So, you’ve committed to building that shed, or maybe you’ve ordered a pre-built shed to be delivered to your property. You’ve decided on the shed you want. Now you just need to figure out where in your yard to put it. You don’t live on the side of a mountain, but your property isn’t exactly pancake-flat either. You’re going to need to create a level surface for that shed.
So, how do prep your shed base, and is it something you can do yourself? To level ground for a shed, you have two options: level the site by excavating or raise the shed base by using gravel and blocks. In this article, we’ll discuss how to complete both options.
How to Level Ground for a Shed
This is a project that can be completed by most DIYers with a minimal amount of tools and cost, so don’t be intimidated into hiring a pro to accomplish this task.
Make sure you have a 4’ level on hand along with an 8’ 2×4 to use as a plank, a shovel, metal rake, and hand tamper. You’ll also need wooden grade stakes, a mallet, and a string line.
Step 1: Planning and Preparation
When considering the following, keep in mind that your shed isn’t just the dimensions of the shed itself. Your shed’s overall footprint is about 25% larger than the actual shed to account for proper spacing between other structures and your property line.
Choosing a Location
There are a whole host of things to think about when deciding where to place your shed. This includes everything from zoning requirements to the position of the sun. First and foremost, check zoning requirements, building codes, and HOA rules.
There’s nothing worse than completing any kind of project only to find out later that you’ve violated a building code or your Homeowner’s Associations covenants. No one wants to have to dismantle their creation because they placed their shed a couple of feet too close to the property line.
Drainage is also a consideration. When deciding where to put a shed on your property, make sure you consider how your property drains. Placing your shed in a low area that tends to collect rain runoff can lead to water damage and mold.
Other factors to think about include accessibility, slope, aesthetics, and sun exposure. Do you want to be able back a car up to the shed? Will you need to build a retaining wall? How should you position your shed, so it doesn’t visually detract from your property? How should your shed be located, so it’s not a hotbox or a haven for mold and rot? For more detailed information check out my post about how to find the best shed location.
Step 2: Staking and Squaring the Site
Once you’ve chosen a location, it’s time to begin staking it out. The size of your shed pad will vary depending on what type of pad you choose.
If you plan on creating a gravel pad for your shed foundation, then it should be 1’-2’ larger than the shed itself to account for a proper buffer. Make sure to consider this when staking out the site. For example, the size of a gravel shed base for a 10’x12’ shed would be 11’x13’.
If you’re planning on using a concrete pad, blocks, or piers, then you should not use a buffer. The dimensions of the pad should match the shed size.
Begin by locating the first corner and pounding in stake number one. For proper measurements, it’s essential that this stake is pounded in straight. Use a level to help you accomplish this task if needed. A stake that is installed at an angle will throw off your measurements when you go to square the site.
Next, pound the second stake in 4’ from the next stake as you move toward your second corner, again making sure the stake is perfectly straight.
After staking your second corner, you’ll need to stake the third one. This is probably the most difficult part of this process, but it’s also the most critical to create a square shed foundation. After pounding in your second stake, measure 3’ from the first stake.
Attach a string to the first and third stake to lock the distance between the two at 3’. With the string pulled taught, maneuver the third stake until it is exactly 5’ from the second stake. Then pound it into the ground. Now you’ve ensured that the angle you’ve created at the intersection of the first and second stake is 90 degrees.
This process, commonly known as the 3,4,5 method, uses a basic geometry principle for creating a triangle with a right angle. You now have a shape that you can use to square the rest of your shed foundation.
Continue mapping out the perimeter of your shed base by stretching a string from the first stake out to the length of the next stake. Make sure the string touches the second stake slightly. In the case of a 11’x13’ shed foundation, you would extend the line 11’, and drive in another stake.
Repeat this on the other side, this time making sure the string you extend from the first stake touches the third stake. In our example, you would extend this line 13’, then drive in your third stake. From here, you should be able to extend a line 11’ from one corner and 13’ from the other corner to find the location for your fourth and final stake.
Next, wrap a line tightly around all four stakes. Again, make sure that your stakes are firmly in the ground to prevent them from being moved during this step. Lastly, use spray paint to mark the footprint of your shed base. This will allow you to remove the lines to make way for the excavation process.
Step 3: Option 1 – Excavation
If you opt for leveling the ground by excavating, then it’s time to begin digging. But before you do, make sure to consider what is under the ground. Any time you are digging into your yard, it’s essential that you know exactly where your utility lines are.
Don’t make an educated guess. Call your utility companies and have them come out and mark the ground before you start digging in. Once that’s done, start by removing all of the topsoil for the entire area that you’ve marked out, including the areas that don’t need to be excavated.
This ensures an even base free of debris and plant growth. It also makes for a more stable base. Why? Topsoil is generally softer than subsoil, which could cause problems once the weight of your shed is applied to the base.
How deep should you go when digging? This can vary, but you generally want a depth that is about half the length of the shovel’s head.
You can also tell by the soil color. Subsoil typically has a lighter color than topsoil. You can stop digging when you’ve reached this lighter color soil.
TIP: As any of us who have ever purchased topsoil for a landscaping or gardening project know, good topsoil is expensive. This is because it includes compost that plants use for nutrients. With that in mind, don’t just dispose of that black gold you’ve just dug up. Find another use for it on your property. Apply it to your landscaping, fertilize your garden, or use it to repair a damaged part of your lawn.
Once you’ve removed the topsoil, eyeball, which part of the area looks higher than the other and begin removing the subsoil. Remember, the idea here is to create a level surface, so remove the soil as evenly as you can without leaving a lot of inconsistencies.
Now that you’ve completed the soil removal, it’s time to get out that 2×4 plank and see if it’s level or not. Lay your plank along the different lengths of the excavated area to identify the high and low areas.
Move the subsoil until the plank rests evenly. Then place the level on the top to determine if the ground is even. Make sure to move the plank throughout the area to ensure that the entire plot is even adding or removing soil where needed. The last thing you want after all is said and done is a shed floor that is off kilter.
Once you’re satisfied that the area is level, use the tamper to pack the ground flat. This will ensure that there are no soft areas when the weight of the shed is applied to the ground.
Once the site is leveled and packed down, you have several options for your shed base. You can create a gravel pad by filling the area with a 4-5” of pea gravel. If you choose this method, you will need to Smooth it out evenly using your 2×4 plank and level to even the surface out.
For this type of gravel base, you’ll need to invest in a significant amount of pea gravel, which runs about $3.50 for a 0.5 cubic-foot bag at Home Depot. You may be able to find it cheaper if you purchase it in bulk.
Another option is to have the pros come in and build a concrete pad, although be prepared to spend significantly more on this.
Option 2 – Blocks and gravel
Not up for all that back-breaking digging, grading, and leveling? Maybe blocks are a better option for you.
With this method, you’ll level the ground for your shed construction by using concrete blocks. Begin by marking and squaring the site as in step one of this guide with one exception.
Unlike the graded area, which is larger than the actual shed, your concrete blocks will need to line up with the shed’s actual dimensions. Therefore, you should use the shed’s actual dimensions when staking the corners if you are using this method.
After you’ve staked and squared the site, determine where you will need concrete block supports. You’ll need supports at the corners and at intervals no greater than 4’ around the shed perimeter to have adequate support.
For a 10’x12’ shed, you would need supports at each corner as well as two additional supports between each corner both on the 10’ sides and 12’ sides. While this means smaller intervals on the 10’ sides, it is always better to go less than 4’ than to try and stretch beyond 4’.
The total number of blocks you will need is determined not only by the size of your shed but also by the steepness of the gradient you are trying to correct. A steeper grade will require more blocks on the low side to achieve a level base.
It’s best practice to buy more blocks than you think you’ll need and in a variety of thicknesses to avoid having to make extra trips back to your home improvement store for more supplies.
Which blocks should you purchase? Make sure you use only solid concrete blocks for this job. Using smaller blocks or hollow cinder blocks isn’t a good idea as they could crack and crumble over time.
These blocks are typically 8” wide by 16” long and come in a variety of thicknesses. I suggest buying the blocks in both 4” and 2” thicknesses. Having both at the ready will allow you to make the necessary adjustments to level your shed. Solid concrete blocks cost about $2 per block at Home Depot.
Begin by preparing the site. Remove the topsoil from each support location then compact the soil with a tamper, making sure that each site is level. This will ensure a secure base for each block support. Don’t skip this step. Remember, you want that shed floor to stay level for a long time.
Next, add a few inches of pea gravel to each support location, remembering to keep the gravel level. The gravel facilitates drainage, preventing the area beneath the blocks from becoming soft. Without proper drainage, the ground around the blocks can erode, allowing the shed to shift or sink.
Once the ground has been prepped, begin placing the blocks. Start on the high side, adding one block to each support location. Next, begin bringing up the low side by stacking blocks.
You may need to add two or three 4” blocks to the low side of the base to bring it up to the same height as the high side. Use the thinner 2” blocks during the leveling process to align all sides. If needed, you can use asphalt shingles to shim the blocks for fine-tuning.
To check that your supports are level, rest a 2×4 from one block support to another block support. Place a level on top of the 2×4 to check that the beam is level. Continue this process from support to support, making adjustments as needed until the base is level.
In cases in which you need to level an area with a steep gradient, typically when one side is more than 8” higher or lower than the other side, you may need to build a retaining wall to prevent the slope that you’ve cut into from eventually eroding into your shed.
If possible, avoid this extra project by choosing a location that doesn’t have a significant grade to contend with.
Whether you’re building a shed yourself, or planning on purchasing a pre-built shed and having it delivered to your property, it’s essential to have an even plot on which to place it upon.
Many of us don’t have a naturally flat back yard. But by following the instructions in this guide, you can create a level site for your shed, ensuring that it will have a solid base to rest upon for many years to come.