Guide to Building a Shed Base: Materials, Construction & Options | Shedstore [UPDATED]

Building a shed base is a crucial step in ensuring the stability and longevity of your shed. In this comprehensive guide, we provide detailed tips and advice to help you construct a solid foundation for your shed. From choosing the right shed foundation options to proper ground preparation and drainage considerations, follow our expert shed base building advice to create a durable and reliable shed base that will stand the test of time.

Editor’s Note [17.08.23]: Our guide to building a shed base was originally published on March 23, 2017. This version of the article is a major upgrade with content having increased six-fold. Please browse through the article below to read this extensive guide.

Choosing the ideal location

Selecting the right location for your shed base is a crucial first step in building a sturdy and long-lasting structure. A well-chosen location ensures the shed is both functional and aesthetically pleasing within your outdoor space.

Factors to consider

When deciding on where to build a shed base, numerous factors should be considered. Firstly, consider the purpose of the shed and its proximity to other structures or features in your garden. Ensure there is ample space around the shed for easy access and future maintenance. Take note of the terrain and landscape, avoiding areas prone to waterlogging or excessive runoff.

Also, consider the direction of sunlight to maximise natural light and minimise potential dampness inside the shed. Be mindful of any local building regulations or homeowners' association guidelines that may dictate where you are allowed to place your shed. Additionally, think about how the shed's location may impact the overall aesthetics of your garden or outdoor space.

Importance of a well-drained area

A level and well-drained area are essential for the shed base to provide a stable and solid permanent foundation. If you build a shed base on uneven ground or sloping ground may lead to structural issues and instability over time. A flat surface prevents the shed from tilting or sinking, ensuring doors and windows operate smoothly. Adequate drainage is crucial to prevent water from pooling around or under the shed, which may cause rot and damage to the base and the shed itself. By selecting a well-drained location, you will significantly extend the lifespan of your shed and protect your investment overall.

Preparing the ground for the shed base building

Before you build a shed base, proper ground preparation is essential to ensure a stable and durable foundation. Taking the time to prepare the ground correctly will contribute to the overall longevity and performance of your shed. Below are step-by-step instructions for preparing the ground for a garden shed and other types of garden buildings.

1)    Clear the area

Begin by clearing the area where you plan to build the shed base. Remove any existing vegetation, such as grass, weeds, or plants, to create a clean and level surface. This step is crucial as vegetation might cause unevenness and hinder proper drainage.

2)    Measure and mark

Measure the dimensions of your shed to determine the exact location of the base. Use stakes and string to mark the corners and outline of the base. Double-check the measurements to ensure accuracy.

3)    Level the ground

Using a shovel, rake, or a levelling tool, start levelling the ground within the marked area. Remove any high spots and fill in any depressions to achieve a flat surface. This step is vital for preventing water pooling and ensuring a stable base.

4)    Add a weed membrane

Lay a weed membrane over the levelled ground to prevent weed growth and maintain a clean surface for your shed base. The damp-proof membrane acts as a barrier, reducing the chance of weeds penetrating the base and causing damage over time.

5)    Compact the soil

To enhance the stability of the shed base, compact the soil using a tamper or a plate compactor. This will help to settle the ground and prevent any future sinking or shifting of the shed base.

6)    Consider drainage

Assess the natural drainage of the area to avoid water accumulation near the shed. If needed, create a slight slope away from the shed to direct water away from the base. Adequate drainage will protect the base and the shed from potential water damage.

7)    Check for levelness

Use a spirit level to check the levelness of the prepared ground. Ensure all sides are even and adjust if necessary. A firm and level base is crucial for the stability and proper functioning of the shed.

Man preparing a concrete shed baseMan preparing a concrete shed base

The importance of a shed base

The importance of a shed base cannot be overstated when it comes to shed base building. A properly constructed base provides a stable and level platform for the shed, ensuring structural integrity and preventing issues like water damage, rot, and uneven settling over time.

What does a shed base do?

Shed bases, whatever they are made from, need to achieve three things:

  1. The first is to make the ground level.
  2. The second is to support the weight of your shed.
  3. The third is to allow air circulation beneath the shed.

It is a false economy to build a shed base directly on the soil. The soil will inevitably move, causing the shed to tip, slope, and slant. The door will not open or shut correctly and, if made of wood, water will ingress causing premature rotting. You need a shed base and it’s best to do it before your shed goes down.

Shed base materials

When building a shed, selecting the right type of shed base is crucial for its stability and longevity. There are various shed base options available for shed base building, each with its own set of advantages and considerations. We discuss the various shed base materials below:

Concrete or paving slabs

Concrete and paving slab bases are popular choices for sheds and other garden building bases due to their durability and stability. A dry mixed concrete foundation base provides a solid and even surface that will support heavy sheds. Concrete slabs are a durable material, but a downside is that they normally require professional installation and curing time. On the other hand, paving slabs offer a DIY-friendly option, allowing for easier adjustments and replacements. However, they may be less suitable for heavier sheds and require regular maintenance to avoid shifting or sinking.

Paving slab shed basePaving slab shed base

If your shed has floor bearers (pressure treated pieces of wood attached to the bottom of the shed), you can place your shed directly on concrete blocks or pavement slabs. The bearers will help protect the shed from moisture damage and create space for air circulation. Any mortar must be fully set or 'gone off' before any weight is placed on top of it. Mixing concrete and laying paving slabs can be a time-consuming and messy job. 

Both concrete or paving slab shed base options offer excellent weed resistance and are long-lasting, but the cost and labour involved in each may influence your decision. This is why many people opt for wooden or plastic bases that are easier and quicker to lay.

Wooden Shed BaseWooden Shed Base

Wooden shed bases

These are basically a wooden frame for the bearers to sit upon and is a versatile and cost-effective option. They are relatively easy to construct and provide natural drainage for the shed. Wooden bases offer good support for smaller and lightweight sheds, but they may not be as sturdy as concrete or paving for larger structures.

In each corner, there are spikes which are inserted into the soil to create a stable, level base ready for your shed. Make sure you check that it is fully level before you place your shed on top.

Proper treatment and maintenance are essential to prevent rot and decay over time, especially when exposed to moisture. Timber frame bases are a great choice if you prefer a DIY project and want a more budget-friendly option for your shed.

ProBase Plastic Shed BasesProBase Plastic Shed Bases

Plastic shed bases

A very popular option, due to its ease is a plastic gridded shed base. Made from recycled materials, they offer excellent water drainage and are resistant to rot and decay. The interlocking design makes assembly straightforward, and they are easily repositioned or expanded if needed. Plastic bases are particularly well-suited for smaller sheds and provide good stability for lightweight structures.

In combination with shingles, these create a level surface for the bearers to sit upon. The shingle aids water drainage too. Plus, it can be reused if you move your shed. However, they may not be as suitable for heavy or large sheds, as they lack the same load-bearing capacity as concrete or a wooden base. Consider the shed's size, weight, and intended use when opting for plastic as a suitable material.

Shed BaseShed Base

Building a Shed Base

Building a shed base is a crucial step in creating a stable and long-lasting foundation for your shed. Follow this step-by-step shed base building guide to construct the ideal shed base that suits your needs, whether the shed base materials are concrete, paving slabs, wood, or plastic.

Common to all – rather than list this four times, the first common process is:

  • Mark the Area - Measure and mark the shed's dimensions on the ground using stakes and string

Concrete shed base construction

Here are the steps to construct concrete shed bases:

  • Excavate the area - dig a trench for the concrete slab, ensuring it is at least 4 inches deep
  • Add gravel - fill the trench with a 2-inch layer of compacted gravel for proper drainage
  • Create a formwork - construct a wooden formwork to contain the concrete, ensuring it matches the shed's dimensions
  • Mix and pour concrete - prepare the concrete mix according to the manufacturer's instructions and pour it into the formwork
  • Level and smooth - use a screed board to level the concrete surface and smooth it with a float
  • Allow curing - let the concrete cure for at least 48 hours before proceeding with shed installation
Concrete shed baseConcrete shed base

Paving slab shed base construction

Here are the steps to construct a paving slab shed base:

  • Excavate the area - dig a trench for the slabs, ensuring it is at least 2-3 inches deep
  • Add sand and compact - fill the trench with a 1-inch layer of sand and compact it to create a solid base
  • Laying - start laying the slabs in the desired pattern, ensuring they are level and evenly spaced
  • Adjust and align - use a rubber mallet and a spirit level to adjust the slabs and align them perfectly
  • Fill gaps - fill the gaps between the slabs with fine sand, ensuring they are securely locked in place

Wooden sheds base construction

Here are the steps to construct a wooden/timber-framed shed base:

  • Dig holes for posts - dig holes at the corners and intervals for the wooden posts, ensuring they are at least 2 feet deep
  • Insert posts - place the wooden posts in the holes and backfill them with concrete to secure them
  • Add gravel foundations - fill the area with compacted gravel to create a level and even surface
  • Attach bearers - attach pressure-treated bearers to the posts, ensuring they are level and evenly spaced
  • Install shed floor joists - position and fix the floor joists onto the bearers, ensuring they are securely attached
  • Lay flooring - lay the shed flooring on top of the floor joists, securing it with screws or nails

Plastic shed base construction

Here are the steps to construct a plastic shed base:

  • Excavate the area - dig a trench, ensuring it is level and free of debris
  • Lay the plastic grids - start laying the interlocking plastic grids in the designated area
  • Connect the grids - connect the grids securely to form strong underpinning for the shed
  • Fill with gravel - fill the grids with pea gravel to create a solid and well-drained surface

Shed base options - important considerations

It is vital to ensure that the following are seriously considered when installing a shed base:

1)    Ensuring stability and durability

Whichever of the shed base options you choose, a stable and durable shed base is crucial for the longevity of your shed. To achieve this, reinforce the base by using suitable shed base materials and techniques. Also, ensure proper compacting and levelling during construction to prevent any shifting or sinking over time.

2)    Allow for proper drainage

With all shed foundation options, proper drainage is essential to protect your shed from water damage and potential rot. Consider the natural slope of the terrain and implement drainage solutions, such as gravel layers or gutter systems, to direct water away from the shed and its base, ensuring a dry and secure environment for your belongings.

Shed base installationShed base installation

Common mistakes to avoid

Building a shed base requires careful planning and execution. Avoiding common mistakes will save time and effort, and ensure a successful and long-lasting shed, built upon a solid foundation.

Common mistakes to avoid when building a shed base

Mistake type Mistake description Tips on how to avoid
Measurement Incorrectly measuring the dimensions of the shed base Double-check all measurements and use stakes and string for accurate marking
Levelling Failing to level the ground properly Use levelling tools, to achieve a flat and even surface
Drainage Neglecting to consider proper drainage Assess the natural drainage and create a slight slope away from the shed for water runoff
Weed Control Not using a weed membrane or inadequate weed control Lay a weed membrane to prevent weed growth and maintain a clean base. Regularly check for weed infiltration
Compaction Insufficiently compacting the soil Use a tamper or plate compactor to ensure a solid and stable ground for the shed base
Rushing Hastily assembling the shed base without proper preparation Take your time with ground preparation and follow step-by-step instructions for a well-constructed base
Material Using unsuitable or low-quality shed base materials Invest in quality shed base materials that are suitable for the size and weight of your shed

Plastic ProBASE shed bases from Shedstore

At Shedstore, we exclusively offer a range of high-quality plastic bases sold in easy-to-assemble kit form. This range also features bases for log cabins. Appearances are deceptive, as these bases may be light, but they boast remarkable strength and durability. To ensure optimal performance, it is essential to carefully follow the shed base kits' instructions during installation.

For larger sheds, the bases require filling with pea gravel to provide added stability. If you have purchased our shed installation services, please ensure that the plastic base installation is completed beforehand. With our reliable plastic shed bases, you will create a sturdy and long-lasting foundation for your garden shed, guaranteeing years of worry-free storage and enjoyment.

Our ProBASE range is eco-friendly and comes in an extensive range of sizes from 5’x’4 to 13’x23’. Explore them here. Call us if you are unsure, as these bases will not be suitable for every type of garden building.

Article recap

Building a solid shed base is essential for the stability and longevity of your shed. This comprehensive guide has covered various shed foundation options, including concrete, paving slabs, wood, and plastic. Carefully selecting the ideal location and ensuring proper ground preparation and drainage are vital steps to create a durable foundation.

By avoiding common mistakes and following the step-by-step instructions, you can build a sturdy shed base that will protect your shed and its contents for years to come.

The spirit level is your most important tool, no matter what shed base you choose.

Investment in a quality shed base is an investment in the longevity of your shed. It just quietly gets on with its job - an essential one at that. Shop our range of garden sheds here

Shed built on plastic baseShed built on plastic base

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