Top 20 House Extension Ideas to Transform Your Home
Everyone wants more space however it’s really important to consider how an extension can really benefit your home.
Each house is different in it’s own way and the existing layout of the home will have a bearing on what kind of extension would suit it best.
We answered few questions based on our residential experience on past projects.
1. What are some of the most innovative house extension ideas you’ve implemented for clients?
Our Blue House project shows the benefits of a two storey rear extension where a mezzanine space sits above the kitchen / dining space. This allows for double height spaces at ground floor level either side of the mezzanine, using roof lights above to bring light and ventilation. The mezzanine itself has a 3m internal head height so feels like a very spacious and calming space.
2. How do you approach blending the old structure with a new extension to achieve a
cohesive look?
When you try to ‘match’ an existing material this can often go wrong.
It is sometime best to take the existing materials as a reference and use this inspiration for something new. For example our Clay House project in Kentish Town, Camden uses the London stock brick as a starting point but uses natural clay render to pick up on the colour tones.
3. What factors do you consider when deciding between a single-storey vs. multi-storey extension?
There are many points to consider when deciding the scale of an extension. Some may be more practical, such as planning restrictions in the area or cost considerations.
The function of the space will have a factor also, for example a kitchen may benefit from a tall two storey space to allow heat and smells to dissipate in the space.
For our project in Brancaster, North Norfolk for example, it made sense to create a two storey space as this fitted best with the existing form of the house as this was a retrofit project.
That being said, the majority of extensions are single storey, particularly in cities such as London. Rights of light and overlooking will be key considerations.
For example our Fitzwilliam Road project in Clapham has a side extension on an existing party wall which could not be removed so this became a feature of the project with exposed brickwork internally.
It has a glazed pitched extension to minimises overshadowing and maximisesprivacy.
4. Could you explain how natural light influences the design choices for an extension?
As architects we will always look at a project in terms of its aspect and how light will affect the internal space.
For example a south facing extension can bring much needed light and warmth in the cooler months but also potentially overheat in summer. Our Nook House in Denmark Hill, Lambeth, uses particularly deep window reveals to provide shading in summer with its deep window seat. Likewise our material palette is often focused towards light, natural materials which can reflect light into a space.
Natural light has psychological and health benefits. It improves mood and productivity, helps regulate circadian rhythms and creates a sense of spaciousness and connection to the outdoors.
Light transmission from buildings can also play a factor. Our Blue House project also uses a specific type of glass which limits light pollution for the surrounding wildlife.
5. What trends are you currently seeing in extension design, and why do you think they’re popular?
We think that buildings need to be more flexible in the future and homes are increasingly the place where we spend most time.
A home can be a place to eat, sleep, rest, work, work-out and so on and this may well change over time.
The Covid-19 pandemic demonstrated this to us. This doesn’t necessarily mean more open-plan living.
Examples might include home offices which can become guest rooms. Storage which can also become a work space and so on. The key is the flexibility of the space.
Energy efficiency is really important to clients now and has always been embedded in our designs as architects. Moving away from gas and oil to cleaner energy sources becomes fundamental to any medium or large scale residential project nowadays.
Embodied carbon is something we are now able to quantify and can make informed design decisions when deciding to pursue either timber or traditional masonry construction.
6. How do you incorporate sustainable materials or eco-friendly solutions into extension projects?
We factor this in to all of our design decisions. One example of this is the kitchen worktop – there are now many materials which are recycled from other building materials, for example terrazzo or recycled plastic.
Likewise Quartz has received negative press of late for the high silica content which can cause health issues when cutting. This requires us as designers to source the materials which are giving more care to these aspects of design.
Our aim is to reduce plastics in construction so swapping PIR insulation for examples such as mineral wool. This allows for more breathability in the building and can alleviate some issues such as damp internally.
Some other suggestions are roof-mounted solar panels with battery storage for excess energy. Rainwater collection systems for things like flushing toilets or garden irrigation.
Investing in the long term generally means you are getting a higher quality product which will last longer, increase the value of your property and have a lower energy cost in the long run.
7. In your experience, what are the key features that turn a simple extension into a standout architectural element?
Quite often we are working with an existing element so the relationship between these elements has a large bearing on what makes a project unique. So much building work in the UK is done without any meaningful design expertise which results in a very homogeneous and uninspiring built environment generally.
Having an architect involved ensures you are not getting a ‘standard’ solution and will end up with something considered and specific to you.
8. Can you share a case study where a small extension drastically improved a home’s functionality?
Our project Clay House in Kentish Town is a good example where a very small increase in footprint had a large impact on how the home works now and that sometimes, bigger does not mean better.
Previously the rear room was a ground floor bedroom which had damp issues from the terrace above. This was reconfigured to form a new kitchen, dining and living space with a side extension.
This widened the space in a practical sense but also achieved a much greater exposure to the garden and how the property interacts with its context. It was a typical London ground floor flat which has now been made to feel like a unique property and a much more liveable 2-bedroom apartment which has both greater appeal to the wider buyers or rental market and as a place to live for the current owner.
9. How do you balance a homeowner’s aesthetic preferences with practicality and longterm value?
Design decisions can be a continual back and forth, a negotiation between practicality, cost and how this sits in the overall space. Our job is to provide clarity (we hope) to our clients when making these choices so that the aesthetic is coherent but also interesting and even playful.
Our Balmore Street project is a good example of this, where each room has a very unique quality, using different materials and techniques yet with a narrative which works across the house more generally. Some decisions need to be tempered slightly with the need to preserve long term value but at the same time we believe that something unique will always have value.
We do like to create designs that can serve as a canvas for each client to appropriate the space as they see fit in the future.
10. What role does interior design play in ensuring the extension flows seamlessly with existing interiors?
Normally we try to work with what is there already and then derive a palette of materials and colours which works with the existing fabric, the clients’ needs and desires and us as an architecture practice.
We would never design something which we think is jarring against the existing.
At the same time, when dealing with a heritage building for example, it can be useful to think of a contrasting style which will be visually separate and avoid the tendency for ‘copying’ or a pastiche response.
11. Do you have any tips for homeowners hesitant about investing in a large-scale extension project?
Embarking on a large project is daunting of course. Most of us will only ever do this a handful of times in our lifetime. However we have to consider that most of our time, generally speaking, will be spent in our homes over periods which might span generations.
In the long term, you have to consider the value of this and the impact this might have on your health, wellbeing and enjoyment.
The housing market in this country may be something of an unknown but if past performance is any indicator, over the past thirty to forty years house prices have been on an upward curve which should provide some confidence to those embarking on a long term project.
There is always a question in people’s minds – ‘Will employing an architect really add value to my home?’ The estate agent The Modern House did some research into this topic for themselves and their research analysed the sales of over 14,000 London homes over three years, comparing them on a price per square foot basis. The results showed that the architecture and design focused homes sold by The Modern House achieved a 12% higher selling price on average.
12. How can extensions be designed to accommodate changing family needs over time?
Adaptability is a key consideration for this. One solution for example might be to oversize foundations for potential future additions and extensions beyond the shorter term project.
Making a space flexible without too many fitted items may suit a family with changing needs or the need to use a single space for multiple functions. For example a living space may become an entertainment space in the evening but then a child’s play area during the day.
This requires design thinking.
Ground floor bathrooms and washrooms are often a consideration for those wanting to stay in their home as mobility and other needs change. Healthcare is also changing, trying to remove some of the burden from hospitals and surgeries which are often short on space and bringing some of the medical care into the home where people often feel more comfortable.
13. What types of structural challenges often arise, and how do you overcome them?
We consult with our trusted engineers early on in the process so this can be mitigated. We work with engineers to get the best solution and also to see if efficiencies can be made.
Sometimes when dealing with existing buildings there might be unknowns which you can’t predict. On our Blue House project, we were dealing with some very old building fabric which we could only uncover as the project progressed. We worked with the contractors who have experience with historic buildings and worked in a very careful way without rushing the process which could have led to a potentially dangerous situation on site.
14. How can technology—like 3D modeling—enhance the decision-making process for
extensions?
We work between 2D and 3D all the time. 3D allows the clients to visualise what otherwise might be ambiguous to them and to see materials, light and the overall volume of the space.
Otherwise, 3D modelling can now embed lots of data such as U-values and embodied carbon. The software we use has BIM capacity which is a necessity for larger projects (e.g. multiple dwellings).
15. Do you find certain layouts or room types (kitchen/diner, home office) more suited to extensions?
Most Victorian terraces tend to have kitchen and dining spaces to the rear however the layout of this is very flexible and open to so many possibilities. The era of the property and the existing layout has a big factor in determining the eventual possibilities. In some scenarios an extension might not even be the answer when an outbuilding (e.g. home office) may be more appropriate. It also depends on the preference of the client as some people like to cook and entertain facing the garden and have a more cosy and dark living room whereas some would prefer to have their family room linked to the garden.
16. How do you ensure an extension respects the character of conservation areas or historical districts?
We will often work with a design code or relevant planning policy which is local to that area. We have worked in the past to write similar codes so are familiar with the language and the approach of planners.
In some areas we have direct contact with the Conservation Area panel which can make communication much easier. Part of what makes an extension ‘appropriate’ comes through the planning process however we will always start with what we think is possible rather than revert to the status quo. There is always a way to make something creative and yet respectful to its context.
Some of the best heritage projects are where the new is a direct visual contrast to the old yet still complements it.
17. What advice do you have for clients who want to maximize outdoor views and connections to nature?
A visual connection to nature brings well known health and mindfulness benefits, especially in areas where open space is limited in urban areas.
We think it is important to not always assume maximum glazing is always better. The openings should always relate to something, or focus on something in particular. Orientation is important also, in that south facing elevations rarely benefit from completely glazed facades.
We work with a carefully selected group of glazing companies who can provide well made products which give transparency but also energy performance.
18. Could you highlight any innovative glazing or insulation techniques that improve comfort?
There are many products out there which can help with glare, over heating and light transmission. Glass can be supplied with a tint or coating to minimise heat gain or have an electronic system which recognises the environment and add a tint to suit the situation.
Otherwise, some glass can be supplied with embedded photovoltaic cells to generate energy. Likewise, insulation which is derived from natural resources is more likely to ‘breathe’ thereby improving internal air quality and humidity. Sustainable alternatives using natural materials include sheep’s wool, cork, hemp, and cellulose.
19. How do you address clients’ budget concerns while still delivering impactful design solutions?
We have an initial consultation which discusses budget to see if the overall scope is appropriate for the budget.
From this point we work to design something which is totally bespoke and to the clients’ needs during RIBA Stages 2-3.
At the end of Stage 3 we normally consult our trusted contractors to get an estimate of where the project is at cost-wise. We may at this point need to decide which elements may need to stripped back or made more efficient. On the medium to large projects we sometimes engage a cost consultant to manage costings prior to any building contract being agreed. This avoids potentially endless cost over-runs if the client was to manage the project themselves without any contract in place.
20. What’s your ultimate piece of advice for homeowners looking to embark on a transformative extension project?
We aim to provide a service which goes beyond just design. By employing us we believe we are offering knowledge about the building process in general, access to our directory of suppliers, consultants and contractors.
Our advice to homeowners who do not have much experience in construction is to engage a professional early on in the process who can
help guide them in the right direction when the process can appear overwhelming. It is also important to find an architect and a builder which you have a good rapport with, as projects can take a long time and therefore, a collaborative team is really paramount.
We are always interested in working on all project types, large and small or to collaborate.
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