Outbuildings – what are they and what to consider when adding a garden room

9< September


Outbuildings are all the rage with many of us becoming comfortable with spending more time at home, and therefore making the most of the land and space we have. Whether you envisage a place to relax on the weekend with friends, or if you’re thinking of an outbuilding to create a separate garden office and to lighten the load of people and things at home, we can help you decide which type of outbuilding will best suit your needs and budget.


Unlike a costly extension, outbuildings will create more living space but are totally separate to your home and they can’t be used for sleeping in unless you have planning permission to do so – more on this below. Garden rooms, office sheds, huts and greenhouses all fall within the realm of garden outbuildings and while their purpose is usually for sheer enjoyment, the practicality that they offer is unquestionable also. 

We spoke with Ross Goodwin, Managing Director of MyToolShed and Luke Spear, their 2021 Garden Office Ambassador. Spears says ‘An outbuilding to me is somewhere you can isolate from the main house, that is quick to access, without having to drive or take transport. Ideally it is insulated, sound-proofed and has all facilities required, be it a work-out area, an office space or a relaxation spot. They add instant value to you and your family’s quality of life, improving work/life separation and giving everyone a little more breathing room.

You wouldn’t usually think twice about putting up a shed, but there are some things to consider before you purchase or build a garden room yourself. 

  • If adding an outbuilding is part of a bigger garden design project, see our advice.


Most garden outbuildings come under permitted development so will not need planning permission. There are some limitations to consider; for example:

  • Height: Garden outbuildings must be single storey, with a maximum eaves height of 2.5m, a maximum overall height of 4m with a dual pitched roof or 3m for any other roof;
  • Square footage: They must take up no more than half the area of land around the original house;
  • Design: They shouldn’t include verandas, balconies or raised platforms;
  • Dwelling: They must not be used as a home. You will definitely need to apply for planning permission if you want to use yours as a guest house.

Pro tip: Check whether your local council advise that you apply for a lawful development certificate before any work takes place.


This is where to start as your options are endless and ultimately what type of outbuilding you go for depends on what do you need it for – whether you’re building your own or not. Knowing what you need will help you settle on practicalities, such as whether it is for year-round use or for warmer months only – vital to know as you’ll need to decide how sturdily built and well insulated it should be. Additionally, you’ll need to know early on whether you need Wi-Fi, electrics, heating, lighting, extra storage and so on.

If it’s more storage that’s a priority, then a large shed could work, if you want a chill out zone for watching movies, lazy summer (or winter) days then a small and simple garden room will be fine. If you want a studio space or a garden office then you may want a garden room that’s a little more spacious, especially if you know that the kids or the dog are likely to spend some time with you there too. (what)


Garden room and outbuilding costs vary according to their size; whether they are modular or bespoke; the quality of the materials used; the doors and windows specified; the level of insulation required; and the interior and exterior finishes.https://91b34b25a05f091460354e20868f6a38.safeframe.googlesyndication.com/safeframe/1-0-38/html/container.html

For a modular kit, expect to pay anywhere between £2,000 and £30,000. For a completely bespoke building, expect to pay between £800 and £1,600 per square metre.

An all-year room requires heating, ventilation, insulation and electricity. If you go for a bespoke option, this will be arranged for you, but make sure the price includes connection to mains electricity. This requires a Part P registered electrician to relay power through armoured cabling and will cost between £300-500. You should also receive a certificate stating that the work meets current regulations.


If you’re purchasing a garden room then these are your two main options. 

A modular garden room is ordered and supplied in kit form, with some basic elements of customisation available, while a bespoke option will be designed to fit your space and then built on site.

With a modular outbuilding, you know up front exactly what you are getting and for how much. Most companies that sell kits will offer add-ons, such as insulation, door and window options, and storage areas, allowing you to create a somewhat tailored finish. However, you will be fairly limited to what’s on offer in terms of the building’s size and shape – which may not suit an awkward plot.

Many modular buildings are sold for DIY installation, with the pre-assembled walls and roof elements supplied, which saves on costs. However, it’s a job for an experienced DIYer with the right tools – and an extra pair of hands. Bear in mind, too, that the levelling of the site and the construction of the base – whether solid concrete, blocks, paving or timber – is a major part of the job. If installation is beyond you, you could employ a trusted local builder, or ask your supplier if they offer a build service for an additional cost.

With a bespoke design, whether dreamt up by you or an architect, you’ll get a building that exactly meets your needs, design ideas and the size and shape of your plot. It will also allow you to be more adventurous with materials and finishes. However, unless you’re a budding builder, this is a job for a professional, which may make the final cost a little more unpredictable.


Spear actually built his own outdoor garden office room, spending£3,000 in comparison to ‘Pre-made garden offices of this size cost from £12,000 to £20,000 and beyond!’. What’s more, a garden room or office can add 5% to your property value so it’s a sound investment for home.

Spear said ‘Spending £1-3k on your home office will mean it has paid for itself in just a few years with small rented office spaces of similar size (30m2 footprint) costing from £1000 pa, plus rates, to £5k and beyond.’

Ross Goodwin, Managing Director of MyToolShed backs this ‘As seen from the data there are cost-saving benefits to be made from creating your own garden building vs buying a pre-made design.’

‘You get additional space, increased comfort, the knowledge and understanding of how to fix and repair, and even a house price increase that’ll bring a larger real-terms profit vs simply buying an out of the box office outhouse.’

‘However, for those who simply cannot find the time to build their own shed, an affordable pre-made shed still could pay for itself within a few years compared to renting office space. Working from home is the future and an office shed is a perfect option for both profitability and space to differentiate work and play.’ 

Of course, taking on this type of project is really hands on and not for the faint DIY-hearted.