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A wooden garden shed under construction standing on a concrete foundation in the garden.

Building a Shed Foundation (2024 Guide)

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Author Icon By Angela Bunt Updated 01/14/2024

Building a sturdy shed foundation is crucial for helping it withstand the elements and remain level over time. Learn about your various shed foundation options, how to prepare and choose the best type, and an overview of the steps involved.

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Depending on severity, leak repair can range from $2,000–$7,000.

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The average cost for sinking foundation repair ranges from $500–$3,000.

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How To Prepare

Consider the preparation process before you begin. You’re not ready for a Lowe’s trip to gather materials until you know what’s required to get started. 

  • Apply for building permits: Check with your local permit office to see if you need one to begin construction. You may also have to get a city or county inspection to approve the final foundation and shed if required.
  • Determine shed location: Consider your local climate and where on the property you’ll install your shed foundation.
    • Climate: Snowy, wet regions require additional considerations. You should consider the snow’s weight, the water’s flow, and drainage.
    • Soil type: Your soil type can affect what you need to build. For example, clay expands and shrinks according to rainfall. You’ll need a proper base if you’re considering a concrete slab or blocks on top of it.
    • Utility lines: Have your county spray for utility lines so you know where you can dig. You may have to choose a skid foundation if utility lines run through your work area.
    • Frost line: Colder areas have deeper frost lines. Check with local building codes to determine how far you must dig when installing posts. 
    • Landscaping: You want 3–4 feet of clearance between your shed and existing structures. You must keep permanent landscaping in mind when mapping out where you want your shed to go. 
  • Consider shed size and type: Smaller sheds may not need a foundation. You also won’t want a permanent foundation if you eventually plan on moving the shed to another location. Instead, consider one that you can easily deconstruct.

How To Choose a Type of Shed Foundation

There are many things homeowners should consider before choosing a foundation type. Beyond budget, consider:

Climate: Does your area receive a lot of snowfall every year? You must consider that extra weight if it does.
Drainage: How will you prevent water from pooling around and within the shed itself when it rains?
Local building codes: Local building codes may require you to build a certain type of foundation. This is especially true if your area regularly goes below freezing in winter. Frost-proof foundations require different building materials and methods. 
Shed purpose: Is it simply a shed for garden tools, or are you looking to store heavy machinery?
Shed weight: The timber frame’s weight may prove too much for some foundation types. Small sheds may also not need a foundation unless you want a specific type of shed floor.
Slope: Is the build location hilly, or does it have a noticeable slope? The uneven ground may require you to choose one foundation over another. 
Soil type on build location: The soil type on the build location may help dictate what you need to build. For example, living in an area with rocky soil requires less foundation than in an area with clay soil.
TypeCost RangeSloped Sites?Frost-Proof?

Concrete blocks

$15–$30 per square foot

Some slope is OK

No

Concrete piers

$6–$12 per square foot

Yes

Yes

Concrete slab/ concrete pad/ concrete foundation with footers

$5–$25 per square foot

Yes

Yes

Deck blocks

$12–$25 per square foot

Some slope is OK

No

Floating concrete slab on-grade foundation

$4–$8 per square foot

Yes

Yes, but may require additional work

Gravel pad/gravel base/gravel foundation

$800–$2,000

Yes

Yes, but may require additional work

Pavers

$8–$50 per square foot

No

No

Permeable concrete pavers

$10–$30 per square foot

No

No

Post and beam

$6–$12 per square foot

Yes

Yes, but may require additional work

Screw piles

$15–$30 per square foot

Yes

Yes

Skid foundation

Varies. Cost of pressure-treated lumber depends on location and seller.

No

No

*Cost data via Angi, Fixr, HomeGuide, and Lowe’s.


Steps to follow

The steps to a sweet shed involve the following:  

Step 1: Lay Out the Shed Area

The first step is to choose a location for your shed. Ideally, you’ll want a spot close to being level that doesn’t collect water when it rains. You’ll want to ensure you have at least 3 feet of clearance if you’re building near a fence, and you’ll want 4 feet or more if your shed is larger than 160 square feet. 

Use mason lines and batter boards to lay out the exact dimensions of your future shed. 

Step 2: Square the Area

You need to measure 3 feet along one mason line and 4 feet along a corresponding line to ensure your area is perfectly square. The distance between the two should be 5 feet if your work area is square. You’ll need to adjust your string if it’s not. Do this with every corner. Remember that adjusting a line on one side will affect your other corners.

Step 3: Install Posts

Installing posts can be easy or difficult. It may be the hardest part if you have rocky soil. 

You can rent a post-hole digger from many hardware stores. It will make the process slightly easier, but you can also use a post-hole digger. A post-hole digger is easier to handle but will take longer. The power tool route may feel like a two-person job, but the work will fly by. 

The holes should be 4 feet apart and 12 inches below the frost line. Pour at least 4 inches of crushed stone before pouring the concrete at the bottom of each post hole. Place your post on top of it and ensure it’s square before pouring additional concrete to secure it in place once it has cured. Add temporary bracing to the post as the second layer of concrete cures. 

Step 4: Trim Posts and Attach Post Brace Brackets

It’s too difficult to dig post holes that are level with one another, so even them out at the top instead. Determine how high you want your shed floor to be and mark one post to use as a guide for the others. Trim the tops with a saw as needed. Next, attach post brace brackets and install 4-by-4 runners.

Step 5: Build Floor Frame

Construct a floor frame on top of your 4-by-4 runners by using 2-by-4 planks. Measure each side twice to guarantee the frame is square. Secure the frame to each 4-by-4 one corner at a time once you’ve confirmed this. Have somebody hold the frame as you screw down each corner if possible. This makes the process faster while getting a more accurate final product.

Step 6: Lay Down Plywood

You can lay down plywood directly on top once you’ve completed your floor frame. Ensure it’s flush with the frame before nailing it down. Don’t move on until you double-check the foundation is level. Your foundation is complete if it is, and you can begin constructing the shed.


How To Hire a Professional

Building the best shed foundation may not be within your do-it-yourself (DIY) skill set even if you have extensive woodworking experience and read some shed how-to guides. You may need to lay down pea gravel, pour concrete, and make the ground level long before you even think about floor joists or framing. There’s no shame in hiring someone to build your shed base if any of this seems like too much. 

You can expect to spend between $50–$100 an hour in labor costs alone if you hire a professional. The amount of time it takes depends on your chosen type and size of foundation, so make sure to ask for a time estimate when getting a quote. 

Ensure you get at least three references and check that the contractor is properly licensed and insured before choosing a professional. It’s also important that the contractor has everything they need to complete the job. They may know how to do the work but may not have the necessary resources, such as specialized equipment or a helper, to make the leveling process easier. 

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Finally, make sure you feel compatible with the contractor. Having a good rapport with a contractor can help with any project. Problems may arise if neither of you knows how to communicate expectations.

Our Conclusion

The first step in successfully planning your shed foundation is to read any building codes that may dictate what you have to build. Next, consider what you truly need. It may not be necessary to build the sturdiest, hardiest foundation possible. Large sheds typically involve pouring and leveling concrete, while smaller sheds may just need to be raised slightly off the ground. 

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FAQ About Building a Shed Foundation

What is the best foundation for a shed?

The best foundation for a shed is debatable, but if you don’t mind a bit of work and have the budget, a concrete slab is the best permanent foundation for many homeowners. It’s solid, can hold lots of weight, and you can build it as large or as small as you need. The only downside is that you can’t pour the concrete during freezing weather and may have to build ditches to encourage water to flow away from the shed. 

What is the cheapest way to build a shed foundation?

The most affordable way to build a shed foundation is to make it on top of some large timbers to avoid direct ground contact. However, the drawback is you may have to do yearly repairs and deal with more pests than usual. Wood is also susceptible to rot over time regardless of how treated it is. 

What are the benefits of a shed foundation?

There are many benefits of a shed foundation. In general, a foundation helps your shed with drainage and stability. A proper foundation can also help your shed be more aesthetically pleasing, and this helps with resale value if you plan to sell your home.

What is a frost line?

A frost line is the depth at which groundwater freezes. Building foundations must extend below this level since the soil above the frost line expands and contracts as temperatures fluctuate. The repetitive freezing and thawing cycles can damage the structure if the foundation doesn’t reach past the frost line. Properly embedding foundations below the frost line helps ensure the stability and longevity of permanent buildings.

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