Garden Office: Build Your Own

Building a home office in your garden is a great way to create a quiet, separate space to work, away from the distractions of home. It can also add value to your property.

There are two main routes to building a garden office: off-the-shelf garden buildings or a bespoke design from a specialist company or architect.

Kit garden offices are a popular choice as they tend to be affordable, easy to install and come in a variety of styles, materials and finishes. They can also be decked out internally to suit your tastes and requirements.

If you want something perfectly tailored to your property and lifestyle, a bespoke garden office allows you to cherry-pick the size, layout and how it sits within the context of your home and garden. You'll also have more freedom over everything from external cladding materials to doors, windows, insulation type, flooring and more.

Whether you go for a prefab or bespoke design, there are some key considerations to keep in mind. Firstly, ensure you follow certain conditions to avoid having to apply for planning permission. You'll also need to think about the type of foundation your garden office will need and whether you want to include electricity, WiFi, plumbing and heating.

Planning permission and regulations

Garden offices are considered to be permitted developments, so they can be built without planning permission. However, you need to ensure that certain conditions are met. These conditions vary slightly depending on the source but include:

• The garden office must be a single-storey structure.
• Roof eaves should not be higher than 2.5 metres. For a dual-pitched roof, the maximum height is 4 metres, and for any other roof type, the maximum is 3 metres.
• Any balconies, verandas, or raised patios cannot exceed 30 cm in height.
• The building must be at least two metres from any boundary walls.
• The building must not cover more than half the area of land around the original house.
• The building cannot be used as separate living accommodation.

If your garden office complies with the above, you won't need to apply for planning permission, and you can have a garden building with an internal size of up to 30 square metres. Anything bigger than this will need to go through building regulations.

If you live in a listed building, an Area of Outstanding Natural Beauty, or a Conservation Area, you will need to apply for planning permission regardless of the design of your garden office. If you are in any doubt, it is always best to check with your local planning office. It is also polite to inform your neighbours of your plans.

If your garden office is going to be used as a primary workplace for a business, you will need to consult your local planning authority. Holding meetings, having staff come and go, and using the space for frequent activities that may cause a disturbance (for example, through noise or parking issues) will impact whether or not your garden office will receive planning consent.

Planning permission rules are stricter for properties on designated land, such as national parks and Areas of Outstanding Natural Beauty. In these cases, if your garden room is going to be placed within 20 metres of your house, the maximum area covered is restricted to 10 square metres. On designated land, you will also need planning permission for any garden building that is placed at the side of your property.

Budgeting for your build

Determine the Size and Type of Garden Office

The cost of your garden office will depend on the size and type of structure you want to build. The price can range from £3,000 to £35,000 or more, depending on whether you opt for a pre-made kit or a bespoke design. Consider the amount of space you need and whether you want a simple garden room or a fully functional home office.

Materials and Labour

The cost of materials and labour can vary significantly. If you plan to build it yourself, you may only need to budget for materials. However, if you hire professionals, their rates will depend on their skill level and the complexity of the project. Don't forget to include the cost of any additional features, such as insulation, plumbing, or electrical work.

Foundations and Groundworks

The type of foundation and groundworks required will depend on the size and weight of your garden office. Concrete slab foundations are common, but if your garden is sloping, you may need concrete pile foundations. Ensure you budget for any ground levelling or landscaping work needed to prepare the site.

Electrical and Data Connections

Budget for electrical work to connect your garden office to the main power supply. This may involve running armoured cables underground or along a fence. If you require data connections, consider running ethernet cables alongside the power cables. Discuss your requirements with a qualified electrician to get an accurate quote.

Additional Features

Do you want plumbing for a sink or toilet? Are you planning to install heating or air conditioning? These additional features will add to your budget, so be sure to get quotes and plan accordingly.

Permits and Planning

Don't forget to include any costs associated with permits and planning applications. While garden offices are often considered permitted developments, there may be specific regulations or restrictions in your area. Consult with your local planning office and allow for any necessary costs in your budget.

Contingency Fund

It is always a good idea to have a contingency fund to cover any unexpected costs that may arise during the build. Allow for at least 10% of your total budget as a contingency to give you peace of mind and help you manage any unforeseen expenses.

Creating a detailed plan and obtaining quotes from suppliers and tradespeople will help you refine your budget and ensure you have a clear understanding of the costs involved. Remember to keep track of your expenses throughout the project to stay within your budget.

Foundations and groundworks

The groundwork for your garden office will depend on its location. You should ensure that it is easily accessible from the main house and in a good line of natural light. You should also assess the general ground conditions, surrounding trees, flood risk, and the possibility of any buried existing services. Avoid placing your garden office close to trees and their roots, as this can cause the surrounding soil to expand and contract, compromising the building's structure.

The type of foundation will depend on the size and weight of your garden office. The most common footing tends to be a concrete slab, providing a level base that can be reinforced with steel. Timber joisted floors are also popular, often set atop ground screws. For tricky sites and anything other than conventional foundations, you'll need a structural engineer.

If your surface isn't flat, you may want to invest in some landscaping. You can use type 1 MOT to provide a tough base to build on. You can then lay out the corner plinths to your required dimensions. Using a spirit level, you can level the slabs. You can then start building the frame, ensuring it is squared off with each corner at a right angle.

Additional Support

You may need to add additional support slabs so that the floor doesn't flex when extra weight is added. This will require further digging and shifting of the MOT. Ensure there is enough space for the boards to be screwed into the frame alongside the other boards. Secure the boards down using screws.

To finish off the base and floor, add another full board and cut the remaining boards to fit using a circular saw. If you have a good square base, everything should line up nicely down the edges.

Insulation

You might want to consider insulating the floor. This can be done retrospectively using cork acoustic and thermal insulation rolls.

The Garden Office Walls

When building the wall frame, start by adding the posts to the corners and measuring the distance in-between. Then, build another frame with timber, measuring the correct length of the building. Add struts in intervals to allow for the insulation to fit snugly between. Nogins should be added a certain distance up from the base timber.

You can then screw the wall frames into the base and the corner posts. To add strength to the structure, insert diagonal supports on the frame.

The Garden Office Roof

For the roof, you can opt for a dual-pitched roof supported by lengthways rafters running from end to end. Another option is a flat roof, which will only require one side of guttering.

Exterior

You can cover the exterior walls with cladding. There are many different types of cladding, and most will provide adequate protection from the elements, so it's down to personal preference and aesthetics. Options include log lap cladding and shiplap cladding.

Interior

When thinking about the interior layout, consider where you want power in the garden office. You can feed cables through the timber frames by drilling holes. You'll need a qualified electrician to install your electrics and sign everything off.

Cost

Professionally installed garden offices of this size will cost on average £15,000 to £20,000 depending on where you live. However, if you build it yourself, it can cost about £4500.

Building the frame

Step 1: Prepare the Ground

Before you begin, ensure your surface is flat and level. If not, you may need to invest in some landscaping. Mark out the dimensions of your office, considering any restrictions due to existing structures. Use a spirit level to ensure the surface is level, and dig out the ground if necessary.

Step 2: Lay the Foundation

Place support slabs at the corners of your marked-out area. For added toughness, use Type 1 MOT (a type of crushed stone) as a base. Ensure the slabs are level by adjusting with a spirit level and digging as needed.

Step 3: Build the Floor Frame

Using C16 timber, screw together a frame that fits over your slabs. Drill pilot holes before inserting screws to prevent the wood from splitting. Space the timber supports at intervals of 610mm, which is half the width of the MDF boards that will be placed on top.

Step 4: Protect the Frame

Wrap the outer frame with plastic sheeting, stapling it in place to protect it from water damage and rotting. Ensure the frame is square by measuring diagonally from corner to corner and adjusting until both diagonal lengths are equal.

Step 5: Add Additional Supports

Place additional slabs and dig out the ground as needed to provide extra support for the floor. Ensure there is sufficient space to screw the MDF boards into the frame.

Step 6: Lay the Flooring

Secure the MDF boards onto the frame using screws. Cut any remaining boards to fit using a circular saw. Ensure the boards extend to the edge of the frame for better water protection.

Step 7: Insulate the Floor (Optional)

Consider insulating the floor to make your garden office more comfortable. This can be done retrospectively with cork or other insulating materials, which will raise the floor slightly.

Step 8: Build the Wall Frames

Construct the wall frames using CLS timber. Measure and cut the timber to fit your desired dimensions, allowing for any windows or doors. Join the corners with posts, and add struts and noggins for support and to accommodate insulation.

Step 9: Build the Door Frame

Measure and cut the timber for your door frame, ensuring it is slightly larger than your door to allow for easy installation. Construct the frame, ensuring it is perfectly square for the door to open and close properly.

Step 10: Add Interior and Exterior Walls

For added strength and insulation, you can attach OSB or ply board to the interior of the wall frames. For the exterior, you can use cladding such as log lap or shiplap. Ensure you seal any gaps with silicone sealant to create a watertight and airtight barrier.

Step 11: Build the Roof

Decide on the style of roof you want—flat, apex, or dual-pitched. Construct a sturdy frame using C16 timber, with rafters running either lengthways or upwards to the apex. Cover the roof with OSB boards, and add a waterproof barrier such as felt or EPDM roofing.

Step 12: Finishings

Add any desired finishing touches, such as guttering, electrics, and interior fittings. Consider adding insulation and plasterboard to the interior for added comfort.

Insulation and interiors

Insulation is an important consideration for your garden office, as it will ensure the space is comfortable to work in all year round. Rockwool, fibreglass, and foil-backed foam are all good options for insulating the walls, floor, and ceiling. If you're on a budget, fibreglass is the most cost-effective option and also helps with soundproofing. However, it can be a challenge to work with as the fibres can get everywhere. Remember to wear a mask when handling fibreglass.

When installing insulation, make sure there is a small air gap in the walls to trap warm air and limit sound movement between layers. You can use long screws at an angle to keep the insulation in place.

For extra thermal efficiency, you can add a vapour barrier. This will keep the humidity out and prevent cold air from blowing in. However, be careful not to create an overly airtight space, as this can lead to condensation and mould issues.

After installing the insulation, you'll want to add plasterboard or drywall. This step can be challenging, especially for the ceiling, so consider hiring a plasterboard lift or getting some extra hands to help. Filling in the gaps and holes and sanding them down will give you a smooth finish.

Finally, you'll want to add some flooring. Laminate flooring is a popular choice as it's easy to install and offers a neat finish.

Interior Design

Now for the fun part—designing the interior of your garden office! Start by thinking about the furniture and how you want to lay it out. An ergonomic desk and chair are essential for a comfortable and efficient workspace. Don't forget storage solutions like filing cabinets and shelves to keep things organised and clutter-free.

Lighting is another key element. Adjustable task lighting can enhance productivity, while a brightly coloured sofa or neon signs can add a touch of personality to the space.

If you're feeling creative, you can even add some unique features like a gaming desk or a garden office log cabin. The possibilities are endless!

Frequently asked questions