Knocking through to create an open-plan kitchen, dining and living space is one of the most popular home improvements in Cornwall. It can transform a dark, cellular layout into a bright, sociable space and make better use of the light and views. But if the wall you want to remove is load-bearing, the work needs proper structural design, approval and careful execution. This guide explains what's typically involved, from the structural engineer and steel beams to Building Control and the extra care needed in older Cornish stone and cob homes.
Is the wall load-bearing?
A load-bearing wall supports something above it, such as floor joists, another wall, the roof or a chimney. Clues include walls that run at right angles to the floor joists, walls directly beneath other walls upstairs, and walls in the middle of the house that line up with the ridge. In many older homes, internal walls carry more load than you might expect, and some apparently lightweight partitions have been loaded over time as the building has settled.
Appearance alone isn't a reliable guide. The safest approach is to have a builder and a structural engineer inspect the wall before you plan anything, often opening up a small area of floor or ceiling to see how the structure works.
The role of the structural engineer
If the wall is load-bearing, a structural engineer will usually design how the loads will be carried once it's gone. This typically includes:
Calculations for the beam size and type, often a steel beam, but sometimes timber, glulam or reinforced concrete depending on the situation.
Bearings, such as padstones or posts at each end of the beam, to spread the load into the walls below.
Foundations, as the new point loads may need checking and, in some cases, new or improved foundations.
Temporary works, showing how the structure will be supported while the wall is removed.
These calculations and drawings are normally needed for Building Regulations approval, and they give your builder a clear specification to work from.
Building Regulations and Building Control
Removing a load-bearing wall is structural work, so it will normally need Building Regulations approval, either by a full plans application or a building notice, depending on the project. A Building Control inspector will usually want to see the steel and its bearings before they're covered up.
Fire safety is also important. Opening up the ground floor can affect escape routes, particularly in homes with rooms on two or more upper floors, such as houses with loft conversions, where a protected stairway may be required. Steel beams may need fire protection, for example with fire-rated boarding or intumescent paint. Your designer and Building Control will confirm what's needed for your home. Our guide to Building Regulations in Cornwall explains the process.
Internal alterations to a house don't usually need planning permission, but listed buildings are different. Removing or altering internal walls in a listed building normally needs listed building consent from Cornwall Council, and in some cases it may not be acceptable at all.
How the work is typically carried out
A well-run knock-through usually follows a careful sequence:
Preparation, including protecting floors and furniture, isolating any services in the wall and checking for asbestos in older properties.
Temporary support, using adjustable steel props and needles to carry the floor or wall above while the wall is removed.
Removing the wall in a controlled way, often in stages.
Installing the beam on its padstones or posts, packing it tightly and checking it's level.
Inspection by Building Control before the steel is boxed in.
Making good, including plastering, fire protection, flooring and decoration.
The dust and disruption can be considerable, so it's worth planning the work around how you'll live in the house, especially if the kitchen is affected.
Older Cornish stone and cob homes
Many Cornish homes are built with thick stone or cob walls, and these need a different approach from modern masonry:
Stone walls are often rubble-filled and can vary in quality within the same wall. Forming openings may need careful needling, new lintels and well-built bearings, and the engineer may ask for opening-up works before finalising the design.
Cob walls are made of earth and straw. They can be strong when kept dry, but they're vulnerable to moisture and to large new openings. Alterations to cob usually need specialist advice and a cautious, breathable approach.
Chimney breasts are common in older homes. Removing a chimney breast also needs structural support for any masonry left above, and Building Regulations approval.
Party walls in terraced and semi-detached homes may be affected if a beam bears into a shared wall, in which case the Party Wall Act may apply. See our Party Wall Act guide.
Our page on stone, rendering and lime work and our guide to renovating an old Cornish cottage explain why breathable materials matter in these buildings.
Making the most of open-plan living
A good open-plan layout is about more than removing a wall. It's worth thinking about:
Zoning the space for cooking, eating and relaxing.
Heating, as a larger open space may need a different heating layout.
Acoustics and cooking smells, with a good extractor and soft finishes.
Light, as knocking through often works well alongside roof lights or larger glazed doors.
Many homeowners combine a knock-through with a home extension or wider property renovation, which can be more efficient than carrying out the work in separate phases.
Load-bearing wall FAQs
Do I need planning permission to remove an internal wall?
Usually not for a house that isn't listed, but Building Regulations approval is normally needed if the wall is load-bearing. Listed buildings generally need listed building consent.
How long does it take to remove a load-bearing wall?
The structural work itself can often be done in days, but design, approvals, ordering steel and making good add to the overall timescale.
How much does it cost?
It depends on the span, the loads involved, the construction of the house and how much making good is needed. Costs are best assessed after a site visit and engineer's design.
Talk to us about knocking through
If you're thinking about creating open-plan living anywhere in Cornwall, we can help you plan the work with your engineer and Building Control. Call us on 01208 816991 or contact us to talk through your plans.
