Kitchen diner extension ideas to plan, budget and build

blue kitchen with white work tops and dining area in extensions
(Image credit: British Standard by Plain English)

Adding a kitchen diner extension to an existing home will add space, value and, if planned and designed correctly, a functional yet versatile room for the whole family to interact in.

Before you begin your adventure building an extension, carefully explore the different styles and designs that are available out there, and consider how they will suit the property.

Lavish open-plan kitchen diners might be the envy of all, but a small, well-thought out extension can be just as effective and deliver the same amount of impact.

Take a look below to find ideas to inspire you, expert advice to follow and find out what the first steps are in planning a kitchen diner extension.

Kitchen diner extensions: Before you begin

Creating an open-plan kitchen diner can completely change the way in which you interact in the home but the process will be challenging and often stressful (especially where savings are involved) — put your best foot forward with some simple steps to planning your new extension and kitchen design

"A brief discussion with your planning department won’t harm as a first step, but in most cases, you will need to consult with an architect to produce initial drawings for planning (planning takes around 8 weeks — if you have cooperative neighbours)," explains William Durrant, owner of Herringbone Kitchens. "Getting a recommendation for an architect is crucial. In some cases, you won’t need an architect and you can work with an architect technician or a surveyor.   

"The kitchen is normally the reason for the extension, so you want to make sure it can accommodate everything you are dreaming of. It is a good idea to get an initial design and quote from your kitchen company early in the planning process, after you have planning permission ideally. This ensures you won’t run into design limitations further down the line."

"The kitchen really is the heart of the home. If you can scale up and add versatility to the space, incorporating dining, entertaining and home working, that can only be a good thing," adds Adrian Bergman, design manager at Plain English Design. "When designing a kitchen extension there are quite a few elements that need to come together in order to make it a successful project. The design brief and involving your kitchen designer at the early stages are incredibly important."

1. Collect inspiration to create a great brief

black clad kitchen and diner extension with large sliding doors

This kitchen dining extension features a modern black cladding outside the light, fresh interiors.  (Image credit: Herringbone Kitchens)

“It’s important to gather inspiration prior, so you have a clear idea on the non-negotiables," explains Al Bruce, founder of Olive & Barr. "While aesthetics are important, ask yourself what you’ll be using the space for, how many people are in the household and what proportion of your everyday you’ll be spending there. 

"Those answers will help you determine the flow of the room as well as the materials. For example, materials that are hardwearing are better in areas of high traffic like the kitchen.

"Next, gather a list of suppliers that offer a similar design to the style you’re trying to achieve," Al adds. "The benefit of speaking with a designer is they’ll be able to make your dreams a reality, with extra details you possibly wouldn’t have thought of. They should take into consideration both form and function, making sure your kitchen works for the whole household."

2. Determine the right layout for your lifestyle

modern kitchen diner extension with rooflights and polished concrete flooring

Despite being large in foorprint, this kitchen diner extension uses clever zoning techniques to break up the space.  (Image credit: Chris Snook)

Look into house extension ideas to create a layout shape in your head of how the new extension will flow from the existing house and if any walls will need knocking through (or building from scratch). 

"Broken plan kitchen layout ideas have remained a popular choice, they are still as aesthetically pleasing as an open plan kitchen but with added functionality," Al Bruce comments. "Better yet, it suits to both small and awkwardly proportioned rooms. This versatile layout is ideal for zoning areas of the kitchen, achieved by creating partitions, for example, a freestanding breakfast bar, open shelving, and panelled glass doors. With multifunctional living being a priority for many, a broken plan allows for both work and play, with the option of a little privacy when needed."

This will also inform the shape of the open plan kitchen itself, be it with a practical island, a L-shaped design or traditional farmhouse style with a practical preparation/dining table.

"A well-placed island or peninsular can define the separate spaces," adds Herringbone Kitchens' William Durrant. 

3. Get your design and trades lined up in advance

blue and white kitchen extension with large rooflight

A large roof lantern sits stop this modern country style extension's dining table.  (Image credit: Simon Maxwell)

"You can never be too early to start discussions and we are often speaking with our clients a year ahead of project completion," Al Bruce. "Remember, plumbing and electrics can be positioned to compliment appliance placement, by planning ahead you won’t have to sacrifice the layout of your new kitchen."

Don't forget plugs for floor lamps, chargers, music players that are commonly in a dining room that can often be sidelined and forgotten beside a new kitchen.  

"Try to not change your mind too much. Changing your mind will delay things, for example, adding or changing plug sockets are not always quick jobs. However, it is also the right time to do it if you don’t like something," says William Durrant. "Speak your mind and have a close relationship with your builders, pop in often and try to enjoy the process together."

4. Bring in natural light from above or the side

large kitchen diner extension with oak frame vaulted ceiling

Glazed gable and roof lights are celebrated in this vaulted ceiling extension(Image credit: Olive & Barr)

Take inspiration from dining room and kitchen conservatory extensions and bring natural light in from wherever you can. 

Giant roof lanterns on flat roof extensions, stylish corner windows and, of course sliding patio doors are all firm favourite for new additions. 

"Although harnessing natural light has always been a key consideration within interior and kitchen design, we are noticing that our customers are now making it a priority, especially when extending the footprint of their kitchen," says Olive & Barr's Al Bruce. 

"Large atrium-style roof windows are a popular choice and allow light to flood into the room, positioning the island or dining table below anchors the design and creates a show-stopping look."

5. Spend on things you can't change, and mix in budget items

oak frame kitchen diner with pendant lighting

Budget items (like the movable island and bar stools) have been paired with a quality kitchen from DeVOL in this home.  (Image credit: Jeremy Phillips)

At the beginning of your project, its a good idea to find out how much does an extension cost in your area and for the quality you want. From there, you can budget for essentials like the kitchen, flooring, and lighting, before considering finishing touches. 

"It is normal for builders’ quotes to vary massively, so don't go with the first quote you get. It will depend on how busy they are, what else they have in your area, how much they want the job and how well they think you’ll work together. Remember - cheap is not always best!" says Herringbone Kitchens' William Durrant. "It is important to have a good relationship with your builders and strong communication, this will help during the issues that will inevitably arise."

Don't forget that this style of extension is a flexible and social space — don't only spend on your kitchen and forgo the dining element. 

6. Use banquette seating for an integrated diner

light blue bench seating with wooden dining table in white extension

Banquette bench seating means this dining table can be positioned closer to the wall — making a clear throughway from the hallway (right) to the outside.  (Image credit: Pete Helme)

"Often the ideal when undertaking this kind of extension is to include an island and some form of dining area," explains Adrian Bergman from Plain English. "In many cases, this is achievable with clever design but if it is feeling tight don’t be tempted to cram everything in. If you are tight for space a good way to keep the dining area compact is to incorporate a built-in bench seat."

Banquette seating can also be used for a flexible work space for adults or children doing their homework. 

7. Make the dining table the place to be

farmhouse country style kitchen with dining table and window

The dining table is the star of the show in this farmhouse country kitchen.  (Image credit: Plain English)

While the kitchen is usually celebrated in modern house extension ideas, the dining table needs to be kept centre-stage and focused during the design of the layout. 

The kitchen is a sociable area, but the dining table is important for family evenings detailing the day's events, hosting guests for dinner, and during special occasions like Christmas and birthdays. Lighting ideas for dining rooms are equally important as kitchen lighting, but have different requirements. Be sure to include good layering to adjust to the right mood, while still being able to see the table and food clearly. 

"There’s no right or wrong as it’ 's completely dependent on the type of property and the scale of the extension," adds Plain English's Adrian Bergman. "Explore various ideas and scrutinise each design until you find what works for you.:

8. Coordinate kitchen and dining room schemes

white and yellow kitchen with large wooden dining table

Clever wall lights have been positioned above the dining and seating area in this extension so the lighting can adapt throughout the day.  (Image credit: Herringbone Kitchens)

"Don't let colour be the last thing you think about. Using complimentary colours or materials to link living spaces together will help the design to flow," advises William Durrant. 

"People are getting braver with their choice of colour," he adds. "Brighter combinations of colour in the whole kitchen, on the island, on the main run of cabinet, on the dining table legs or in the utility are being used more and more. Not only does it add personality and style but it also sets the mood of the space."

9. Choose cupboards that hide away mess

green larder and pantry unit in kitchen

Large larder and pantry kitchen units like this are ideal for hiding away clutter.  (Image credit: LochAnna Kitchens)

Open plan is ideal for creating a social environment where those cooking still feel involved in conversation, but try to organise the design so no one has to stare at dirty dishes once the food has been served. 

Corner units with bifold doors keeping it neat, tidy and doesn’t obstruct the work flow of the kitchen when it’s in use, says William Durrant. "They also avoid clutter spilling into the kitchen worktops and we love how they are almost secret doors into Narnia." 

Other ideas might include a separate 'prep' area that can store used appliances and cutting boards.

How much does a kitchen/diner extension cost? 

While costs for any kind of extension are rather difficult to pin down given the current climate (namely materials and labour shortages), basic estimates sit at around £1,500/m2 but could increase up to £2,250/m2 (or higher). 

These costs can be altered by the amount of DIY you are willing to be involved with, construction material, the complexity level of architectural design, and whether the project needs planning permission. 

How much value do kitchen diner extensions add? 

Extending a house will generally increase a home's value, but a single storey extension for a new kitchen and dining space is not be best way to increase the value of a home. 

Loft conversions and double-storey extensions (which add either a bedroom or a bathroom) will offer more return on investment, according to Checkatrade

Amy Reeves

Assistant Editor Amy began working for Homebuilding & Renovating in 2018. She has an interest in sustainable building methods and always has her eye on the latest design ideas. Amy has interviewed countless self builders, renovators and extenders about their experiences for Homebuilding & Renovating magazine. She is currently renovating a mid-century home, together with her partner, on a DIY basis, and has recently fitted her own kitchen.