Kitchen Extension Guide for Architects


Kitchens have evolved greatly in the last hundred years. Larger houses would have had a kitchen in the basement with staff to cook, whilst more modest properties would have a room on the ground floor cut off from the dining or living room. Currently, people prefer to have kitchens that are open to the dining or living rooms for entertaining and spending family time together whilst cooking.

01 Kitchen Extension 1

Benefits of a Kitchen Extension


Increased Living Space

One of the primary benefits of a kitchen extension is the expansion of living space it provides. By extending the kitchen, it is possible to create larger, more versatile areas that accommodate various activities, such as dining, entertaining, and relaxation. This additional space can significantly improve the overall quality of life for residents, allowing for more comfortable and enjoyable living experiences.


Enhanced Functionality

A well-designed kitchen extension can greatly enhance the functionality of a home’s interior layout. With more space to work with, it is possible to reconfigure the kitchen layout to better suit the needs and lifestyle of the occupants. This may involve optimising the arrangement of kitchen appliances, creating dedicated zones for cooking, food preparation, and storage, or incorporating features like kitchen islands or breakfast bars. 


Improved Natural Light and Ventilation

Kitchen extensions offer opportunities to introduce more natural light into the space through the incorporation of features such as skylights, roof lanterns, or floor-to-ceiling windows. These elements not only flood the kitchen with sunlight but also create a seamless connection to the outdoor environment, blurring the boundaries between indoor and outdoor living spaces. Additionally, enhanced ventilation options, such as bi-fold doors or sliding glass panels, can improve air circulation and create a more comfortable environment for cooking and entertaining.


Increased Property Value

From a financial perspective, a thoughtfully designed kitchen extension has the potential to increase the resale value of a property. The additional square footage and enhanced amenities offered by a well-executed extension can make the home more attractive to potential buyers, leading to higher sale prices and quicker turnaround times on the market.

02 Kitchen Extension 2

Design Options for Extending a Kitchen


Extending a kitchen provides many opportunities to enhance the functionality and overall appeal of the space. Below we will explore some of the popular design options for extending a kitchen.


Single Storey Extensions


Rear Extensions

Rear extensions are a common choice for expanding the kitchen space while maintaining a cohesive connection with the rest of the home. By extending the kitchen towards the rear garden or patio area, you can create larger, more open-plan layouts that seamlessly integrate indoor and outdoor living spaces. Rear extensions are ideal for clients seeking to maximise floor space and enhance the flow of natural light into the kitchen.


Side Extensions

Side extensions offer an alternative solution for expanding the kitchen footprint, particularly in properties with limited rear garden space. By extending the kitchen along the side of the house, you can create additional room for dining areas, utility spaces, or storage facilities. Side extensions can be designed to complement the existing architecture of the home, ensuring a balanced blend of old and new elements.


Reconfiguration Options

Extending the ground floor of a property offers the opportunity to reconfigure existing spaces to better suit modern lifestyles. It might be that a dining room can be moved closer to the kitchen or indeed incorporated into an open plan space. The client may feel they need a utility area, or would benefit from a downstairs WC. The extension of a kitchen can provide new layouts that increase the value and functionality of the space.

In addition to reconfiguring the kitchen and dining areas, it is possible to create flexible living spaces that adapt to the changing needs of the homeowners. This may involve incorporating sliding doors, folding partitions, or movable furniture that can be easily reconfigured to accommodate different functions or privacy requirements.


Two Storey Extensions

Two-storey extensions provide the opportunity to not only extend the kitchen on the ground floor but also add additional living space on the upper levels. This versatile design option allows architects to create expansive kitchens with adjoining living areas or bedrooms and bathrooms on the upper floors. Two-storey extensions are ideal for homeowners looking to maximise space and functionality without compromising on architectural integrity or outdoor areas.


Architectural and Other Features

Glass extensions are a contemporary design choice that allows homeowners to enjoy the beauty of their surroundings while enjoying the comforts of indoor living. By incorporating floor-to-ceiling glazing, you can create light-filled, visually stunning kitchen spaces that blur the boundaries between inside and outside. Glass extensions are perfect for properties with picturesque views or garden landscapes, offering a sense of connection to the natural environment.

Roof lanterns and skylights are features that can dramatically enhance the appeal and functionality of a kitchen extension. These elements allow natural light to flood into the space, creating a bright, uplifting atmosphere that enhances the overall ambiance. Roof lanterns and skylights are particularly effective in kitchens with limited wall space or low ceilings, where traditional windows may not be feasible.


Open Plan vs Traditional Kitchen Layouts

Open-plan kitchen layouts have become increasingly popular in modern home design, offering a good flow of space and allowing social interaction among family members and guests. By removing walls and partitions, you can create expansive, multifunctional kitchen areas that accommodate cooking, dining, and entertaining activities. Open-plan layouts are perfect for clients seeking a contemporary, versatile living space that adapts to their lifestyle and preferences.

Traditional kitchen layouts retain separate zones for cooking, dining, and food preparation, providing a more structured and formal arrangement. While less open and fluid than open-plan designs, traditional layouts offer a sense of intimacy and cosiness that appeals to many clients. It is possible to incorporate timeless design elements such as kitchen islands, breakfast bars, and alcoves to create a classic, inviting kitchen space.

03 Kitchen Extension 3

Kitchen Extension Design Considerations


Design Considerations

Many clients will use a kitchen designer/manufacturer to design the intricacies of drawers, doors, appliances and use. However, due to the large scale of a kitchen within a ground floor plan, it can be key to agree a rough kitchen layout with a client before they seek a manufacturer’s advice. This will help better integrate the kitchen with the rest of the ground floor, any windows, rooflights, sewage, water and electrical connections, floor, wall and other finishes, as well as the garden. 

There are no minimum requirements for a kitchen, but if you have never designed one, the Nationally Described Space Standard Draft: Annex B, sets out the minimum kitchen furniture schedule based on the people using a house or flat. This document also contains standard furniture sizes which can help in creating layouts and making sure spaces are big enough, although if the client has specific furniture such as a table or sofa, it is always better to use the latter within a drawing. 

Unless the client is willing to pay for a fully bespoke kitchen built by a specialist joiner, most kitchen manufacturer’s work to a kitchen’s standard dimensions. These will usually be 600mm modules, with possibly larger modules for the sink and hob, from 800mm -1000mm, or 2x600mm modules. Smaller modules of 300mm – 400mm can also be used if there are any remaining spaces smaller than 600mm or for specific uses like wine bottle or spice storage. Any remaining gaps between the kitchen and walls can be filled with joinery matching the kitchen. This can sometimes also be found in corners to prevent doors and handles from hitting the wall or other parts of the kitchen when opened more than 90o.  

When laying out a kitchen design, it is important to primarily integrate the clients needs and uses, as well as the many mechanical restrictions detailed above that may dictate where your cooker, fridge, oven or sink can go if you do not want to complicate existing pipework and connections. 

A common strategy is the kitchen work triangle. This is the idea that most of the work in a kitchen happens between a kitchen hob, sink and fridge. Linking these with an imaginary line creates ‘the work triangle’. The idea being that for an efficient kitchen these elements should be close for efficient use but not so close you have no work surface. In a linear kitchen this is impossible and therefore focus is on the space in between the elements.

Creating a regular triangle for the most efficient kitchen is a somewhat outdated way of looking at kitchen design. People now enjoy entertaining guests in kitchens and have them open onto other spaces and many appliances and items such as dishwashers are now commonplace.

Below we show some of the common kitchen layouts and their dimensions.

First in Architecture Galley Kitchen

Galley Kitchen

First in Architecture Straight Kitchen with Island

Straight Kitchen With Island

First in Architecture L shape kitchen

L-Shape Kitchen Layout

First in Architecture U Shaped Kitchen

U-Shape Kitchen Layout

Mechanical Considerations

Unlike the bathroom, the kitchen waste water pipes will require less space and can be sloped behind joinery. This usually means that kitchens can be positioned further away from the main waste pipe. Another key consideration is electricity. A new kitchen may require more power due to all the high consuming white goods and appliances. This will mean new wiring and maybe even a new consumer unit/fuse box. 

Location of a boiler or gas connection is also important if this is where the new kitchen will be or if the new kitchen will require a gas connection for the cooker.

Other Kitchen Extension Design Ideas


Kitchen Islands

Kitchen islands serve as versatile workstations that centralise cooking, food preparation, and socialising activities. When designing a kitchen extension, you can incorporate a well-placed island to create a focal point that enhances functionality and visual appeal. Islands can be customised to accommodate various features such as sinks, cooktops, or built-in appliances, depending on the needs and preferences of the client.

In addition to providing additional workspace, kitchen islands offer valuable storage opportunities and seating options. It is possible to incorporate drawers, cabinets, or shelves into the island design to maximise storage capacity and organisation. Similarly, the island can be designed with overhangs or extended countertops to accommodate bar stools or seating areas, creating a casual dining space.


Storage Solutions

Efficient storage solutions are essential for keeping the kitchen organised and clutter-free. When extending a kitchen, you can design custom-built cabinets and pantry areas that optimise storage space and accessibility. Floor-to-ceiling cabinetry maximises vertical storage, while pull-out shelves and drawers provide easy access to pots, pans, and kitchen essentials. Pantry areas can be designed with adjustable shelving, slide-out racks, or built-in bins to accommodate a variety of food items and kitchen supplies. Storage solutions offer a great opportunity to get creative and really design options that are bespoke to your client. 

04 Kitchen Extension 4

Designing the Kitchen for the Client


It is important to have in depth discussions with your client to look at all the elements regularly used and make sure they have suitable space for their use and between them.

Some key considerations are: 

  • Does your client use the kitchen a lot?
  • How do they use the kitchen?
  • Does the client want an island even if it’s not a practical solution for the space?
  • Does the client want a space to have breakfast in the kitchen rather than in the dining room / table?
  • How will different elements be used, like the dishwasher, sink, etc?
  • Would the dishwasher be more useful next to the sink or where the dinnerware is stored? 
  • Should the hob and oven be separate elements within the kitchen? 
  • How many appliances, dinnerware, silverware does the client have?Your client may have a lot of appliances or none. 
  • Should the appliances be visible or hidden in a cupboard?
  • How will plug elements work within the design? 
  • Should the bins including recycling be stand alone or integrated into a cupboard?
  • Will the washing machine be integrated into a kitchen or another space like a bathroom or laundry room?
  • Will the fridge/freezer be free staining or integrated?
  • Will the fridge/freeze be a standard dimension, american or two separate smaller fridges?
  • Will the hob require gas?
  • How much worktop space is needed?
  • Is a lot of storage required?
  • How can lighting be integrated?
  • Do the finishes match those of the rest of the house?
05 Kitchen Extension 5

Regulation Requirements for a Kitchen Extension


Below are some key regulation requirements that you should consider when planning and designing kitchen extensions. 


Permitted Development Rights

In many cases, clients can extend their kitchens without the need for planning permission under permitted development rights. However, there are limitations and conditions that must be met, including restrictions on the size, height, and location of the extension. It is important to carefully assess whether the proposed extension complies with permitted development rights or if planning permission is required.


Planning Permission

If the proposed kitchen extension does not fall within permitted development rights or exceeds certain thresholds, homeowners will need to apply for planning permission from the local planning authority.


Building Regulations

There are a number of elements of the Building Regulations that need to be considered when designing a kitchen extension.


Structural Stability 

Kitchen extensions must meet building regulations regarding structural stability to ensure they can withstand the loads and forces placed upon them. You should work with structural engineers to design foundations, walls, and roof structures that meet structural requirements and adhere to relevant British Standards.


Thermal Performance 

Building regulations require kitchen extensions to meet minimum standards for thermal insulation and energy efficiency. You must specify insulation materials, glazing options, and heating systems that achieve the required U-values and contribute to reduced energy consumption and lower heating bills.



Adequate ventilation is essential for maintaining indoor air quality and preventing issues such as condensation, dampness, and mould growth. Ensure you incorporate appropriate ventilation strategies, such as mechanical extract fans, trickle vents, or passive ventilation systems, to ensure sufficient airflow within the kitchen extension.


Fire Safety 

Kitchen extensions must comply with building regulations related to fire safety, including the provision of fire-resistant materials, escape routes, and smoke detection and alarm systems. Be sure to specify fire-rated doors, walls, and windows as necessary to minimise the spread of fire and protect occupants in the event of an emergency.



Building Regulations also address accessibility considerations, however unfortunately these are predominantly optional for house extensions. We would always try to ensure we can provide suitable accessibility features such as increased door widths, manoeuvring space and accessible kitchen fittings. This allows not only for future proofing for the existing occupants, but also provides optionality for future occupants of the home.


Listed Buildings and Conservation Areas

If the property is listed or located within a conservation area, additional regulations and requirements may apply to kitchen extensions. Be sure to conduct heritage impact assessments to assess the potential impact of the proposed extension on the character and significance of the heritage asset. This may involve consulting with conservation officers and heritage experts to develop sensitive design solutions that respect the historic fabric of the building.

In conservation areas, homeowners may need to obtain conservation area consent in addition to planning permission for kitchen extensions. Architects should liaise with the local planning authority and conservation officers to ensure that the proposed extension complies with conservation area policies and guidelines, preserving the architectural integrity and character of the surrounding area.

You might be interested in

We have loads of other incredible architecture content. Be sure to check it out.

Building Regulations for House Extensions FI
Permitted Development Rights for House Extensions FI
Planning Permission for House Extensions FI


Written by Emma Walshaw, Architectural Technologist and founder of First In Architecture and Detail Library. Emma has written a number of books about construction and architectural detailing.

Other recent posts…

Average Male and Female Dimensions and Heights

Average Male and Female Dimensions and Heights

Introduction   Updated July 2024 The average dimensions of the human body are essential in architectural design as they help to ensure comfort and enhance the user experience. These physical measurements, known as anthropometric data, are used by architects and...

17 Best Websites For Architecture Inspiration

17 Best Websites For Architecture Inspiration

Introduction   This post is all about the best websites for architecture inspiration. With so many architectural inspiration websites online, we know how difficult and time-consuming it can be to find the best ones. This is why we put together a list of the best...

Space Planning Basics

Space Planning Basics

Introduction   Space planning is a complex process with many factors to consider. The principles of space planning involve satisfying a defined criteria on a priority basis – as a result, space planning is frequently about compromise. That being said, there is...


Submit a Comment

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.