Essential Factors in Your Garden Office Cost

The most significant factor in your costs will be the size of the office. Typical one-person buildings are around 2.4 by 2.4 metres square and need electrical sockets, lighting, insulating doors and quality glazing.

Small garden offices can range from £5,000 to £20,000, with more significant constructions starting at about £12,000. Here we’ll explore the different customisation options and which elements will have the most significant impact on the budget.

A basic build will cost around £6,000, but you need to ensure your quote includes foundations if required – with most brick garden offices having a concrete slab underneath.

Larger timber or clad outbuildings will also need a foundation. Most contractors will request a site visit to give professional advice about what site preparation work is required.

The material you choose will also be a key cost driver. There are thousands of options, from rustic log cabins to sleek glazed offices or brick-built permanent structures. Here we’ll run through some of the standard cladding finishes:

  • Cedar Cladding is one of the most popular materials, with a warm red-brown colour and natural durability against the elements. Cedar generally lasts for over 25 years but will need regular repainting or staining to keep it in good condition.
  • Thermowood Cladding is made from treated pine and is highly durable. This type of heat-treated softwood can last for around 30 years and ages to a cool silver grey. You’ll often find Thermowood cladding on modular garden offices, which are pre-built off-site and then delivered for assembly.
  • Painted Cladding comes in any number of colours and shades; exterior-grade wooden timber cladding can often be painted to match your design choices.
  • Composite Garden Offices usually come in either cement fibreboard or composite wood. Fibreboards are a straightforward option since they are pre-coloured during production and don’t need repainting. Composite wood is a mixture of natural wood fibres and resins, so it is tough and stable and usually cost-effective. You can choose surfaces made to look like wood grains with special concealed fixings for a contemporary finish.
  • Metal Cladding such as colour coated steel is a no-maintenance home office choice, with powder-coated aluminium another option. These materials are usually mixed with timber cladding, with the metal matching the doors and window frames.
  • Render Finishes can be applied to the whole of the garden office construction or just to parts. Renders are usually made from acrylic or silicone silicate and are resistant to staining or cracking.
  • Slate or Brick Cladding is often used with timber garden office frames, combining textures and materials to create a sturdy, weatherproof office.

The best material for your garden office will depend on the size you need the construction to be, your design preference, and your budget.

Reasonably sized garden offices with cedar cladding, interior plastering and floor to ceiling glazing can cost from £13,000 to £20,000, with bespoke finishes always driving up the total price.

Insulation also has a bearing – and is essential for garden offices that you expect to use year-round. Good quality insulation is more expensive but will ensure the space is usable throughout the year and costs much less to heat.

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Other Budget Considerations in Building a Garden Office

With so many garden office types, it’s difficult to give accurate averages – you might opt for a brick-built construction, a prefab kit or a custom timber build, all of which are different types of project.

However, whatever materials and size you opt for, you need to be aware of all the underlying costs. If any of these are not itemised in your quote, they will need to be budgeted separately.

Examples include:

  • Plumber Callout costs to fit a WC, bathroom or outside tap fitting costs.
  • Glazing – double or triple glazing is the most expensive but the most functional.
  • Doors, including a Locksmith Callout to fit security locks and window catches to protect your work equipment.
  • Electrics, such as lighting, phone connections and plug sockets, requiring an Electrician Callout.
  • Roofing and internal decorating, including plasterboard, flooring and painting.

Once you’re happy with your garden office design choice, it’s also wise to consider the surrounding spaces and what amenities you will need. That might include installing plumbing and drainage or a shower room.

Other costs include a pathway from the main property to your garden office and the costs of laying new turf or landscaping the surrounding area when the construction is complete.

Modular garden offices, delivered as a pre-made set of panels, will usually have cables for power, heat and lighting already included in the structure – and you will only need to pay for a professional to connect them to the mains supply.

However, if not, you might need to have your electrical connection created with a trench dug from the house to the garden office and then filled to secure the cabling.

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Breaking Down a Quote for Your Garden Office Cost

As well as a vast range of design options, there are lots of different suppliers of garden offices. The services included in your quote will depend on whom you are working with – for example:

  • A garden office supplier may include only the panels and erection in a modular garden office – or the price might be inclusive of fitting, power connections and internal decoration.
  • Bespoke garden office suppliers will amend their pricing depending on precisely what you’d like – and if you change your mind about something, this will usually be reflected in the cost.
  • Contractors will tend to offer a full-service, from sourcing materials, installations, and outsourcing any specialist work through subcontractors – their fees will include an element of project management to organise this for you.

The best way to make sure you understand your garden office quotations is to ask for a breakdown showing what is included. You might need to budget for separate costs such as laying foundations or clearing the site – but as long as you know whether they are included, you can control the overall costs.

Many garden office suppliers also provide price lists for ‘added extras’, which you might select and are usually cheaper to install simultaneously during the build than to buy from a separate supplier later on.

Is a Garden Office a Good Investment?

Given that your garden office cost even for a smaller, more basic model will be several thousand pounds, it’s essential to think about how much you have to invest and what return you will get from that investment.

Garden offices and other outbuildings are becoming extremely popular and have diverse uses if you decide not to work from home or your circumstances change.

Fully insulated outbuildings with mains power can be used as sleeping accommodation, home gyms, or extra living spaces, so they are a great way to expand your property’s size without needing to move.

The good news is that a typical garden office adds at least 5% to the value of your home, often adding around £35,000 to the asking price – and the more significant and more premium the space, the more it will add to your property’s saleable value.

However, it’s vital to balance out the amount of outdoor space against your garden office’s size. If you have a large garden and have plenty of spare room that isn’t being used, or can fit a smaller garden office at the bottom of the garden or in a quiet corner, it can be an excellent use of space.

Cramming an extensive garden office into a small outdoor area may have the opposite effect, especially if it removes most of the garden area or doesn’t leave any grass or outdoor seating capacity.

Properties in higher-value areas such as London will typically see the most considerable uptick in their home’s value, with working space at a premium.

Reasonably sized garden offices with cedar cladding, interior plastering and floor to ceiling glazing can cost from £13,000 to £20,000, with bespoke finishes always driving up the total price.

FAQs - Building a Garden Office

Let’s explore some of the most popular questions about the costs and practicalities of building a garden office in your home!

Do I Need a Foundation for a Garden Office?

Most outbuildings of any material will need a stable, level foundation to sit on – and a garden office is no exception. Foundations are essential since they ensure the construction cannot move or slip.

No reputable contractor would consider building a permanent structure on soil since this could quickly erode and mean your garden office is unsafe and requires demolition.

As with the garden office, there are lots of ways to construct foundations, so the best method will depend on the weight and size of your garden office, the materials it is built from, and your budget.

Packages such as modular garden offices may not include foundations, or suppliers may advise what sort of foundation is required for the erection to occur. Most garden offices sit on a concrete slab foundation, which is the simplest and most cost-effective option.

If you are replacing an old shed or outbuilding with a garden office, you might not need a foundation. However, if this is cracked or damaged or doesn’t fit the size of the office, it may need to be removed, and a new foundation poured. For more information, see our page on brick shed costs.

Is Planning Permission Required for a Garden Office?

It depends! Most garden offices aren’t used as sleeping accommodation and won’t have a kitchen or bathroom given that they are so close to the main house. In that case, the construction will often fall into Permitted Development categories and not require formal approval.

Homes in conservation areas or classed as a Listed Building may need additional permissions.

The general rules where a garden office won’t need planning approval are:

  • The building is one storey, and the eaves are no taller than 2.5 metres.
  • The height doesn’t exceed three or four metres, depending on the type of rood.
  • There are at least two metres between the office and the nearest boundary, or the office is under 2.5 metres tall if within that distance.
  • The building doesn’t have balconies or raised platforms over 30 cm tall.
  • The construction takes up less than 50% of the garden space (this relates to the area initially part of the property, so existing extensions need to be considered).
  • Remember that if you need to excavate to construct a foundation or are building a garden office close to a neighbouring property, you may also need a party wall agreement to be allowed to proceed.

How Long Does it Take to Build a Garden Office?

Prefab garden offices or modular build packs come pre-assembled and take a day or two to erect. Contractors may require extra time for electricians and plumbers to attend the site and link up the cables to the main supplies.

Building a garden office on site will usually take around a week or two – if new foundations are required, the contractor will need a day or two to clear the area and prepare the land. Concrete foundations will need to be left to set before they can be built on.

A brick-built garden office will then take around a week to construct, but again it all depends on how large it is, what roofing, insulation and glazing materials you have chosen, and how many tradespeople are required on site.

Can I Build a Garden Office Myself?

You could potentially build your own garden office as a DIY project – but will require professionals to carry out more specialist work. It is also inadvisable to fit a weatherproof roof, pour foundations or build insulated walls if you don’t have trade experience.

What is the Cheapest Material to Build a Garden Office From?

Some of the lowest cost garden offices are prefabricated. However, you might find that a skilled bricklayer could construct a more bespoke outbuilding for a similar price but customised to your preferences.

Timber frames are an affordable option, but again the price can shoot up if you need to install additional cladding, premium roofing or triple glazing.

The best way to assess the costs out there is to request quotations through our form and compare each estimate directly before making any decisions.


Rich Crossley
Having spent 30 years working all over the world for top-tier investment banks, I’ve owned and developed houses all over the world – Europe, the US and Asia. I’m now based back in the UK and involved in the property industry – oh, and I’m a keen DIY enthusiast!
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