From planning to maintenance, we show you how to create an insulated outdoor room that's suitable for use all year round.  

Garden room constructed from Siberian larch and contemporary panel cladding

Image: Pod Space.

Building a garden room is a relatively inexpensive way to add space – and it can make a glorious architectural statement.

If you would like to gain extra space without the cost of an extension, then a garden room may be the solution you are looking for. From off-the-shelf packages to bespoke builds, they can be designed for a specific use or a flexible space that can be adapted as your needs change. Consider important factors such as insulation, power, internet connection and heating to make your self-contained room feel like part of your home. You may not need planning permission and a good-quality build will add value to your home.

Building a garden room is the ideal option if you don’t have room for the home office, art studio or teenagers’ hangout that would make your life easier. A garden room is often a less expensive solution than an extension, loft conversion, or even moving house. And it’s not just about creating additional floor space. For a home-worker or artist it can offer both physical and mental separation from the house that will allow for more productive, creative thinking.

Read on and take heed of our top tips when building a garden room.

Planning and positioning

A Scandi style garden room in an outdoor space with lots of greenery and pink flowers

Image: Norwegian Log

From home gym to home office, a garden build can be anything you want it to be. The scale and design will be determined by the size of your garden and your budget, but you should also think about its appearance. Do you want a sleek and contemporary glass box or a more traditional style? Made with natural materials that will blend in with your garden, perhaps with a living roof or wall?

To make it feel like a room rather than a big shed it needs to be well-built, insulated and set on good foundations to avoid issues such as damp. These are usually concrete; either a slab or interlocking plinths with steel fixings or on stilts, particularly for sloping sites or where airflow is required underneath.

Building regulations will not normally apply if the floor area of the building is less than 15 square metres and contains no sleeping accommodation. Go to the Planning Portal for additional information.

Carefully consider the positioning of your garden room and whether its proposed location is a shady or sunny spot. A fully glazed, south-facing room may be prone to overheating while a design in a dark corner may be difficult to heat with little natural light. It’s also worth considering its angle in relation to the house. With a fully glazed room, everything inside could be visible, so ensure there is enough storage to keep clutter hidden from view.

‘The key consideration is orientation and whether you are facing the sun,’ says Paul Archer, director at Paul Archer Design. ‘If so, it’s worth integrating some sort of cover. My favourite type is one that feels like part of the architecture and not a later add-on.’

Also bear in mind the access to your garden for materials and machinery. ‘We can deliver garden buildings in relatively small components,’ says Nick Forrester, managing director at Norwegian Log. ‘This means we can take a building along the side of the house, but if that access is not available, every part can be carried through a standard domestic doorway.’

Off-the-peg versus bespoke design

Garden room made from stressed plywood in grey situated at the end of a long, narrow garden

Image: Aston Porter Architects

A tailor-made build, designed by an architect, will be made to your exact requirements. If you are looking to include a kitchen or bathroom and require water and waste services, this is the best route to take as the building company will deal with the utilities and you can stipulate every element from the type of heating to where the wall plugs are positioned.

A more affordable option is a self-assembly model or a modular design and many companies offer complete packages that are designed to be erected under permitted development, often with insulated walls and floors, and a choice of add-ons such as door and window options. If you plan to use your garden room all year round, good heating and insulation is essential, as is a well-lit pathway from the house. 

A bespoke design will be more expensive than an off-the-shelf model. Costs will be also be dictated by the size, quality of materials and the finishes. Basic kit garden rooms start from under £2,000, with more luxurious customisable designs reaching over £30,000. For a bespoke design, expect to pay from around £1,000 per sqm.

Utilities and maintenance

Wooden garden room with red panels and integrated doors

Image: North River Architecture & Planning

If you are managing the project yourself, allow budget for electricity, as well as water and waste, if required. Discuss how you plan to use the space with your electrician so they can install the right number of sockets and light fittings. Underground cables should be deeper than 30 centimetres to prevent them from being damaged while gardening; expect to pay at least £600 for installation. ‘If you want to go off-grid, installing solar panels to the roof of your garden room is a growing trend,’ says Anna Sippel, product marketing man

A cold-water supply requires two separate sets of pipes, one for freshwater and the other to remove waste, laid at least 75 centimetres below ground. Your plumber will identify the best way to remove waste water. If you require a pump station, expect to pay upwards of £400. Talk to your plumber about the possibility of installing a small hot-water heater under a sink as they are not subject to the same regulations as boilers. The installation of a cold-water source and the plumbing-in of a sink will cost upwards of £500. Add at least £2,000 for the installation of a loo; you will need a macerator to reduce waste to a pulp and access to a soil pipe.


How to build a garden room2

Image: Will Pryce

Electricity is a must, even if you’re using your structure only as a casual summerhouse; attractive external lighting can enhance the whole garden. If you want your outdoor room to be usable all year, then aim to provide heating, lighting and plug sockets. Your home’s electricity circuit can be extended to the garden via armoured cables buried in a trench, which can also carry network cabling if you want internet access. Use a qualified electrician to carry out the work.

Heating options

  • Garden buildings should be usable all year, so some form of heating is vital. Extending a gas central heating system isn’t economically viable unless the structure is very close to your main home – you’re better off investing in insulation.
  • The Under Floor Heating Store quotes around £340 for a 200W kit for a 2.5x3m room, including insulation boards and a digital thermostat.
  • An effective renewable solution is an air source heat pump, such as Worcester Bosch’s Greensource, which will cost around £1,500 to £2,000.
  • A wood burner is a good option for bigger rooms; installing one will need to comply with the relevant section of Building Regulations.

Words: Jo Messenger and Emily Brooks


Are you planning to build a garden room? Tweet us any tips you have come across by tweeting us @granddesignsmag or posting a comment on our Facebook page



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