LP Outdoor Building Solutions

Learn how to prepare a shed foundation.

Why You Need To Build A Shed Foundation

Even if you plan to buy your shed pre-built, you'll still need to build a shed foundation–or hire someone to do so–before your new shed can be put into place. A proper shed foundation is important for two main reasons. First, the shed needs to sit on a stable, level surface for the structure to remain stable and for the door to operate properly. Secondly, the shed needs to sit slightly off the ground to allow for proper water drainage and minimize moisture transfer from the ground to the shed structure.

There are several types of shed foundations, and the kind you need may depend on where you live, the size of your shed and its intended use. The guidelines below are meant to give you a general overview of some of the most popular and successful DIY methods. Other types of shed foundations, including concrete slabs and poured footers, require professional installation.

Overview of How To Build A Shed Foundation*

Is the Site for Your Shed Already Level?

(If the site grade has elevation differences of six inches or more, consider it a non-level site.)

Plot Space Grid

Plot The Space

The site of your shed foundation will need to include about three feet of clearance beyond the outside perimeter of the shed's footprint, plus extra space for a ramp. The actual shed foundation should be plotted in the center of that space, and its dimensions should extend about a foot beyond the outside perimeter of your shed on each side.

Removed Soil within Plot Grid

Clear Turf and Soil

Within the boundaries of the shed foundation itself, turf and soil should be removed to a depth of at least four inches. That dug-out space should be square and level.

Gravel Pad within Plot Grid

Create a Gravel Pad

Crushed stone (1/2" to 3/4") should be used to fill the dug-out space, then leveled out and properly compacted to a gravel depth of at least four inches throughout. If more than four inches of fill are needed, it should be compacted in four-inch layers. When the gravel pad is finished, your shed floor joists can then rest directly on top of the gravel.

Even experienced DIYers may have questions or encounter challenges when building a shed foundation. Therefore LP strongly suggests consulting or hiring a qualified building professional. Your shed dealer may also be able to build a shed foundation for you.

Curved Plot Grid

Plot The Space

The site of your shed foundation will need to include about three feet of clearance beyond the outside perimeter of the shed's footprint, plus extra space for a ramp.

Timber Box surrounding Plot Grid

Build A Timber Box

Your timber box should be made of pressure-treated 4' x 4' lumber, and its inside dimensions should extend about a foot beyond the outside perimeter of the shed on each side. The top layer of lumber can be flush with the highest point of the site. All sides of the timber box should be made level and anchored to the ground with rebar. Any turf and loose soil should be removed from inside the timber box.

Gravel Pad after Timber Box

Create a Gravel Pad

Crushed stone (1/2" to 3/4") should be used to fill the dug-out space, then leveled out and properly compacted to a gravel depth of at least four inches throughout. If more than four inches of fill are needed, it should be compacted in four-inch layers. When the gravel pad is finished, your shed floor joists can then rest directly on top of the gravel.

Even experienced DIYers may have questions or encounter challenges when building a shed foundation. Therefore LP strongly suggests consulting or hiring a qualified building professional. Your shed dealer may also be able to build a shed foundation for you.

*This page does NOT include complete instructions for building any kind of shed foundation. LP strongly suggests that you consult or hire a qualified building professional to ensure proper construction. Many shed dealers also offer the option of having the shed foundation prepared for you. Whether you hire a professional or build a shed foundation yourself, you should first check with your local building inspector about any building codes that may apply and any permits you may need. Also remember to check the rules of your homeowners association, if applicable.

These general guidelines may not apply to your specific situation. Before starting to build a shed foundation, always check with your local building inspector about applicable building codes and required permits. If you live in a neighborhood with a homeowners association (H.O.A.), you should also consult the H.O.A. rules before beginning. Always take thorough safety precautions when building a shed foundation. Call your local utility company before you anchor support beams or begin digging into the ground. Avoid using tools or equipment you are not properly trained to operate. Do not attempt to build a shed foundation on sloping, moist or unstable ground. Louisiana-Pacific Corporation and the vendors involved in the creation of this website are not responsible for injuries, errors, property damage or dissatisfaction related to the process of building a shed foundation. It is the responsibility of the shed owner to ensure the shed foundation is built safely and properly by qualified individuals.