Masterclass Lumina kitchen in a contemporary kitchen extension

How to plan a kitchen extension

From hiring an architect to the finishing touches, this guide has everything covered

By Rachel Ogden | 15 February 2022

Kitchen extensions offer the opportunity to create a versatile, open-plan space that can be adapted to suit changing needs. However, with a fluid variety of functions, it’s important to get the design right. Planning the build in tandem with the kitchen is key, to ensure that essential services are in the right place for your extension and that you won’t have to make compromises on the layout of your building further down the line.

rear kitchen extension with bi-fold doors, kitchen island and dining area

Photo: Roundhouse

Planning your kitchen extension

Deciding what you want your extension to include is the first step – as well as a kitchen and somewhere to eat, consider if you’d also like a living area, a desk space, extra storage or direct access to the garden.

Next, think about how you want it to look inside and what type of addition would suit your property: for example, a single- or double-storey extension, a lean-to or side return, or a rear addition. Take clippings from magazines, look online and see what has been built in your local area for inspiration.

All these factors will affect your budget, timeframe (check if you need planning permission or if it will fall under permitted development) and level of disruption. For example, lean-tos and side returns usually require less foundation work and garden space, but may need more internal structural changes, such as removing walls, disguising pillars or levelling floors and ceilings.

Once you have a rough idea of the size and type of extension, you’ll need to work out a schedule. Remember to factor in time to submit planning applications and party wall agreements with neighbours if required and find an architect and builder (the best companies are often busy), as well as time for the actual construction, which often takes between three and six months.

Read more: Kitchen extension ideas and planning tips

modern kitchen with large island, dining table and blue cabinets

Photo: Edmondson Interiors

Hire an architect

Hiring an architect is a good idea, although not essential for straightforward schemes, where a structural engineer or builder may suffice. An architect will ensure that your plans are structurally sound, take care of plumbing and electrics – which need to be considered at the planning stage – and recommend reliable trades or manage contractors.

‘If you want to employ an architect, RIBA’s website is a good place to start,’ advises Paul Schofield, commercial design manager at Apropos. ‘Asking neighbours and friends is also a great way to find an architect.’

Choose your kitchen company at the planning stage, so it can work with your architect or builder and advise on lighting, extraction and zoning the new space. The layout of your kitchen comes down to personal choice, but you may want to position cabinetry so you can enjoy garden views, socialise with the rest of the room while cooking or supervise children.

Set a budget

Costs vary by project, but the average spend is around £30,000. A two-storey extension may be more economical in terms of price per sqm. Costs for basement conversions will rise if the space needs tanking, a drainage pump or underpinning. Reworking an existing extension may not be cheaper than starting from scratch, so seek expert advice.

large rear extension with floor-to-ceiling sliding doors creating an indoor-outdoor space

Photo: Bureau de Change

Kitchen design essentials

While it’s best to plan the building before the kitchen, it’s a good idea to research suppliers and choose the company you want to use at the start of your project. Not only will it be able to suggest a programme of works, costs and concepts for the extension, but designing the kitchen sooner will minimise the chance of later alterations, such as moving doors or windows.

‘The layout is a major factor in an open-plan space; you need to think carefully about the aesthetics because your kitchen will always be on show,’ explains Graeme Smith, senior designer at 1909.

‘There’s a fine balance between a space that doesn’t look lived in and one in which there is clutter strewn across the worktops. When planning storage, think beyond the obvious cabinets and consider where to stash everyday things such as electronic devices, homework books and children’s games.’

You’ll also need to make sure that messy areas, such as sinks, aren’t directly in the line of sight, while planning in central features such as a seating area or wine cabinet.

an open-plan kitchen-diner with bi-fold doors leading to the garden

Photo: Kitchens by Holloways

Making it multifunctional

Every layout will be different depending on the space, but there are a few standard rules for zoning the room. Start by deciding where you want to eat and the view you’d like to have while cooking; it’s also useful to track the passage of the sun overhead. ‘It’s crucial that in a large room, functionality is not lost,’ advises Richard Davonport, MD at Davonport.

‘Imagine how you want to use the space and zone it so that each part has a clear function, such as distinct cooking, eating, cleaning and living areas. How they’re arranged is down to personal preference, but there should be a natural flow between the zones. For example, it’s nice for a seating or breakfast bar area to open on to the garden, so position it near the windows or doors leading outside.’

Larger rooms may need some design tricks to help define the zones. Peninsulas, different floor types and freestanding open shelves are useful for creating this visual division.

Kitchen extensions everything you need to know

Photo: Smallbone of Devizes

Maximise light

An extension will displace some of the daylight that would normally reach your original rooms, so consider supplementing it. ‘A bank of roof lights or a roof lantern is a good option,’ says Richard Witcher, partner at Witcher Crawford architects and designers. ‘Positioning the light sources nearer the back of the extension will help the sun flow into now-darker areas of the original room.’

Adding mood lighting to your kitchen, such as under-counter spots, in addition to task lighting, will ensure adequate illumination in the evenings. Full-height glass doors are a common feature of extensions, but remember that they’ll reduce the amount of wall space available for storage. Tall cupboards and islands have a large capacity in relation to their footprint, but also consider a larder and adjacent utility room to ease the storage demands on the kitchen.

kitchen with exposed brick wall, peninsula breakfast bar and high ceiling with skylights

Photo: Matteo Bianchi Studio

Kitchen extensions offer the opportunity to create a versatile, open-plan space that can be adapted to suit changing needs. However, with a fluid variety of functions, it’s important to get the design right. Planning the build in tandem with the kitchen is key, to ensure that essential services are in the right place for your extension and that you won’t have to make compromises on the layout of your building further down the line.

rear kitchen extension with bi-fold doors, kitchen island and dining area

Photo: Roundhouse

Planning your kitchen extension

Deciding what you want your extension to include is the first step – as well as a kitchen and somewhere to eat, consider if you’d also like a living area, a desk space, extra storage or direct access to the garden.

Next, think about how you want it to look inside and what type of addition would suit your property: for example, a single- or double-storey extension, a lean-to or side return, or a rear addition. Take clippings from magazines, look online and see what has been built in your local area for inspiration.

All these factors will affect your budget, timeframe (check if you need planning permission or if it will fall under permitted development) and level of disruption. For example, lean-tos and side returns usually require less foundation work and garden space, but may need more internal structural changes, such as removing walls, disguising pillars or levelling floors and ceilings.

Once you have a rough idea of the size and type of extension, you’ll need to work out a schedule. Remember to factor in time to submit planning applications and party wall agreements with neighbours if required and find an architect and builder (the best companies are often busy), as well as time for the actual construction, which often takes between three and six months.

Read more: Kitchen extension ideas and planning tips

modern kitchen with large island, dining table and blue cabinets

Photo: Edmondson Interiors

Hire an architect

Hiring an architect is a good idea, although not essential for straightforward schemes, where a structural engineer or builder may suffice. An architect will ensure that your plans are structurally sound, take care of plumbing and electrics – which need to be considered at the planning stage – and recommend reliable trades or manage contractors.

‘If you want to employ an architect, RIBA’s website is a good place to start,’ advises Paul Schofield, commercial design manager at Apropos. ‘Asking neighbours and friends is also a great way to find an architect.’

Choose your kitchen company at the planning stage, so it can work with your architect or builder and advise on lighting, extraction and zoning the new space. The layout of your kitchen comes down to personal choice, but you may want to position cabinetry so you can enjoy garden views, socialise with the rest of the room while cooking or supervise children.

Set a budget

Costs vary by project, but the average spend is around £30,000. A two-storey extension may be more economical in terms of price per sqm. Costs for basement conversions will rise if the space needs tanking, a drainage pump or underpinning. Reworking an existing extension may not be cheaper than starting from scratch, so seek expert advice.

large rear extension with floor-to-ceiling sliding doors creating an indoor-outdoor space

Photo: Bureau de Change

Kitchen design essentials

While it’s best to plan the building before the kitchen, it’s a good idea to research suppliers and choose the company you want to use at the start of your project. Not only will it be able to suggest a programme of works, costs and concepts for the extension, but designing the kitchen sooner will minimise the chance of later alterations, such as moving doors or windows.

‘The layout is a major factor in an open-plan space; you need to think carefully about the aesthetics because your kitchen will always be on show,’ explains Graeme Smith, senior designer at 1909.

‘There’s a fine balance between a space that doesn’t look lived in and one in which there is clutter strewn across the worktops. When planning storage, think beyond the obvious cabinets and consider where to stash everyday things such as electronic devices, homework books and children’s games.’

You’ll also need to make sure that messy areas, such as sinks, aren’t directly in the line of sight, while planning in central features such as a seating area or wine cabinet.

an open-plan kitchen-diner with bi-fold doors leading to the garden

Photo: Kitchens by Holloways

Making it multifunctional

Every layout will be different depending on the space, but there are a few standard rules for zoning the room. Start by deciding where you want to eat and the view you’d like to have while cooking; it’s also useful to track the passage of the sun overhead. ‘It’s crucial that in a large room, functionality is not lost,’ advises Richard Davonport, MD at Davonport.

‘Imagine how you want to use the space and zone it so that each part has a clear function, such as distinct cooking, eating, cleaning and living areas. How they’re arranged is down to personal preference, but there should be a natural flow between the zones. For example, it’s nice for a seating or breakfast bar area to open on to the garden, so position it near the windows or doors leading outside.’

Larger rooms may need some design tricks to help define the zones. Peninsulas, different floor types and freestanding open shelves are useful for creating this visual division.

Kitchen extensions everything you need to know

Photo: Smallbone of Devizes

Maximise light

An extension will displace some of the daylight that would normally reach your original rooms, so consider supplementing it. ‘A bank of roof lights or a roof lantern is a good option,’ says Richard Witcher, partner at Witcher Crawford architects and designers. ‘Positioning the light sources nearer the back of the extension will help the sun flow into now-darker areas of the original room.’

Adding mood lighting to your kitchen, such as under-counter spots, in addition to task lighting, will ensure adequate illumination in the evenings. Full-height glass doors are a common feature of extensions, but remember that they’ll reduce the amount of wall space available for storage. Tall cupboards and islands have a large capacity in relation to their footprint, but also consider a larder and adjacent utility room to ease the storage demands on the kitchen.

kitchen with exposed brick wall, peninsula breakfast bar and high ceiling with skylights

Photo: Matteo Bianchi Studio

Create a seamless scheme

Your extension doesn’t have to be exactly the same style as your home, but there should be a sense of cohesion. This is important if you’ve created an open-plan kitchen, with a cooking and living space in one. If there are large areas of glass, the extension may be brighter than the rest of the house, so consider this when choosing materials and colours. Many kitchen designs have more of a furniture feel and come in wood veneers and muted tones, so are ideal in an open-plan room or one that flows from a more traditional interior.

Another way to unify the extension and the rest of your home is with flooring, lighting and paint – using the same materials or colours will ease the transition. Linking an extension with an outside area is popular and often achieved with glazed doors.

‘When planning the space, think about where the doors will be installed and the effect they will have on the view,’ suggests Peter Watkins, general manager at Centor Europe. ‘For example, bi-fold doors provide a seamless connection and unrestricted access to outside, while sliding doors may be a better choice if you expect to have them closed the majority of the time.’

A final consideration is how you are going to dress glass doors. Window treatments provide privacy, insulation and a softer aesthetic, plus they will prevent your glazing from looking like an expanse of black at night.

A step by step guide to kitchen extensions8

Photo: Michael Wright Kitchens and Interiors

Finishing touches

As your kitchen-diner will be on display, getting the details right is essential. Consider hiding power points in a cupboard with a tambour door, or adding pop-up sockets, so the lines of your design remain uninterrupted. Similarly, integrated appliances and a downdraft extractor that recesses into the worktop will make the space feel less utilitarian when the kitchen isn’t in use.

The materials you choose can also help the room to work as one. ‘To create a unity of design within the space, consider a graduation in height from the kitchen, through an informal dining zone to media units in the living area in one continuous run, with a single finish for surfaces and cabinets,’ suggests Michael Wright, founder of Michael Wright Kitchens and Interiors.

Alternatively, introduce a contrasting top to differentiate individual zones. A wooden worksurface to delineate the dining area at the end of a stone or laminate peninsula has the additional advantage of being warmer, both on the eye and to the touch.’

A step by step guide to kitchen extensions8

Photo: Sybaris Interiors

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