Building a Shed Base: A Step-by-Step Guide

If you’re thinking of adding a garden shed to your backyard, you’ll want to know how to build the base. The same applies if you’re installing a log cabin; there are four steps you need to take.

This guide will take you through a simple step-by-step process of constructing shed bases. It covers everything from site preparation and positioning to foundation options and more. Read on!

Step 1: Plan Where Your Shed Will Go

BillyOh Super Saver Overlap Apex Shed
BillyOh Super Saver Overlap Apex Shed

It may surprise you that the first step of building a shed floor base doesn’t have anything to do with the building. Before you even think about choosing one, you need to weigh up your options. And that means deciding where to put the structure itself.

Below, we’ve come up with some areas to consider, but to get an overview:

  • Make sure there’s clear access for delivery and maintenance work.
  • Consider the state of surrounding plants and what you might want to grow.
  • Consider things like the view of your garden, how easy it’ll be to run electricity etc.

Now, let’s break those points down into sections.

1. Surface

As well as suitable materials for the shed base, you need the right surface. We’ll get onto level ground in a moment, but for now, just know that a good surface:

  • Won’t be an area of pooling groundwater.
  • Won’t be at the bottom of a slope or by a ditch
  • Won’t be rocky.

And to tick all these boxes, you’ll need to consider…

2. Your garden

Consider the slope of your garden in relation to your home’s layout when planning your shed. Optimal natural light exposure should also be factored in for the placement. A strategic location ensures ample sunlight throughout the day. This aids plant growth and creates a pleasant atmosphere.

Remember, the foundation is just the beginning. Anticipate future needs and functionalities to maximise the shed’s utility. By planning ahead, you can ensure a sturdy foundation and ideal positioning for your shed.

3. Location

BillyOh Garden Bar Shed
BillyOh Garden Bar Shed

Place the outdoor storage shed where it receives ample natural light. For workshops, choose a location protected from harsh weather, ensuring comfort and longevity. Another tip is to opt for spots with refreshing breezes during the warmer months. Smart placement of garden structures enhances their year-round use and enjoyment.

4. Uneven ground

To ensure your shed base kit remains level, the first step is creating a level surface. Chances are, your natural terrain won’t be perfectly level. You’ll need to raise or lower it, as we’ll explore shortly.

The initial task involves levelling the area where your garden structure will stand. Depending on the tools at your disposal, this can be achieved with tools ranging from a loam leveller. Alternatively, use a garden rake or a wacker packer.

Step 2: Select the Type of Shed Foundation

Now that you’ve got a level and marked-out area to work with, you need to settle on a type of foundation.  From concrete to a gravel-filled base, your choice may vary depending on the size of your garden storage shed. It may also depend on the material of your building, for example, if you have a metal shed instead of a timber one.

1. Timber frame

BillyOh Wooden Shed Premium Tongue and Groove Floor
BillyOh Wooden Shed Premium Tongue and Groove Floor

A wooden shed floor is one of the most popular and economical types of base kits. Simply made of straight pieces of timber, cut to size and assembled within a wooden base. It offers a sturdy base and raises your shed away from the moist ground.

Floor joists can then be laid on top and nailed or screwed into these timber bearers. At each corner of the timber base, simply drive stakes into the ground and secure them to the wooden frame. This will ensure your shed base doesn’t move when building on it.

2. Concrete base

A concrete floor is a much more permanent solution. But it’s also more expensive. With a permanent foundation, you’ll be able to raise your garden shed up from rising dampness and provide a long-lasting base.

A concrete foundation may require some more expertise or even hiring someone to pour it, however. These sorts of jobs do require cement mixers, at the very least!

To pour your own concrete slab, you’ll need to:

  • Level the shed site
  • Set up boxing around the pour perimeter
  • Lightly soak the ground
  • Mix and pour the concrete
  • Screed and levelled the slab
  • Trowel any edges
  • Allow it to dry, and brush it

For a more in-depth explainer, check out the video below:

3. Paved base

A more cost-effective alternative to a concrete slab would be to use pavers. Paving stones are a particularly good choice for a plastic shed base.

Simply level your site (like in step 1) and either assemble from your backyard or buy, some pavers. Dig out shallow footings at each corner of your site (and in the middle of each side of your shed to be on the safe side).

Using builder’s sand, fill the footings with compacted sand and sink the pavers into them. Check that they’re level across the whole site and then you can add a layer of soil over them.

4. Damp proof membrane

For a seriously solid ground base, you might want to consider installing a damp-proof membrane.

This durable material (also known as a weed membrane) will not only protect your shed floor from water ingress but from weed growth. Damp-proof membranes can be sunk beneath concrete or gravel foundations like pea gravel.

Bases for metal sheds

Concrete slabs work particularly well for metal sheds as you can drill bolt holes into concrete. You can then position your shed and secure it to your slab.

Note: Whichever method you choose, we recommend that you have a 2” (5 cm) lip around the base of your shed. To calculate the size of base required for the particular building you wish to build, add 4” to the overall base dimensions, to ensure an adequate base size for your shed.

Step 3: Build Your Shed Base

Now that you’ve settled on your shed base “based” on:

  • Your budget
  • Your needs
  • Your garden shape, size, runoff
  • The size and weight of your proposed garden building
  • Your available tools and expertise

You can start by digging out your shed foundation. Begin your ground preparation from raking to remove any weeds, leaves, or other hazards. This will help avoid future deterioration to your shed’s base, especially if you install a weed membrane.

Next, mark out your shed site with stakes and a string line. This is a highly achievable task even if you’re not a DIY enthusiast! Continue to rake and level the area inside the string line.

This step will be the same no matter which foundation kits you use. Keep scrolling to see the next steps for concrete vs timber base.

How to build an Eze base

BillyOh Eze Base
BillyOh Eze Base

Most of our garden sheds come with the option to purchase an Eze base. This is our recommended base for most models due to its ease of installation.

The Eze is made up of a wooden floor surround, supported by wooden bearers which span the depth of the shed. It can be fixed into the soil or soft ground via sharp-ended wooden plinths, which are supplied with the base. Make sure that wherever you are planning to install it, the ground is level.

How to build a concrete shed base

You will need:

  • Pegs and string
  • Building sand
  • Standard cement (all-in ballast, cement & water)
  • Timber boxing
  • Concrete screed
  • Hand trowel
  • Tape measure
  • Spade
  • Sweeping brush

To get your concrete perfectly level you could always hire a laser, but this requires some previous knowledge and may be expensive. Still, concrete is great for larger sheds.

1. Mark Out Your Base

This is where you’ll be placing your garden shed. Make sure to plan for a 2m gap between the shed and any boundaries. Using pegs and string, mark out the base 2 inches (5 cm) larger than the area of the building on each side. Always be exact with your measurements and check the dimensions of your building first – you don’t want a 12x8 base for your 16x8 shed!

Remember to test the size by measuring the two diagonals to ensure the area is square.

2. Level off the Area

Concrete requires 3” (7.5 cm) of compacted hardcore (all-in ballast or other crushed rubble/gravel) underneath the 3″ concrete layer. The base can be level with the ground or raised above it.

If you want it to be level, excavate the top earth to 6” (15 cm), to allow for the hardcore layer and 3” (7.5 cm) of concrete. Level the area with a rake and spade and remove the pegs.

Ricky and Morty True Level

3. Level Your Hardcore

Set up your timber boxing. This involves measuring, cutting and fitting timber to the shape of the base in order to contain the concrete.

Check diagonal measurements to ensure your formwork is square and level as this will determine whether your shed base is 100% sturdy. Next, spread a layer of well-compacted hardcore (all-in ballast or crushed gravel) and cover with a liberal amount of sand.

This needs be well compacted and flattened down, preferably with a compacting tool or roller.

Man stood at cement mixer tipping it into wheelbarrow
Credit: Boel’s

4. Add the Concrete

Mix concrete using one part cement to five parts all-in-one ballast, or use bags of dry-mixed concrete and just add water.

Small amounts of water should be added at a time and mixed into the concrete. Be careful as excessive amounts may make the cement too sloppy and it needs to stay reasonably dry.

Spread the concrete evenly and slightly above the formwork. This can be then levelled off with a long straight edge of timber resting on the formwork. Use a sawing motion slowly over the entire surface of the freshly laid concrete.

If wet weather is forecast, cover the concrete with polythene for 24-hours. In warm weather, cover the base with damp sacks and sprinkle them with water over the 24-hour period, this will ensure the drying concrete will not shrink and crack.

The result will be a smooth, solid and level base – the perfect foundation for the construction of a garden shed.

How to build a paving slab shed base

You will need:

  • Pegs and string
  • Flat Face Paving Slabs
  • Building sand
  • Standard cement (all in Ballast, cement & water)
  • Rake
  • Tape measure
  • Spade
  • Rubber mallet
  • Sweeping brush

1. Mark Out Your Base

…where you will be placing your garden shed. Make sure to plan for a 2m gap between the shed and any boundaries. Using pegs and string, mark out the base 2 inches (5 cm) larger than the area of the building on each side.

Test the size by measuring the two diagonals to ensure the area is square.

2. Dig, Level off and Rake the Area

Strip the topsoil and dig out to a depth of approx. 2.5” (7 cm) to accommodate the base. Level the area with a rake and remove the pegs and string.

3. Mix the Cement

Mix together one part cement to eight parts building sand for a dry sand and cement mix. Spread this evenly, ensuring that the mix sits approx. 4 cm in depth. Be sure it is level.

4. Lay the Paving Slabs

Starting from one corner and working outward, lay the slabs by tapping down on the centre of each slab with a rubber mallet. Using a spirit level, ensure all the slabs are square, level and firmly butted together for a solid base.

dirty hand trowel on tiles
Credit: Unsplash

5. Double-Check the Base Is Level and Flat

The completed base should now be level and square. Conduct a final check with a long, straight-edged piece of timber to check if the base is level from each corner.

Also, measure the diagonals to finally check that the base is square. Brush off any excess dry sand/cement mix which could hinder the levelling of the shed. The result is a smooth, solid and level base.

Step 4: Shed Installation

BillyOh Expert Tongue and Groove Apex Workshop with Dual Entrance
BillyOh Expert Tongue and Groove Apex Workshop with Dual Entrance

Well done on finishing your shed base! You used materials like wood, bricks, concrete, or a special gravel base. Now, you’re all set to start putting together your garden building. It’s important to wait for the base to settle properly before you begin building on it. This helps keep everything stable and strong for a long time. Whether you’re making a storage shed or summer house, your careful planning means you’re off to a great start. Stick to your plans and use the solid base you’ve made to create a useful and cosy spot in your garden.

By following these steps, you’re making sure your building goes up smoothly and that you’ll enjoy it for a long time. Keep it up, and soon you’ll be enjoying your new outdoor space!


Building the garden shed base is generally a straightforward task. With the right tools and a guide like this, it can be completed by a single person. But when it comes to the actual assembly of the shed, having an extra pair of hands available to assist is ideal.

Our garden sheds for sale come as pre-measured and pre-cut panels, making assembly a breeze. With just you and friends, along with some basic tools, even a 2x10 metal shed can be put up in a matter of hours! Now that you know how to build the base, your next step is to: “How to Build a Shed”.

Shop The Master Apex Shed


1. Mark out your base with pegs and string line (with a 5cm overlap on each side)

2. Dig out, rake, and level the proposed area to a depth of approx. 7cm
3. Dig out pads for pavers at the four corners of your shed (and once more along each side)

4. Mix general purpose cement with sand and water and spread evenly in the pads approx. 4cm.
5. Sink pavers into these holes and level across the whole site

Concrete slabs: For metal sheds, heavier, and more permanent structures

Pavers: For a budget-friendly and easy DIY alternative

Timber sub-floor: For wooden sheds to raise them away from ground moisture

Ultimately, it will depend on your budget, shed type, and needs.


Mark out and level the proposed site of your shed. Build timber boxing (formwork) and raise/lower it to the desired height of your slab. Rake, level, and compact hardcore inside your timber boxing.


Mix and pour the cement and screed it as you go. Finish off any edges and corners with a hand trowel and allow to dry. Brush your slab to finish.

The easiest way to adjust the level of your shed base is to level the ground of your proposed site first. Start with a rough eye level using a rake or loam leveller and progress to using a spirit level. You can lay a level across, for example, pavers at opposite ends of your site or on top of timber boxing. If the distance is too great, run a string line between the two points to see where your site is low or high.

Absolutely. Building a shed directly on grass can lead to rising damp, weed ingress, rot, and even an unsafe structure. Building a shed on natural ground will be unlevel, causing uneven and undue stress on your shed which could shatter windows and warp doorframes. So not only do you need a shed base (timber sub-floor, pavers, concrete, gravel base), you also need a level base.