The Ultimate Guide to Building a Shed

Constructing a wooden shed isn’t a daunting task, as long as you have a clear plan and the right tools. Whether you’re building from scratch or assembling a garden shed kit, this 7-step guide will help you navigate the process and understand the distinctions between both approaches.  We’ll cover everything you need to know about how to build a shed, starting with creating a solid base, framing the structure, and assembling the walls. You’ll also learn how to build a shed base, how to make a shed base without concrete, and how to build a shed roof. Each stage will be explained simply, so you can confidently take on the project yourself.

Step 1. Laying the foundation for a shed

The foundation is a vital part of your shed, whether you’re building from scratch or assembling a pre-made kit, as it ensures your structure stands strong and level. For shed kits, a base option is often included or recommended in the instructions. On the other hand, custom builds may require more consideration for the type of foundation based on the shed’s design and your local climate.

In either case, there are two main  foundation types to consider: on-grade and frost-proof. An on-grade foundation, often using timber or paving slabs, is quicker and easier, making a great option if you’ve been looking for how to build a shed base without concrete. However, frost-proof foundations, which involve digging below the frost line and setting posts in concrete, offer extra stability for colder climates. Consider these pros and cons based on your climate and shed type. Here’s how to build each type:Clear and level the ground.

• On-Grade Foundation:
  • Clear and level the ground.
  • Lay down a weed membrane, followed by a damp-proof membrane to protect the shed from moisture.
  • Next, install your chosen shed base material, whether it’s concrete, wood or metal. If you’re avoiding concrete, place your paving slabs or pressure-treated timber-frames directly onto the membrane.
  • Check that everything is level using a spirit level.
• Frost-Proof Foundation:
  • Dig holes below the frost line at each corner of where the shed will sit to prevent movement in freezing conditions.
  • Fill the bottom of each hole with gravel for drainage.
  • Insert wooden posts (one at each corner and additional posts for larger sheds as needed) and pour concrete around each to secure them firmly.
  • Use a spirit level to make sure the posts are perfectly aligned and allow the concrete to cure fully before proceeding with shed construction.

Step 2. Building the floor of a shed

Constructing the shed floor is a straightforward process that’s necessary for both pre-made and custom-built sheds. For shed kits, use the pre-cut floor panels included, ensuring you follow the labeled instructions. For custom builds, measure and cut the floor joists yourself, then fit and secure them to create a sturdy base. Here’s a simple four-step process to ensure a solid base for either approach:

• Measure and Cut Timber: Start by measuring and cutting the timber for your floor frame, making sure it’s a perfect fit for your shed’s dimensions. If you’re installing from a kit, use the pre-cut pieces provided.
• Space the Floor Joists: Evenly space the floor joists, typically around 400mm apart, to provide solid support for the floor.
• Secure the Joists: Use galvanised nails or screws to attach the joists to the frame, making sure everything is firmly in place.
• Lay the Floor Panels: Once the frame and joists are secured, lay down your floor panels. Make sure everything is level and secure.

This method is suitable for both timber and on-grade foundations, especially if you’re building a shed base without concrete. Now that the floor is set, you can move on to framing the shed’s walls.

Step 3. Framing shed walls

Framing the shed walls can vary slightly depending on whether you’re using a prefabricated kit or building from scratch. If using a shed kit, walls come pre-cut and labelled, reducing the time spent measuring and cutting. Custom builds require you to measure and cut studs and plates, offering flexibility in design. Here’s how to approach either:

• Cut the Wall Studs and Plates: This step is only necessary for custom builds. Begin by cutting the wall studs, along with the top and bottom plates, to the correct lengths based on your shed’s dimensions. The top and bottom plates are horizontal beams that run along the top and bottom of the wall frame, securing the stud in place and providing stability. For additional support, consider adding noggins short horizontal pieces between studs to reinforce the frame.
• Assemble the Frame: Lay the studs between the plates and secure them, ensuring even spacing, typically 400mm apart, for solid wall support.
• Add Door and Window Frames: Mark out and cut spaces for windows and doors, reinforcing the areas with extra studs or headers for added strength.
• Erect the Walls: Once each section is assembled, lift the walls onto the shed base and secure them, making sure they’re plumb and level.

Step 4. Framing a shed roof

When framing a shed roof, both shed kits and custom builds offer various design choices. Shed kits usually include pre-cut or partially assembled roof trusses and rafters, making it easier to assemble. However, you’ll need to measure, cut and fit each piece yourself for a custom build. Here’s how to frame some common roof types for your custom build:

• Apex Roof:
  • Measure and cut rafters (sloping beams that support the roof) to create two slopes meeting at a peak in the centre.
  • Assemble the trusses (triangular structures that hold the rafters) on the ground, then lift and secure them evenly along the walls for balanced support.
• Pent Roof:
  • Cut rafters for a single slope, where the highest point is at the front of the shed.
  • Secure the rafters from front to back for a sleek, modern look that fits well against fences or walls. 
• Mono-Pitch Roof:
  • Similar to a pent roof, but often used on smaller sheds. Cut the rafters for a slanted design that directs water off one side.
  • Secure the roof frame from one side to the other to ensure stability.
• Reverse Apex Roof:
  • Frame this style by measuring and cutting rafters for two slopes that meet at a central ridge beam spanning the width.
  • Attach trusses along this ridge beam, securing them to the front and back walls.
• Barn Style Roof:
  • A barn roof requires rafters cut to create a series of gentle slopes or curves, rather than a single angle.
  • Begin by framing the walls with evenly spaced rafters that form the desired arc or pitch.
  • Add smaller beams between the rafters for additional support along the curve.

If you plan to skip the concrete when making your shed base, make sure the base is strong enough to support your roof design.

Step 5. Installing shed roofing

Shed roofing can be made from various materials. You could choose a hard roof covering like slates or corrugated sheets, or a simpler felt-only option. Shed kits often include roofing materials cut to size, such as pre-cut felt or shingles. In contrast, custom builds require sourcing and cutting each piece to fit. Follow the guide below to install your chosen roofing type effectively:

Hard Roof Covering (Slates or Corrugated Sheets)

• Install Sarking: Attach the sarking or sheathing boards to the rafters or trusses. Check that they are secure and evenly spaced to form the base for your roof.
• Apply Underlay: Place a layer of underlayment (roofing felt) over the sarking to create a waterproof barrier, protecting against rain and moisture.
• Fit Roof Covering: Choose your top covering, such as slates or sheet roofing (i.e. corrugated sheets). Let the slates overlap properly to prevent water penetration.

Felt-Only Roofing

If you're after a straightforward roofing option, felt-only roofing is a solid choice, providing good waterproofing to keep your shed dry. Just remember, it won’t have quite the durability of a hard roof covering like slates or corrugated sheets.

• Attach Sarking: Secure sarking boards to the rafters or trusses for a stable foundation.
• Lay Roofing Felt: Apply roofing felt over the sarking as the final layer, overlapping edges for a continuous, weatherproof finish.

Step 6. Installing windows and doors in a shed

If you’re assembling a garden shed kit, you’ll find the kit windows and doors pre-framed, which simplifies installation. Otherwise, you’ll need to construct the frames from timber yourself for a custom build. Here’s a quick guide for both options:

• Construct sturdy frames that match the size of the window and door openings.
• Install flashing around the window and door edges to protect against moisture and leaks.
• Carefully position the window or door, checking that it sits level and square.
• Secure them firmly using screws or nails, ensuring they’re properly fastened.
• Seal any gaps around the window or door frames with a high-quality silicone sealant to keep the installation watertight and weatherproof.

This process will help you create a solid and well-protected structure.

Step 7. Shed finishing touches

The finishing touches are just as important as the other steps we’ve highlighted above. They make your shed kit, and custom builds alike, stylish and improve functionality. Kits may include pre-selected cladding, trim, or paint options, while a custom build allows for full customisation. These additions protect against weather and improve storage, accessibility, and ease of use. Here are five essential finishing touches to consider:

• Install cladding to shield your shed from the elements while giving it a professional look.
• Paint or stain the exterior to personalise your shed and protect the wood from weather damage.
• Fit trim and hardware around the windows and doors to create a neat, polished finish.
• Add shelving inside for extra storage, maximising space.
• You may also consider installing a ramp for easy access, especially if you plan to store wheeled equipment or larger items.