Cost of Building an Outbuilding

Last updated 30th January, 2024

What does constructing an outbuilding cost?

This article covers all the essentials for building an outbuilding. We cover the materials, timeframes, labour fees and much more!

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outbuilding cost

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How Much Does It Cost to Construct an Outbuilding?

An outbuilding is usually defined as a non-habitable building in the grounds of your home. Outbuildings can be designed for a variety of purposes but popular uses include gyms, games rooms, offices, sauna cabins, kennels, studios, pool house, summer houses and simple sheds for extra storage.

The vast majority of outbuildings will fall under Permitted Development rules and should not need planning permission. Using some of the room in your garden to create space for activities that you cannot accommodate in the home is a great idea.

Building an outbuilding is much cheaper than extending the home. If you have plenty of room in the garden and not enough room in the house, then an outbuilding is a great low(er) cost option. Outbuildings are generally more substantial than simple sheds and will usually require power by connecting to an existing electricity source, insulation will be essential too if you plan to use the outbuilding in winter.

Hopefully this article will provide the information required to make an informed choice about outbuildings and their typical costs.

If planning on using your outbuilding as an office or workspace, you will certainly need an electrician to safely connect to the house mains electricity supply. In addition, you may wish to have a seperate phone line and Internet connection.

Larger building companies will be able to integrate all such services and offer an inclusive quote with everything you need, but most local tradesmen will expect you to take care of these additional services yourself, which means doing some DIY or hiring additional contractors. If you would like a quote from a local tradesperson use the “Get a Quote" button and get up to 3 quotes!

Outbuildings vary significantly in their style, type, size and specification. The variables which will greatly impact the actual costs include the type of roof (flat roof much cheaper than pitched), doors (full length bi-folding doors can cost more than the main outbuilding itself!), the services required (electrical, internet/data or water in your new outbuilding), and the choice of all your fixtures and fittings.

Can I do it myself?

A DIY build for basic outbuildings, particularly prefabricated buildings, is quite possible. No specialist tools or equipment are required, though you will definitely need some help, but this can be in the form of a willing mate!

The foundation is probably the most difficult part of the job for a DIY enthusiast, but a concrete foundation is essential for the durability of the building. It may make sense to get someone in to lay concrete foundations, then tackle the rest as a DIY project.

What should I be aware of?

Be very careful digging foundations, rupturing a water/gas main or digging up your electricity cables can be a costly and dangerous problem! But don't be tempted to skimp on the foundations because of this, an outbuilding without a proper concrete base will not be structurally sound and will not last well when exposed to the typical British weather.

Most of the problems with outbuildings are caused by trying to cut costs, usually by cutting corners. Use a proper foundation, get a professional builder to erect the structure, and if a timber building have it treated/painted regularly to avoid damp and rot - anything less will likely just cost you more in the long run!

Another area which can catch some out is the site access requirements. When buying a prefabricated kit always check the sizes to ensure the sections will fit through the gate! Also be aware that builders will charge extra if no easy access and they have to transport all the materials through the house to get to the rear garden.

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Outbuilding Prices

The pricing information contained in this article was gathered from a variety of sources, both online and directly from various builders around the UK. But of course the actual price you pay for an outbuilding will depend on your location, along with the size and type of building.

The average material cost to construct an outbuilding will depend mainly on the size and type of building. The average building specialist will usually charge around £150 to £200 per day to build the outbuilding.

The choice of builder will affect the price too, with small, local builders usually being much cheaper than large national companies. For safety reason, most builders work in a team, with at least 2 members on site at all times. As such, you can expect a daily labour charge of anywhere from £200 to £1000 per day, although this additional cost is usually negated by the speed of completion.

Below are some estimated costs of hiring a specialist to build an outbuilding

Job Description Avg. Cost Duration
Concrete garage on a new concrete foundation £10000 2-3 weeks
Basic sauna or steam cabin in garden £3000 1-2 weeks
Small garden office/studio £9000 2-3 weeks
Prefabricated timber summer house (labour-only) £2500 1-2 weeks

Cost Breakdown

Individual costs to build a small garden office/studio with uPVC windows and pitch roof - Total Cost: £9000






Waste Removal


As long as the outbuilding is not self-contained accommodation, or being used as an extra bedroom, bathroom or kitchen. Then most outbuilding projects will be permissible under Permitted Development rights. But, if you are planning an outbuilding to be an annexe for an elderly relative or a teenager, or using it as holiday accommodation to let, then this will definitely require planning permission. In addition, if the main home is a listed building, then outbuildings are not covered by Permitted Development rights. To be covered under Permitted Development rights, outbuildings must be single storey and less than 3m tall (less than 2.5m if within 2m of a boundary). But it is always best to check directly with your local planning authority in every case.
Small single storey detached outbuildings that have a floor area of less than 15 square metres will not normally require Building Regulations Approval. Even outbuildings up to 30 square metres will not need approval if at least 1 metre from the property boundary. Larger outbuildings will usually require Building Regulations Approval and it is best to submit a Full Plans Submission rather than proceeding with a Building Notice.
Outbuildings should ideally be erected onto a firm level base of concrete, though paving slabs may suffice for smaller buildings. In addition the ground must be completely level.