The short answer
An open-plan kitchen-diner usually means knocking through a wall, which often involves structural work (a steel beam), Building Regulations approval and extra cost on top of the kitchen itself. Removing a load-bearing wall needs a structural engineer and a building control sign-off; the beam and works typically add £1,500–£5,000+ before the kitchen. Plan for ventilation, heating and noise — an open space carries cooking smells and sound further. See the pillar cost guide for context.
Open-plan kitchen-diners are hugely popular for family living and entertaining, but they are more than a kitchen project — they usually involve building work. This guide covers the structural, regulatory and practical points to weigh before you knock through, with realistic 2026 cost pointers.
Open-plan at a glance
- Knocking through often structural
- Steel beam / works £1,500–£5,000+
- Needs Building Regulations approval
- Plan for ventilation and heating
- Consider noise and smells
- Usually no planning permission for internal work
Structural work and the steel beam
If the wall you want to remove is load-bearing, it must be replaced with a suitable support — usually a steel beam (RSJ) — designed by a structural engineer and installed correctly. This is the single biggest cost and complexity in going open-plan. Even a non-load-bearing wall needs care for services running through it. A structural engineer's calculations and a building control inspection are part of the job; never remove a structural wall without them.
| Element | Typical cost | Notes |
|---|---|---|
| Structural engineer | £400–£1,000 | Calculations for the beam |
| Steel beam & install | £1,500–£4,000+ | Depends on span and access |
| Building control | £300–£800 | Inspection and sign-off |
| Making good | £500–£2,000 | Plaster, floor, decoration |
Building Regulations and permissions
Removing or altering a load-bearing wall is notifiable building work and must comply with Building Regulations, with building control inspecting the structural work. Internal open-plan work does not usually need planning permission, though listed buildings and some flats have extra rules. New electrical circuits are notifiable under Part P, and a gas hob relocation needs a Gas Safe registered engineer. See our Building Regulations and planning permission guides for detail.
Heating, noise and zoning
A larger combined space takes more to heat, so check the heating can cope — you may need an extra radiator or underfloor heating. Noise also travels further, so cooking, the dishwasher and the TV all share the space; soft furnishings, rugs and quieter appliances help. Many people zone the space with an island, a change of flooring or lighting so the kitchen and dining areas feel distinct without a wall. See island costs.
Is open-plan worth it?
Open-plan can transform how a home feels and is popular with buyers, but it is a bigger, costlier project than a like-for-like kitchen and removes a room you can shut away. Weigh the structural cost, the loss of a separate room, and the ventilation and heating implications against the sociable space you gain. This is general information; whether open-plan suits your home depends on its structure, your budget and how you live. Always use a structural engineer and building control for any wall removal.
Compare kitchen quotes
Open-plan projects combine building work and a kitchen. Compare itemised quotes from specialists who can coordinate both.
Frequently asked questions
Do I need permission for an open-plan kitchen-diner?
Internal open-plan work does not usually need planning permission, but removing a load-bearing wall is notifiable building work that must comply with Building Regulations, with building control inspecting the structural work. Listed buildings and some flats have extra rules.
How much does knocking through cost?
Removing a load-bearing wall typically adds £1,500–£5,000 or more before the kitchen, covering a structural engineer, a steel beam and its installation, building control and making good. The cost depends on the span, access and the amount of making good needed.
Do I need a structural engineer?
Yes, if the wall is load-bearing. A structural engineer designs the supporting beam and provides the calculations building control needs. Never remove a structural wall without engineer's calculations and building control sign-off.
How do I deal with cooking smells in an open-plan kitchen?
A good extractor — ideally ducted to outside — is essential because smells and moisture travel further in an open space. Adequate ventilation is also a Building Regulations requirement, so plan extraction and any make-up air at the design stage.
Sources & further reading
- GOV.UK / Building Regulations — structural work, ventilation and electrical safety
- KBSA (Kitchen Bathroom Bedroom Specialists Association) — guidance on open-plan kitchen design
- Gas Safe Register — rules for relocating gas hobs
- TrustMark — finding and checking registered tradespeople
This is general information, not advice for your specific property or installation. Always use a structural engineer and building control for any wall removal. Costs vary with structure, span and region.