Ground Preparation For A Shed: 7 Mistakes To Avoid

A backyard shed is one of the best investments you can make to increase both the value and the usefulness of your property. But before it arrives at your property (or you build it) you obviously want to think about ground preparation for your shed!

Preparing the ground for a shed is not an incredibly complex job. Good tools, quality materials, and proper planning will make the job painless and efficient. However, there are some common mistakes you’ll want to avoid as you work on the project. If you’re planning to hire a site preparation contractor to install your shed base, you’ll also want to make sure that they’re qualified for the job and aware of these issues. Here are 7 mistakes not to make:

1. Placing Your Shed Too Close To Property Lines

While this is technically not part of the actual ground preparation for your shed, it’s important to double-check where your preferred shed location falls relative to your property lines. Most townships and municipalities have specific requirements for building setbacks (distance from property lines) and you’ll want to check them before you start building.

It’s common for local regulations to require a shed to be 5-15 feet from the rear or sides of your property. For instance, Manheim Township in Lancaster County, PA requires a minimum of 5 feet setback from the side/rear property lines.

It’s best to check directly with your local zoning office to see what, if any, requirements affect you.  If your property is part of a homeowners’ association, they may have additional requirements and if there are any easements on your property (such as overhead utility lines) you’ll want to take those into account as well. You can read more about choosing the ideal location for a shed here.

2. Preparing A Shed Site On Low-Lying Ground

If there’s anything you don’t want, it’s a flooded shed! If you have a choice, you will definitely want to avoid placing your shed in any swampy or low-lying areas of your property. Look for a high, well-drained spot and do the ground preparation for your shed there.

Building a shed in a wet area can have several negative effects, even if you can keep your shed from flooding. For one, excessive moisture will tend to make your shed deteriorate faster as it promotes rot. In addition, mold and mildew love to grow on buildings in wet areas. Finally, maneuvering any lawn equipment becomes much more difficult when the ground is soft.

level ground for shed swamp

3. Not Leveling The Ground Properly Beneath Your Shed

This is probably obvious, but it bears repeating. One of the quickest ways to cause issues in your shed is to simply put it in the backyard without first making sure the spot you’ve chosen is level!

If a shed is off-level, it can put strain on the structure which the framing was not designed for. Also, if the slope is too steep, anything with wheels will find a way to roll around in the shed! You can read more about how to level the ground for your shed here.

4. Using Only Concrete Blocks For Ground Prep Under Your Shed

There are a lot of people who will suggest placing your shed on concrete blocks, but in the long run this is probably not the best ground preparation for a shed.

shed on foundation blocks

One of the biggest reasons to not use concrete blocks under a shed is the fact that the shed will not be supported evenly. Even if you are able to perfectly level all the blocks (which is difficult) when you first place your shed, as the years go by, the blocks will tend to settle at different rates. This can put unnecessary strain on the shed’s framing, causing it to show its age much faster.

Eventually, you might end up with a shed that is listing to one side. Worse, the uneven strain on the shed’s frame can cause windows and doors to bind, preventing easy opening and closing.  

In addition, sheds on blocks offer a perfect place for critters to burrow. Once they’re underneath the shed, they’re much more likely to cause damage to the structure from below. We have an entire article about the use of concrete blocks under sheds here.

As an alternative to concrete blocks, a gravel foundation is one of the most economical and durable ways to prepare the ground for a shed. It will support the entire shed evenly, keep the bottom of your shed well drained, and discourage animals from nesting beneath your building. Here are three more pitfalls to avoid when using gravel for you shed base…

shed block foundation floor

5. Not Preparing Enough Extra Space Around Your Shed

If you’re preparing ground for a 10×12 shed, you’ll need a 10×12 foundation, right? Well, not exactly. It’s important to plan your foundation with some extra space around your shed.

gravel shed foundation

Generally speaking, your shed foundation should allow for at least 12” extra on each side of the building itself. So, if your shed will be 10×12, your gravel foundation should be 12×14.

Allowing 12” on all sides of your shed, accomplishes a couple of things:

First, it reduces rainwater dripping off the roof from splashing up against the sides of your shed. This will keep the sides of your shed cleaner and help them last longer.

Second, extra gravel will help keep grass and weeds from growing along the sides of your shed. Grass can trap moisture around the base of your building, helping it to deteriorate faster. Also, you run the risk of scratching and scuffing the sides of your shed as you trim the grass around it every week. You can read about choosing the correct size of shed foundation here.

6. Doing Ground Preparation For Your Shed Without Landscape Fabric

Gravel alone might not be enough to keep all the grass and weeds away from your shed. It’s a good idea to add landscape fabric as part of the ground prep for your shed. But what exactly is landscape fabric?

Landscape fabric (also known as weed barrier) is a fabric, generally made from polypropylene fibers that is placed under flower beds, gardens, and other landscaping to prevent unwanted plants from sprouting up through the soil.

By placing a fabric weed barrier over the soil before adding the gravel to your shed foundation, you almost completely eliminate the chances of any weeds sprouting up around your building. Additionally, the fabric helps separate the gravel from the soil beneath it, adding extra stability to the finished shed base. 

At Site Preparations LLC, we use commercial grade landscape fabric in every shed ground prep job we do.

level ground for shed weed barrier

Photo: The Spruce

The barrier product we use is actually the same type of heavy duty fabric used in road construction to prevent potholes! It adds a lot of stability and resilience to the gravel foundations we create and we won’t build a shed pad without it. 

7. Preparing Ground For A Shed Without Adding A Perimeter

A lot of landscapers or DIYers miss this important step in the shed site prep process. It might be tempting to just clear a spot of grass, lay down some weed barrier, spread a pile of gravel around, and call it good enough. Don’t forget the perimeter, though!

A solid wooden perimeter helps to contain the soil and gravel for your shed foundation, so it won’t be spread around and work its way into the lawn as the years go by. It’s especially important if you’re planning to build your shed on a spot that’s off-level. In that case, your perimeter can also double as a retaining wall.

Choose a high-quality, pressure-treated wood for this job. Make sure the lumber you select is rated GC (ground-contact) since it will be exposed to soil moisture for years to come. In addition to screwing the perimeter together, the corners of the lumber should be drilled through and staked down with rebar to keep it anchored to the ground. At Site Preparations LLC, we use 4x6s for most applications (6x6s under some circumstances). 

landscape timber installation for shed pad

Let’s Do It

And there you have it!  Plan ahead, avoid these mistakes, and you’ll be well on your to having a long-lasting shed foundation!

If the project seems a little bigger than something you want to tackle yourself, you always have the option of working with a professional site preparation contractor to do the ground preparation for your shed. Site Preparations LLC offers shed pads, garage foundations, and general site prep throughout Pennsylvania, New York, New Jersey, Delaware, Maryland and beyond. Give us details on your shed project and we’ll be glad to provide a free quote for ground prep!