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how to build the shed foundation

How To Build A Shed Foundation (or a Shed Base)

So you've decided to buy a shed for sale, and now you're wondering how to create a solid foundation for it. In this article, we'll guide you through choosing the right foundation and location for your shed, as well as the different types of foundations available. We'll also provide a step-by-step guide on building the perfect foundation, ensuring your shed stands strong for years to come.

But before we jump into the nitty-gritty, let's take a moment to understand why a shed foundation is so crucial. A well-built foundation not only provides a level and stable base for your shed, but it also helps protect it from moisture, pests, and other damaging elements. Plus, a good foundation can significantly extend the life of your shed.

Key Steps To Build A Shed foundation

  1. Select the right location and choose the type of foundation that best suits your needs. 
  2. Prepare the ground by removing any grass, rocks, or debris, and leveling the area as needed.
  3. Install your chosen foundation, making sure it's level and secure.
  4. Finally, level and square it off by ensuring all corners are at right angles and the entire structure is level.

On-Grade Foundation vs. Frost-Proof Foundation

Designs vary significantly, but primarily fall into two groups: floating (or on-grade) and permanent (or frost-proof) foundations.

Floating Foundations

Also known as on-grade foundations, floating foundations rest directly on the ground. Their simplicity makes them an appealing choice; they are straightforward and fast to construct without the need for excavation or concrete pouring. These foundations are typically suitable for most small to medium-sized sheds.

Permanent Foundations

In contrast, permanent foundations, also referred to as frost-proof foundations, demand a more complex construction process but offer increased durability and longevity. These foundations are ideal in colder climates prone to frost heave. They are typically constructed using concrete footings, piers, or a monolithic slab, although pole-barn construction can also be employed, involving the use of tall poles or square posts planted deeply in the ground. Permanent foundations are especially suitable, and often legally mandated, for larger sheds.

Examination of the ground conditions and drainage

You'll want to carefully assess the ground conditions and drainage to first. Proper examination of these factors will help you avoid issues such as water damage, structural instability, and unwanted maintenance costs. Before you begin construction, take the time to thoroughly examine the area and address any potential problems.

  1. Soil type: Different soil types have varying levels of stability and drainage capabilities. Sandy or gravelly soils tend to have good drainage, while clay soils can retain water and cause problems. You may need to consult a professional to determine the best foundation type for your specific soil conditions.

  2. Slope: Ideally, your shed foundation should be built on a level surface. If the ground has a slope, you may need to excavate or build retaining walls to create a level area for your foundation.

  3. Drainage: Good drainage is essential to prevent water from pooling around and potentially causing damage. Make sure the area has proper grading and consider installing a drainage system if necessary.

  4. Groundwater level: Be aware of the groundwater level in your area, as a high water table can cause issues. In such cases, you may need to consider alternative foundation options or consult a professional for guidance.

Type of Shed Foundations

Now that you've decided to build a shed, it's time to explore the various types of shed foundations available to you. From concrete blocks and pavers to gravel, timber-frame, and plastic grid options, each offers its own set of benefits and drawbacks.

Concrete Blocks

While concrete blocks may seem like a quick and easy solution, they can actually cause long-term issues with your shed's structural integrity and may even void warranties.

A concrete block foundation may be cheap and easy to install, but it doesn't provide equal support to all parts of your shed, leading to potential problems such as sagging floors and binding doors or windows. Additionally, concrete blocks are generally not recommended for use in frost-prone areas, and they can make anchoring your shed more difficult.

When considering how to build a shed base, it's important to be aware of the drawbacks of using concrete blocks. Here are three key reasons why you might want to choose something different:

  1. Uneven support: Concrete blocks don't support all parts of the shed structure equally, which can lead to issues such as sagging floors and binding doors or windows.

  2. Challenging conditions: Concrete blocks can result in precarious shed placements, especially on slopes, and they're generally not suitable for use in frost-prone areas.

  3. Warranty concerns: Using a concrete block foundation may void the warranties of some prefabricated sheds, so it's important to check with the manufacturer first.

Paver Foundation

Pavers offer a visually appealing and relatively affordable option for creating a solid base under your small outdoor structure. The simplicity of a paver foundation makes it an excellent choice for DIYers who want to take shed construction into their own hands. By providing a stable base for your shed, pavers help distribute the weight of the structure evenly across the ground, ensuring that all parts of the shed are well-supported.

Start by determining the size and shape of your shed, and then follow these steps to create a level and sturdy base. As you work through the process, keep in mind the the flatness of using pavers and make adjustments as needed to ensure the best possible outcome for your project. Here's a table to help guide you through the process:

Step Description
1 Mark the area where the shed will be built, ensuring it is level and free of debris.
2 Excavate the area to a depth of about 6-8 inches, depending on the size of the pavers you'll be using.
3 Add a layer of compacted gravel or crushed stone (about 4 inches thick) to provide a stable base for the pavers.
4 Lay the pavers in your desired pattern, making sure they are level and evenly spaced. Use a rubber mallet to tap them into place.
5 Fill the gaps between the pavers with sand or polymeric sand, and then compact the entire surface with a plate compactor or hand tamper.


By following these steps, you'll create a durable and attractive paver foundation that will support your shed construction and provide a stable base for years.

Gravel Pad

A gravel pad is typically made from crushed stone, like limestone, which provides a stable base for your shed while also allowing for proper drainage. This type of shed foundation option can be easily customized to accommodate sloped sites, ensuring that your shed door is at ground level for easy access.

Start by marking out the area where your shed will be placed and remove any grass or topsoil. Dig down to a depth of about 4-6 inches, ensuring the area is level and compact the soil.

Next, add a layer of landscaping fabric to prevent weeds from growing through the gravel. Then, pour crushed stone into the excavated area, filling it to the desired height and ensuring it's evenly distributed. Compact the gravel using a plate compactor or tamper to create a solid, stable base for your shed.

Finally, make any necessary adjustments to ensure the foundation is level before placing your shed on top. With proper installation and maintenance, a gravel shed foundation is an excellent and economical choice for supporting your new storage space.

gravel pad


The second most popular choice: timber-frame foundations. These foundations are not only easy to build but also provide versatility in terms of flooring options.  Follow these four simple steps:

  1. Choose the right materials: Opt for pressure-treated lumber that's rated for ground-contact use to ensure your timbers don't rot prematurely. You can use 4x4s, 4x6s, or 6x6s for the frame, and 2x8 boards for the outer contour and inner joists.

  2. Construct the frame: Create a rectangular frame by joining the timbers together using half-lap corner joints or stacking them two or three high and fastening them with structural screws or long landscaping spikes. If your site isn't pre-leveled, you may need to use 6x6 timber supports with an average length of 3 feet to compensate for any slope.

  3. Install the floor: Fill the floor space within the frame with your choice of flooring material, such as bricks, concrete, gravel, marble chips, or bluestone slabs. Alternatively, you can screw down pressure-treated decking for a simpler option.

  4. Build the shed walls: Once your timber-frame foundation is complete, proceed with constructing the walls of your shed on top of the frame.

By following these steps, you'll have a sturdy and long-lasting timber-frame foundation for your shed that can easily accommodate various flooring options.

Plastic Grid

If you're looking for a more environmentally friendly option that's still easy to install, consider using a plastic grid system for your shed base. These systems are made from recycled materials and provide a solid foundation for your shed while allowing for proper drainage.

First, you'll need to level the ground and prepare the site, just as you would for other shed foundation types. Once the site is prepared, simply snap the plastic grid pieces together, place them on the ground, and fill the grid with gravel to create a stable, permeable base for your shed.

Installation of a plastic grid is relatively simple and requires minimal tools. Start by digging out the area where your shed will sit and leveling the ground. Lay down a layer of geotextile fabric to prevent weeds from growing under your shed and to help with drainage.

Then, assemble the plastic grid according to the manufacturer's instructions, ensuring that it covers the entire area of your shed. Finally, fill the grid with gravel and compact it to create a strong, stable surface for your shed to rest on.

Concrete Slab

A concrete slab is an excellent and the most popular choice for a shed foundation due to its ability to support all parts of the shed evenly and its adaptability to sloped sites. However, be prepared for the cost and labor involved, as this type of foundation is the most expensive and s labor-intensive option.

To build a concrete slab shed foundation, follow these key steps & tips:

  • Prepare the site by clearing any vegetation and leveling the ground. Ensure proper drainage by sloping the ground away from the shed location.

  • Construct a form for the concrete slab using wooden boards. These boards should be at least 2 inches taller than the thickness of the slab you plan to pour.

  • Install a layer of compacted gravel or crushed stone to provide a stable base for the concrete. Ensure this layer is level and slopes away from the shed location for proper drainage.

  • If your site is sloped, you may need to install a retaining wall or use additional materials to support the concrete slab.

  • Incorporate reinforcement, such as rebar or wire mesh, into the slab for added strength.

  • Pour the concrete, taking care to level it within the form and eliminate any air pockets.

  • Allow the concrete slab to cure for a minimum of 7 days before placing the shed on the foundation.

By investing in a concrete slab, you're ensuring the shed lasts for years and providing a solid base for anchoring. Keep in mind, though, that drainage can be a concern if your shed has wooden flooring, joists, and skids, so it's essential to plan accordingly for the best results.

concrete slab foundation

Building The Best Shed Foundation

Preparing the Ground

It's crucial to prepare the ground properly, ensuring it's level and free of debris to create a stable base for construction. Start by selecting a suitable location for your shed, considering factors such as accessibility, drainage, and exposure to sunlight.

Once you've chosen the ideal spot, clear the area of any rocks, roots, and other debris. Use a shovel or a rake to remove any grass or vegetation, leaving only bare soil. To ensure the construction is level, use a long straightedge and a spirit level to check the ground surface. If necessary, add or remove soil to achieve the desired levelness.

After you've cleared and leveled the area, it's time to compact the soil to create a firm base for constructing a shed foundation. Rent a plate compactor or use a hand tamper to compact the soil evenly across the entire surface. This will help prevent the foundation from settling unevenly over time and ensure the shed remains stable.

If your chosen location has poor drainage or is prone to erosion, consider installing a layer of gravel or crushed stone to improve stability and drainage. By carefully preparing the ground, you'll make the construction process easier.

Building the Foundation

First, choose the type of shed foundation you want to build. There are several options, including concrete slabs, concrete blocks, and wooden skids. Concrete slabs provide a solid, level surface that is ideal for larger or heavier sheds.

Concrete blocks are a more economical option, providing support for the shed's corners and walls while still offering some flexibility in leveling. Wooden skids are a popular choice for smaller, lighter sheds and can be easily adjusted as the ground settles over time. 

Once you've selected the appropriate foundation type, follow the specific guidelines and recommendations for building the foundation to ensure your shed remains level and secure for years to come.

Allowing the Foundation to Settle

Give your newly constructed base some time to settle and adjust, as this essential step helps the materials to bond and adapt to the ground, creating a solid and durable base for your shed.

Depending on the type of foundation you've built, this process can take anywhere from a few hours to several days. Concrete foundations, for example, require at least 24 hours to cure, while gravel or paver bases may need a day or two to settle.

During this waiting period, avoid placing any heavy objects or walking on the foundation, as this can cause it to sink or become uneven. Instead, use this time to double-check your measurements, ensure the foundation is level, and make any necessary adjustments.

Once the foundation has settled and is properly aligned, you can confidently move on to constructing your shed, knowing that it has a strong and stable base to support it.

Comparison Table Of All Foundation Types

Foundation Type Cost (Materials + Labor) Frost-proof? Sloped Sites? Notes
Skid Foundation $ No No Not technically a foundation.
Metal Foundation Kit $$ No No Available for only specific sheds.
Metal Jacks $$ No Small slope Relatively new option; for small sheds only.
Concrete Blocks $$ No Small slope Popular option; not great for durability.
Pavers $$$ No No Good for small sheds on flat site.
Plastic Grid (Permeable Pavers) $$$ No No Relatively new option; good for flat sites.
Deck Blocks $$$ No Small slope Usually combined with post-and-beam.
Gravel (Crushed Stone) Pad $$$ With modification Yes Best all-around option.
Screw Piles $$$ Yes Yes Requires special equipment for install.
Post-and-Beam $$$ With modification Yes Popular option; raises shed height.
Concrete Piers $$$ Yes Yes Simple frost-proof option.
Concrete Slab (floating) $$$$ With modification Yes Durable, but labor intensive and expensive.
Concrete Foundation w/ Footers $$$$$ Yes Yes Overkill except for garages and very large buildings​​.


Frequently Asked Questions

1. What is a concrete pier in terms of shed foundations?

A concrete pier is a type of foundation used to build a sturdy and durable shed. It involves casting concrete into hole forms in the ground and can be used 1-5 times during the shed floor construction. We usually recommend you go with a full slab if you are already going to pour concrete.

2. How does slope impact the foundation of a shed?

A slope can make the shed site uneven. Building a shed foundation on uneven ground requires additional attention to ensure the shed is level and secure.

3. What is a skid foundation?

A skid foundation involves laying down a series of "skids" or beams on the ground on which the shed sits directly. It is a common foundation for a wood or metal shed, used 1-3 times depending on the weight of the shed.

4. Are deck blocks a viable shed foundation option?

Yes, deck blocks can be used 1-4 times as an on-grade shed foundation option. They offer a firm foundation and are ideal for smaller, lighter storage sheds.

5. Can I build a shed foundation on uneven ground?

Yes, it's possible to build a shed foundation on uneven ground. Techniques such as using deck blocks or metal shed jacks can help level the shed.

6. What are some of the most common types of shed foundations?

Some common types of shed foundations include concrete piers, slab foundations, skid foundations, and deck blocks. The choice often depends on whether you're building a wood shed, plastic shed, or metal shed.

7. What factors determine the type of foundation I need for my shed?

Factors include the type of shed (storage, garden, concrete, etc.), weight of the shed, local building codes, and ground conditions at the shed site.

8. Can I DIY the construction of the shed foundation? 

Yes, you can DIY the construction of your shed foundation. However, for larger projects or specific types like a concrete shed foundation, you might need professional help due to the complexity and labor involved.

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About The Author

Andy Wu - Resident Expert

Andy Wu - Resident Expert

Andy Wu is the resident backyard products expert and hails from Atlanta, Georgia. His passion for crafting outdoor retreats began in 2003.

As a fellow homeowner, he founded Backyard Oasis to provide top-quality furnishings and equipment, collaborating with leading manufacturers.

His main focus is on sheds and generators!

In his spare time he like to hike the tallest mountains in the world and travel with his family.

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