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How to Build a Shed Foundation on Uneven Ground

Lands are naturally not flattened and leveled. In fact, uneven grounds are common issues builders face. Good thing there are a lot of ways to build a structure even on steep grounds.

How to Build a Shed Foundation on Uneven Ground

Building a shed foundation on uneven ground will require you to assess and consider a lot of factors  From how steep the ground to the purpose of the shed, all of these will significantly affect how you must build the structure’s base as some shed foundations work better on certain settings while others do not. 

Wondering which shed foundation is the most appropriate for your shed?

This article covers a complete breakdown on how to build a shed foundation on uneven ground. 

Things to Consider When Building a Shed Foundation on Uneven Ground

While building a shed on uneven ground is attainable, there are still a few important aspects that homeowners like you must examine. These factors will also determine—and most likely dictate—what type of shed foundation you will have to use to level the structure flawlessly. 

That said, below are a few things you need to consider when building a shed on uneven ground.

  • The steepness of the ground. Grounds have natural uneven steepness. Some have a high slope, while others have a gradual slope only. Such a factor could inherently affect the way you need to plan the structure of your shed, as well as the amount of labor you need to expend.

    Uneven ground with a gradual slope, for example, is much more convenient to level compared to one with a high slope. It is because the latter normally requires post holes or sonotubes—which means you need to do some digging—while the former can be refilled with gravel and add a retaining wall only.
  • The door’s location. Accessibility is crucial when building houses and other structures. As such, you must plan where you will build the door first. As much as possible, place it somewhere where the ground is level—or at least with a low slope only. It would not only make the shed accessible but would also help avoid accidents.
  • The shed’s purpose. How you will use your shed will largely affect how you would build the structure. Things like the type of foundation you need to use for the structure and even the location are dependent on how you will use the shed.
  • The area’s building regulations. Lastly, check if your local area has building regulations you need to follow. A building permit, for instance, might be needed before you start the construction, especially if you plan on building a large shack.

Best Shed Foundation Ideas for Uneven Ground

Today, there are more than ten shed foundation options that contractors use to build an outhouse. However, not all are suitable to apply when building sheds on uneven grounds. 

To help you, here are the top four foundations that work well on asymmetrical grounds.

Gravel Pad Foundation

As its name suggests, a gravel pad is a foundation made mainly using gravel. It is the most straightforward and affordable type of shed foundation contractors use today. It works well on both flat and uneven ground too.

Gravel shed foundation comes in two forms: a gravel pad in a box and a gravel pad with a retainer. Here’s how they vary.

  • Gravel pad in a box. The shed base is essentially a bed of gravel enclosed within a box of wood. Each corner of the box is fastened using galvanized brackets while the lumbers are usually pressure-treated. The wooden box is an important element as it serves as the gravel container and solidifies the foundation further.

    Such a type of foundation is best for building shacks on uneven ground, specifically one with a slight slope.
  • Gravel pad with retaining wall. This type of shed foundation has the same design as the gravel pad in a box except it has a retaining wall. The retainer or retaining wall is added on one side of the box which makes the foundation firmer. It is made of pressure-treated planks or concrete blocks too. Gravel pad with retaining wall performs well in sheds that are built on uneven ground with moderate slope. 

Wooden Base Foundation


A timber base shed foundation, also known as portabase, is a type of foundation built mainly using wood. The frame is made of pressure-treated planks. It comes with metal spikes as well that are hammered down into the ground, which act as posts to keep the base in place and sturdy. It keeps the frame off the ground too and helps avoid rotting.

Moreover, the foundation can be installed in two ways also. You can place the wooden frame onto a patio, or you can simply lay it on a level or unlevel lawn. A wooden base shed foundation is best to use on grounds with high slopes and is very uneven. 

Plastic Shed Foundation


A plastic shed foundation is a modern base structure and design. The frame is built using plastic tiles or grids—that is 100 per cent made of recycled plastic—to form a base. The plastic tiles are then combined by clipping or locking them together, which makes the foundation the most convenient shed base to install. And, because it is made of plastic, it is guaranteed to be long-lasting, durable, and less likely to rot. The tiles are self-ventilating and free-draining. 

A plastic shed foundation is great to use on uneven grounds. However, it is also recommended to even out the ground first as much as possible to avoid floor issues in the future. 

Concrete Blocks Foundation


Next to the gravel pad, a shed foundation that is built using concrete blocks is the second most suitable base solution when building a shack on grounds with a slope. In fact, it is specifically recommended on grounds with an extremely steep slope. It is affordable to build, customizable, and available in several sizes and shapes. It is easy to stack them as well on uneven ground. 

Building a Shed Foundation on Uneven Ground

In building a shed on uneven ground, it is best to use a concrete block foundation. Although it may not be the best for some, considering the factors that I discussed in the earlier sections. Whichever base you want to use, the initial steps are all the same—and I will guide you. 

With that being said, you will need the following tools:

  • Tape measure
  • Pegs and string
  • Spade and shovel
  • Rubber mallet or hammer
  • Nails
  • Spirit level

1. Clean the Area

Before anything else, you must clean the area first. This includes weeds, shrubs, and other obstructions you can find in the area. Removing vegetation can help avoid moisture from seeping into the base and the shed’s floor. 

2. Measure and Mark

Once done, start measuring and marking the area. You can use a measuring tape or a string. If available, you can place wooden posts (or even bamboo canes) to enclose the area.

3. Level the Ground

Next, start to even out the ground. Use a shovel to dig, flatten, and level uneven areas. You can also use planks to even out parts with steep slopes by laying them across. 

4. Cover the Area with a Weed Membrane

Weeds are common issues that depreciate the quality of a shed foundation. To avoid such an issue, it is highly recommended to place a weed membrane on the area as they help stop weeds from growing and spreading around the shed’s base. You can place one or two layers of the material. 

5. Build the Base

Lastly, start constructing the base. There are several shed foundations you can use specifically for uneven grounds. Whichever foundation you prefer, make sure that it is sturdy enough to hold the shed.

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