For many households, the kitchen has become the heart of the home: a place to cook, eat, work, help with homework and spend time together. That's why a kitchen extension is one of the most popular projects for homeowners across Cornwall, from terraced cottages in Camborne to family homes in Truro and coastal properties around Padstow. Done well, it can transform how a house works. This guide covers the decisions that matter most, from layout and light to planning, Building Regulations and budgeting.
Start with how you want to live
Before thinking about doors and worktops, it helps to be clear about how you'll use the space. Ask yourself:
Do you want an open-plan kitchen, dining and living area, or a kitchen-diner with a separate snug?
How many people cook at once, and do you need an island or peninsula?
Would a utility room, boot room or larder free up the main kitchen? In Cornwall, a place for wet coats, wetsuits, dogs and muddy boots is often near the top of the list.
Where does the sun come from, and when will you use the room most?
How will the new space connect to the garden?
Getting this brief right helps your designer plan a layout that works, rather than simply adding square metres.
Popular kitchen extension types
The best option depends on your house and plot:
Single-storey rear extensions are the most common, creating a large kitchen-diner opening onto the garden.
Side return extensions fill the narrow passage beside many terraced and semi-detached homes, widening a cramped kitchen.
Wraparound extensions combine rear and side to create a larger L-shaped space.
Knock-throughs remove walls between an existing kitchen and dining room, sometimes alongside a smaller extension. Our guide to removing a load-bearing wall explains what's involved.
Light, glazing and the Cornish weather
Large sliding or bifold doors, roof lanterns and rooflights can make a kitchen extension feel bright and open. In Cornwall, it's worth balancing that with the weather:
South and west-facing glazing can overheat in summer, so shading, roof overhangs and solar-control glass are worth considering.
Exposed and coastal sites need doors and windows rated for strong wind and driving rain, with careful detailing at thresholds. Our guide to weatherproofing coastal homes covers this.
Building Regulations limit glazing area unless the energy performance is made up elsewhere, so very glassy designs may need extra calculations.
Planning permission and permitted development
Many single-storey rear kitchen extensions can be built under permitted development rights, without a full planning application, as long as they meet limits on depth, height, materials and position. Larger rear extensions may be possible through the prior approval process. However, permitted development rights are reduced or removed in conservation areas, for listed buildings, for flats and maisonettes, and where earlier permissions have restricted them. Side extensions also have tighter rules in protected areas such as the Cornwall National Landscape.
It's always worth confirming the position before committing to a design. A Lawful Development Certificate from Cornwall Council can give you formal confirmation. Our guides to planning permission in Cornwall and building in an AONB or conservation area explain more.
Building Regulations, drains and structure
Whether or not planning permission is needed, a kitchen extension will normally need Building Regulations approval. That covers foundations, structure, insulation, ventilation and extraction, drainage, electrics and fire safety. A few points come up regularly:
Drains and sewers: kitchen extensions often sit over or near existing drains. Building over or close to a public sewer may need agreement from South West Water.
Steel beams: opening up the back of a house usually needs steels designed by a structural engineer.
Fire safety: open-plan layouts in some houses, particularly with loft rooms, can affect escape routes and need careful design.
Ground conditions: sloping plots, made-up ground or nearby trees may affect foundations. Our page on groundworks and foundations explains this stage.
Our Building Regulations in Cornwall guide covers the approval routes.
Budgeting for a kitchen extension
As general guidance, the overall cost depends on the size and complexity of the extension, the amount of glazing, structural work such as steels, foundations and drainage, access to the site, and the specification of the kitchen itself. Kitchen units, worktops and appliances can vary hugely in price, so it helps to set a budget for them separately from the building work. It's also sensible to allow a contingency for the unexpected, especially with older properties, and to factor in fees for design, engineering, planning and Building Control. A site visit and clear drawings are the only way to get a meaningful price.
Living through the build
Losing your kitchen is one of the hardest parts of the process. Planning a temporary kitchen, agreeing the order of work so the old kitchen stays in use for as long as possible, and keeping dust and noise under control all help. A clear programme and a single point of contact make a big difference, which is where project management helps.
Kitchen extension FAQs
Do I need planning permission for a kitchen extension?
Not always. Many single-storey rear extensions fall under permitted development, but limits apply and rights are reduced in conservation areas and for listed buildings. Check before committing.
Can I keep using my kitchen during the build?
Often for part of it. The new extension can usually be built and made weathertight before the existing back wall is opened up, keeping disruption to a shorter window.
Should I extend or convert the garage instead?
It depends on your house. A garage conversion can be quicker, while an extension gives more flexibility on layout and light.
Talk to us about your kitchen extension
Cornish Building Company designs and builds home extensions across Cornwall from our base in Wadebridge. Read our home extension guide, call us on 01208 816991, or contact us to talk through your plans.
