What is a garden room extension?

As with many trends that spring up and become popular, the very definition of a garden room extension isn’t an agreed-upon concept. There is a consensus that a garden room extension is a room that is built to the same standards as the house itself and usually involves a lot of glass. However, there are some that would classify it as something always attached to the house, and others who suggest that it’s a separate building in its own right. Also, there is the manner in which the extension can be attached to the house. It could be created by knocking through part of a wall, extending the length of a space, or it could be joined by an external quality door for a stronger separation.

Before we head into the aspects that are true of all garden room extensions let’s better define what these types are:

An extension to house

  • Open to main floorplan. 
  • More like a traditional extension.
  • Usually characterised by lots of glass but you are restricted in the amount you can have by ecological planning limits.
  • The option that makes the garden room most feel like an integral part of the house.

Sunroom/garden room extension

  • Thermal separation with main house via external quality door. 
  • From the exterior looks like part of the house.
  • A new door is built between your house and the garden room to the quality and spec of an exterior door.
  • Characterised by lots of glass which is unlimited as the room is separated from the house by an exterior grade door.
  • Despite being attached to the house can feel separated due to sound proofing, great natural light and the external grade door.

Detached ancillary garden room

  • Shares the quality of build with the house but is entirely separate.
  • Characterised by lots of glass to enable panoramic views into the garden or landscape
  • A different proposition to the other 2 in a lot of ways due to the separation.

Type 1 and 2 share a lot of similarities so in this article we’ll be dealing with those in particular. Type 3, the detached garden room, has some stark differences that make it a different beast altogether to deal with. We’ll side-line the detached garden room for the moment but will return to it in a later article.

Why Are People Interested In Garden Room Extensions?

There’s a lot of interest in garden room extensions at the moment due to a number of factors. Due to recent worldwide events people are looking at ways to improve their home and make better use of the space they have. Also, with the future of travel looking blurry having nice ways to spend a summers’ day or night close to home is attractive. If you’re lucky enough to have a sizable garden it’s a good way to use a part that really doesn’t serve a purpose other than to be added to your list of maintenance activities!

Climate change is affecting the world in a myriad of negative ways. But the evidence is seen that the UK will probably see rising summer temperature in the years to come. Adaptation Scotland ( funded by the Scottish Government ) say climate change has brought us to the point where a Summer as hot as 2018 will occur every 4 or 5 years. If things continue as they are, hot summers like that might occur upto 50% of the time by 2050. Predictions like that lead people to wanting to improve the outdoor aspect of their home, including ways to better enjoy it. A garden room extension is a great way to achieve that goal.

What Are Some Of The Benefits?


A garden room extension can be your getaway literally on your doorstep. After a long day at the office or the home office you can relax and feel the warmth of the evening sun through the copious amount of glass around you. Regardless of choosing an attached or detached garden room, being extruded or apart from the house gives a sense of separation and of being more in the green of your garden.

Unlike a summer house or a conservatory, a garden room extension is very much on par with the build of the house. A sturdy roof and constructed in line with the main abode it feels more like a natural partner to the home.

Build Quality


What your garden room is today does not define its future. Essentially your house will gain a room. It could become a playroom in the future if certain additions are made to family. It could morph into an office if a new role is secured. A garden room extension can grow with its owners.

A garden room should be warm all year round. Insulation and build requirements mean that your new room will be in line with the house regarding temperature. You’ll be able to sit and watch the snowfall in winter and feel the warm summer air waft through the open doors 6 months later. Unfortunately these are not part of our build guarantee!

For All Seasons


A garden room extension with an exterior door separation, or even a curtain, provides a nice added area for privacy if needed in the household. A guest could be entertained in peace while the rest of the house continues without pause.

This extension might be your first chance to properly customise your own house. Would your new garden room benefit from extra storage for the children’s outdoor toys? Or maybe a large built in cupboard for the plastic swimming pool and tents. This extension can be exactly what you need.


What About Planning Permission, Building Warrant and Paperwork? provides a very good breakdown of situations where a formal submission for planning permission may not be needed (permitted development) . If your garden room extension satisfies these requirements you’re probably in the clear and may only require a building warrant.

If these are satisfied by your plan you might not need planning permission:

A garden room extension might not be as hard you think!


The plan is to locate the garden room extensions at the back of the house.


It, and any other development, does not take up half or more of the ‘curtilage’ – this means half or more of the grounds behind your home.

New Development

It will not be used as a separate home to live in.


It’s not higher than 4 metres at the highest point.


No part of the build that’s a metre or less from the boundary is no higher than 2.5 metres


The eaves ( the part where the wall meets the roof ) is no higher than 3 metres

ABC Architecture will help guide you through this stage of the project. The experience we have is extremely useful when trying to carry out such builds in an efficient and speedy manner. We can advise on what permissions you will need and set out a simple yet comprehensive quote covering each step of the process.


1. Initial Meeting

After initial contact and a quick consultation we will arrange a time to visit the location. You’ll meet the designer who will accompany you through your journey and be available for questions and queries throughout. We will talk through your ideas, things you like, what you don’t like and we will offer suggestions and thoughts about these early concepts. 

2. The Drafts

Alongside a discussion of budgets we will come up with some draft sketches to start bringing the project into the physical world. It’s good to bring up budgets at this early stage as it very much informs what’s possible for your project.

3. Feasibility Stage

During the initial phases of the project there will be an in-depth feasibility stage. This is, as it sounds, to check many facets of the plan to ensure it can be carried out in the situation present. Any planning permission requirements will also become highlighted during this time. Early discovery of needs here means we can be one step ahead of potential speedbumps arising in the future.

4. Back and Forth

We will go away and work on some more filled out designs for your examination. The process here is something of a back and forth where we zoom in on a plan that you are happy with and fits within your design brief and budget. When the final plan is decided we can move on the paperwork requirements and we can start to develop a timeframe for the project.

5. Final Drawings

With a plan in hand that both ourselves and you are happy with we will retreat to the technical drawing board for the final touches. Relying on our many years of experience we will produce the detailed construction drawings necessary to leave nothing to chance. These drawings will give the construction team the agreed upon blueprint from which to build our vision. Also, they allow us to have the project fully checked over and receive an official building warrant.

6. Construction

At this stage our work is far from finished. We will be in contact to offer guidance on the upcoming construction phase. The full range of our experience is at your command as we can advise on tender for the project and site administration aspects. Expect us to be there to see your proposals carried through to the fully completed project.

Some things to keep in mind...


Is there good access to where the work will be carried out without going through the house? A gate to the backyard with access would be best.


Think about how you’d like the space heated. It could simply extend your current home heating solution. Or, it could have something separate.


In the northern hemisphere having glazing facing south is the best direction for maximum sunshine. When you get a chance, on a sunny day, maybe go out to a suggested location and see where the sun moves and where trees might block it.

Sliding Screen

If you’re lucky enough to have a large section glazing facing south you might want to consider some sliding screening panels. You can, for example, get louvred screens to diffuse the light and heat on an uncomfortably warm day. This is also worth thinking about if you expect to be using a laptop or computer in the garden room too.


Is your garden going to be a distraction-free paradise or will there be devices and charging points abound? Consider how many mains electricity points will be needed. Might be a good chance to put in some with built in USB charging capability too.


Highly efficient double glazing for any garden room extension is a must. When you have a lot of glass you are inviting more heat to escape. We can best mitigate that with high quality windows and doors.


Bifold doors are hot property at the moment. They give you the most open option. Imagine nearly all your glazing folding to a thin concertina at one end of the space.

Sliding Doors

Sliding doors are a more cost effective option than bifold and still allow a sizeable open space.


Part of the building could be set aside as a shed alternative. If you’d like to get rid of an old garden shed or need some extra room this is something to consider. It would have a separate door and a partition wall to keep it very much apart.


If you love your TV you might need to consider where it currently sits. If your garden room extension isn’t going to be separated by an external grade door be aware that a lot of new light will be streaming into your house. No-one wants sunlight creating glare on their television


If you’re worried about the garden room getting too hot you could consider an overhang that pushes past the glazing. This will stop high summer sun from hitting inside the room but allow low winter sun in when you need it most for its heat and light.

Window Seat

A built in window seat using a wide shelf for the glazing on one side is a lovely touch and gives a perfect location for some private solitude.

What We Can Offer

We hope you’ve found something of interest on this page. If you’ve any questions or comments please contact us here or use the form at the bottom of the page. The team at ABC Architecture are ready to leap into action if you’re looking for a garden extension room or any other architectural needs.

As stated in the process above we will be with you every step of the way. We will be upfront about issues and give you access to the full range of our experience in the field. You’ll get a single point of contact and there will always be a friendly voice to answer your calls. We have an eye for clean lines and detail and will ensure your project is designed and constructed to a high level while maximising your budget to its best potential. Ultimately we want to construct the project you have in mind, we are not here to take over your vision.

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