open-plan space typically costs £500-£1,500 if the wall is non-load-bearing, or £3,000-£8,000+ if it's load-bearing and needs a steel beam (RSJ) to support the floors and roof above. That's on top of whatever you spend fitting out the kitchen itself — this figure is purely for the structural opening-up work.

What decides the price

The single biggest factor is whether the wall is load-bearing. A non-load-bearing partition wall is a relatively straightforward job: demolition, disposing of rubble, and making good the floor, ceiling and adjoining walls. A load-bearing wall is a different scale of project entirely — it needs a structural engineer to calculate the correct beam size, temporary propping while the old wall comes out, the steel beam itself supplied and installed, padstones or columns to carry the load down to the foundations, and Building Control sign-off at every stage.

• Non-load-bearing wall removal: roughly £500-£1,500, mostly labour, skip hire and making good.
• Load-bearing wall removal with a single steel beam: roughly £3,000-£6,000, including the structural engineer's calculations, the beam itself, and installation.
• Longer spans or more complex loading (e.g. a chimney breast above, or a wall supporting a loft conversion): can run to £8,000 or more.

Beyond the wall itself, budget for knock-on costs that are easy to forget: matching or replacing flooring so it runs continuously across the new open space, replastering and redecorating both rooms, and potentially rerouting electrical circuits or radiators that were on the wall you've removed. If the kitchen's extractor fan needs to duct further to an external wall once the layout changes, that adds cost too.

Do you need planning permission or building regulations approval?

Removing an internal wall inside your own home is usually permitted development and doesn't need planning permission — but that's not guaranteed in every case (leasehold flats often have restrictions written into the lease, for example), so it's worth a quick check with your local council if you're unsure. Building regulations approval, on the other hand, is required whenever you remove a load-bearing wall, regardless of planning permission — see our guide on building regulations for a kitchen renovation for what that involves and what it typically costs.

How long does the work take?

A straightforward non-load-bearing wall removal, including making good, is often a 2-3 day job on its own. A load-bearing wall removal typically takes longer once you factor in the full sequence: the structural engineer's survey and calculations (which can take one to two weeks to arrange, depending on their workload), submitting the calculations to Building Control, installing temporary propping, removing the wall, fitting the steel beam, and then making good the surrounding plaster, flooring and decoration. Altogether, a load-bearing knock-through is commonly a two-to-three week process from the structural engineer's first visit to a finished, redecorated opening — longer if it's combined with a wider kitchen renovation or an extension.

Steel beam sizes and visibility

One detail worth planning for early: a structural steel beam needs a certain depth to span the opening safely, and that depth is dictated by the engineer's calculations, not personal preference. In many cases the beam can be boxed in flush with the ceiling so it's barely noticeable, but for a wide opening or a longer span, the beam may need to sit slightly proud of the ceiling line, which affects the finished look and is worth discussing with your structural engineer and builder before work starts, rather than being a surprise partway through.

Common mistakes

• Not getting a structural engineer involved early. Guessing at a beam size, or trusting a builder's estimate without proper calculations, is a genuine safety risk and can also mean expensive rework if Building Control rejects it.
• Forgetting ventilation. An open-plan kitchen-diner needs the extractor to actually work across the bigger space — a fan sized for a small enclosed kitchen may struggle once the room effectively doubles.
• Underestimating the making good costs. Patching plaster, matching flooring, and repainting both rooms often costs more than people expect relative to the structural work itself.

If you're planning the kitchen fit-out alongside the knock-through, it's worth reading our guide to replumbing a kitchen too, since an open-plan reconfiguration often means moving the sink or dishwasher to a new position.

For a full breakdown of fitted-kitchen costs on top of this structural work, see our UK kitchen renovation cost guide, and for how long the whole project is likely to take, see how long a kitchen renovation takes.

Related reading: moving your kitchen to a different room.