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Garden Room Extension

Garden room extensions: the ultimate homeowner guide


By Heather · 29 Mar '22  · 

8 min read


Sometimes it can be hard to carve out some personal space in our homes. Whether this is because of noisy children bursting into your home office, or you’re struggling to find the space to stretch those limbs during a yoga session. In cases like these, a garden room might just be the solution.

But how exactly do you bring garden rooms to life?

In this article, our design experts will be sharing their top tips for bringing your garden room to life. Whether you want to create a home gym, office, art studio, or playroom, there’s something for everyone inside our comprehensive guide, including…

What is a garden room extension?

A garden room is a space detached from your property. This freestanding structure can either be built from scratch or converted from an unwanted detached garage. As with most home improvement projects, garden room extensions come in a range of shapes and sizes. For those homeowners on a budget, you could opt for pre-fab models. Likewise, if you have the cash to spare, a garden room could go on to become its own annexe and provide a private residence for an elderly relative or Airbnb guest.

Benefits of a garden room extension

With lots of privacy and a high level of versatility, there’s plenty of love about a garden room extension. However, don’t just take our word for it. Here are some of the top benefits of adding a garden room to your property.

Easy to plan

Unlike wraparound extensions or loft conversions, the structural work required for a garden room is relatively simple. This not only helps keep down costs, but it can also help construction move along smoothly too. What’s more, if you already have a detached garage at hand, which you’re able to convert, the main structural work will already be in place.

Usually, no planning permission is required

If you live in an area known for being strict on planning, then good news! Garden rooms can come under your permitted development rights. This means, while you will need some form of documentation (such as a lawful development certificate), you won’t need to undergo a full planning application. This is beneficial because traditional planning applications undergo a much more subjective assessment process, whereas permitted development projects simply need to tick the right design boxes.

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Extra space

The most obvious benefit is how much extra space you’ll enjoy. Garden rooms come in all different sizes, so the more garden you have to spare, the bigger your garden room can be. Of course, you will need to bear in mind planning restrictions when it comes to larger garden rooms. Especially big garden rooms may need a full planning application - but don’t let this put you off. With an experienced designer by your side, securing approval can be a breeze!

More affordable

Because you won’t have to renovate any existing areas alongside your build, and because you won’t need to move out of the property at this time, garden room extensions tend to be more affordable than other extension types. To keep costs down further, you may even choose to do down the pre-fabrication route, which can have a big impact on costs (though will limit your design options).

Less disruptive than other house extensions

While other extensions will involve builders coming in and out of your house, potentially cutting off vital areas of your home (such as the kitchen), a garden room build can be self-contained in your garden. This will keep the distribution to the rest of the house to a minimum and can mean you avoid needing to rent while it's brought to life. And once the garden room is complete, this self-contained area will be the perfect place to contain any disruptive activities - drum practice, anyone?

A multipurpose room with lots of versatility

Garden rooms are the heroes of versatility and are essentially a blank slate for you to play with. If you don’t believe us, here are just some garden room extension ideas you could explore...

  • Gym
  • Office
  • Music room
  • Playroom
  • Art studio
  • Guest room
  • Garden kitchen
  • Summer dining space
  • Pool house

Alternatives to garden rooms

While garden rooms are fantastic, it’s not the only home extension on the market. If you lack the garden space required or simply want to explore your options, you might want to consider these alternatives.

Get free quotes for different extensions here

Building a conservatory

Conservatories can be just as cost-effective as a garden room and are typically added to the rear of a property. This allows them to extend key living spaces, such as your kitchen or dining room. If you would rather increase the square footage of a communal area, rather than have something detached, this could be the option for you.

Conservatory pros

  • Can be as cost-effective as garden rooms
  • Can be used to expand communal areas
  • They bring in lots of natural light into your property
  • Creates panoramic views of your green space
  • Included under permitted development rights

Conservatory cons

  • Dated uPVC conservatories can be detrimental to the value of your home
  • Cheap glazing can result in a greenhouse effect (too cold in winter and too hot in summer)
  • The amount of glazing means they’re not suited to housing major appliances
  • When used to extend a kitchen, they can result in high levels of condensation

Conservatory kitchen extension from 2019 - the interior

Loft conversion

If you’ve got some loft space going spare, a new conversion could be a fantastic alternative to a garden room, especially if you wanted to add a new bedroom. While ground floor bedrooms are more accessible, you’ll find top floor suites bring in more added home value. And much like a garden room, by adding a whole new storey of space, you give yourself a blank canvas to work with.

Loft conversion pros

  • Can have a more positive effect on the value of your house
  • Qualifies for permitted development rights
  • Creates a flexible new storey of space
  • Can be used to increase insulation in your roof
  • Balconies can be used to create extra outdoor space
  • Doesn’t require garden space to be sacrificed

Loft conversion cons

  • Require suitable loft space to be present
  • Typically more expensive than garden rooms and conservatories
  • Not suitable for home gyms unless the floor is reinforced
  • Construction can cause disruption and be lengthy

Home office - garage conversion

Garage conversion

Garage conversions and garden rooms can be one of the same if you’re extending a detached building. However, even if your garage is attached to your property, you can still use it to create a slick new extension. This is another cost-effective project, as the preexisting structure will help keep costs down and limit the time needed during construction. You can choose to keep your garage conversion as a separate space, turning it either into an office, gym, bedroom, or playroom, or connect it to the living room/kitchen to create one large open-plan layout.

Garage conversion pros

  • A very cost-effective way to extend your home
  • Can be used as a self-contained or open-plan space
  • Included in your permitted development rights
  • Doesn’t require garden space to be lost

Garage conversion cons

  • You will lose car storage space
  • If parking is at a premium in your area, losing a garage can damage the value of your home
  • Some councils will prevent garage conversions if they’re worried about local parking
  • Interior renovation might be needed if you want it to blend into an existing area

Garden room extension costs

If you’re building a garden room from scratch, it’s likely you’ll be looking at the following costs during construction.

Basic build, using a one-man contractor: £1500/m2

Standard, high-quality build: medium scale contractor: £1650/m2

Premium quality build, large scale building contractor: £1800/m2

Get a quick quote for your garden room extension here.

Of course, costs will vary wildly, depending on…

  • Your location
  • Size and complexity of your project
  • Type of contractor used
  • Quality of materials used
  • Prep work required

Learn more: a breakdown of garden room extension costs.

How much value does a garden room bring to my home?

Depending on the project, a garden room extension could add 10-20% to your home’s value.

However, it’s worth remembering that markets fluctuate and so these figures are liable to change. You’ll also find value will be determined heavily by the kind of space you’ve created. Bedrooms tend to contribute the most, but luxurious home offices have also been pushing house prices up. Even your interior design choices can have an impact.

If you’re extending with added value in mind, make sure you discuss your project with a local estate agent. You’ll want to understand local ceiling prices and ensure that your home isn’t already worth the most it can be on the market.

Do I need planning permission to build a garden room extension?

Do you need planning permission? Not necessarily.

Garden rooms can fall under your permitted development rights, which means you won’t require a full planning application, provided your project complies with the outbuilding design guidelines. These are…

  • Outbuildings and garages to be single storey with maximum eaves height of 2.5 metres and maximum overall height of four metres with a dual pitched roof or three metres for any other roof.
  • Maximum height of 2.5 metres in the case of a building, enclosure or container within two metres of a boundary of the curtilage of the dwellinghouse.
  • No verandas, balconies or raised platforms (a platform must not exceed 0.3 metres in height)
  • No more than half the area of land around the "original house"* would be covered by additions or other buildings.
  • In National Parks, the Broads, Areas of Outstanding Natural Beauty and World Heritage Sites the maximum area to be covered by buildings, enclosures, containers and pools more than 20 metres from the house to be limited to 10 square metres.

Discover your garden room planning options with a free consultation

It’s worth noting the rules concerning permitted development are quite technical, so we always recommend working with an experienced designer. It’s also hugely important that you apply for a lawful development certificate, as you’ll need to prove your build was legal at the time of construction - especially if you plan on selling in the future.

Bedrooms and annexes

One very important thing to consider is the difference between a garden room and an annexe. If you intend to have some live inside your extension - meaning it includes a bedroom - then you’ll beholden to different planning rules and will likely need a full planning application.

A successful garden room in the heart of London

A garden room in London, completed in 2015 with bifold doors

A garden room interior, based in London and completed in 2015

This garden room was added to the garden of a ground floor flat in London. We envisioned it to be a self-contained living space, where the family’s elderly relative could find some privacy in the hustle of the capital. The room also has the potential to go on the rental market, should the family wish. Key features include open plan living and large bi-fold doors, which open out on the garden.

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