Having a storage shed in your backyard can be a big bonus for storing your yard tools and lots of other stuff. And it all begins by preparing the ground so it’s fairly flat and level. You certainly don’t want to go thru all the trouble of building a storage shed and have it sink or rot. That’s why it’s important for proper ground preparation.
In this article I’m going to look at preparing ground for a storage shed in your backyard. I going to go over “can I put a shed on a gravel base?” “how to level a shed on uneven ground” and finish with “how high should a storage shed be off the ground.
Can I Put a Shed On a Gravel Base?
Yes you can put a pre-finished shed whether its resin, vinyl or metal. You can also use a gravel base for a shed foundation if you’re going to build the shed yourself. The first step is to find a location to put your shed. If you have already chosen the spot for your shed… Great!
If not and need some help you can read my article “Choosing the Best Location For an Outdoor Storage Shed?”. In this article I go over the use, permits and bylaws, property layout, size needed and access as well as design and appearance. And the bonus section how to draw a site plan. You can read the article here.
At this stage you should know what size of shed you’re going to be installing. If not I have another article “How do I Choose the Right Size Storage Shed?” in this article I go over the different factors that will affect the size of storage shed you can build. You’ll want to choose the right size the first time. You can read the article here.
What you need to do first is level the surface and remove any existing grass, roots, and top 4 to 6 inches of top soil. If the spot is not level you can scroll down to find the section that applies to you on how to deal with uneven ground.
If you’re using a shed that comes with a base you’re still going to want to level the area and get rid of any roots and other rubble in the spot. You still going to want to have a firm base to set the sheds foundation base onto and something to attach the shed to especially if it’s a metal or other lightweight material.
You’re also going to want to put a weed-proof material of the surface so you don’t have weeds and grass growing inside the shed. Don’t rush thru this step of preparing ground for your storage shed; the base is what’s going to provide you with years of trouble free service with your shed.
What Gravel Do I Use For A Shed Base?
When you’re making your gravel base for your shed foundation be sure that you use what’s known as crushed rock. Preferably ¾ inch crushed rock that will also have some finer crushed rocks as well. This mixture will be easy to compact and it will create a nice firm base to build on or to set-up your foundation kit on.
If you’re going to be building a storage shed that’s going to be used to park heavy equipment in then you will want to have a much stronger foundation and the concrete slab is the ideal choice. If it’s just going to be for a small shed kit made from metal or plastic then the crushed gravel will work fine.
I prefer to use the crushed gravel for the ground base and then use pressure treated 4x4s or 6x6s on top of the gravel and then add the treated wood floor joists and plywood. This makes an elevated base with excellent drainage and it’s also not permanent and if you decide later on that you want to move the shed it can be done. With the concrete base it’s not movable and way more expensive than using the crushed gravel.
Other Ways to Use Gravel For Ground Preparation
Always find out what requirements there are from your local building authority or building inspector before beginning any project. In addition to using a gravel pad for your backyard storage shed you can use a two foot strip of gravel and then use pressure treated material to make a pad to build the foundation on.
This is my favorite way to install a shed foundation. Just remove the top layer of grass from the site and then dig out the perimeter about 4 inches where the pressure treated material is going to sit, which would be the dimension of your storage shed. So if your shed is 8 foot by 12 foot you would dig a trench 4 inches by about 2 feet so the center of the trench is 8 foot by 12 foot.
This would leave about 10 to 11 inches of gravel past the pressure treated material and it would be at ground level. Now you’ll have your pressure treated base at the size of your shed, in this example it would be 8 foot by 12 foot to the outside of the base sitting on the 4 inch by 2 foot crushed packed gravel.
Pros and Cons of Gravel for Ground Preparation
– Can make a base for most sized storage sheds.
– The least expensive choice.
– Not permanent.
– Allows liquids to go thru.
– Keeps the shed floor near to the ground.
– May sink and compact more after set-up.
– Can cause moisture problems if not on high ground.
– Poor choice if there’s no floor in the shed.
I added a drawing this shows the plan view of an 8’- 0” x 12’- 0” storage shed base and I’m going to go over how to use gravel for your sheds base step-by-step. If your shed is not the same size as the example just use your size, the steps will be the same. You will need a fairly level spot for this gravel base to work.
Step 1] Locate where you want to put your storage shed.
Step 2] Using some red spray paint mark out on the ground the size of your shed. Remember to add extra for the 24 inches gravel base as it will extend past the actual shed size about 10 inches.
Step 3] Remove the grass and any other debris and top soil, about 4 inches deep.
Step 4] Add the crushed rock and tamp. You can use a piece of the 8 foot 4×4 to tamp the gravel down.
Step 5] Cut your 4×4 base to size and place on the gravel.
Step 6] Nail or screw the 4×4 base together.
Step 7] Rake out the center portion and put some black plastic or landscape fabric over the inside of the base. This will prevent grass and other stuff from growing.
Step 8] Measure and put the 4×4 base exactly where it needs to be.
Step 9] Check the base for level and you can tap the high spots into the gravel using a sledge hammer.
Step 10] Rake and soil from that you removed back around the outside even the rest of the ground.
There you go, now you have a level base to build the platform or floor for your shed.
How to Level a Shed on Uneven Ground
When preparing the ground for your storage shed it’s not as important that the ground is perfectly level, however you need to make the storage shed level. When the only location for your shed is on uneven ground you’ll need to make some changes to the sheds base.
This will depend on how much slope your spot has, the soil conditions and how well the area drains; as well the type of shed may affect the preparation. There are 4 steps to follow for dealing with sloping ground.
Step 1] The first thing is to find out how much slope your dealing with. Using some stakes place them where the outside corners of the shed will be. Using a string line attach it to one stake and then level the line all the way around the area, use nails in the stakes to position the line and a line level or other level to position the four points.
Now using a tape: measure the distance from the level line at the corners to determine the amount of slope you’re dealing with. You can string a line across the center to determine the slope in that area if it’s needed. You should now know how much of a slope the ground has and this will determine how to deal with it.
Step 2] If the slope is less than 2 or 3 inches you can dig down the high areas to make the shed base level. If the slope is over 3 inches than you’ll want to use some concrete blocks, try to use concrete blocks that are 4 inches thick.
By using a combination of concrete blocks and digging down the higher spots you can level out 3 to 8 inches of slope. It’s fine if the ground slopes this amount to use the concrete blocks. As your working use a straight 2×4 and a hand level to get the correct height for the shed base.
Step 3] If the slope is over 8 inches and more you’re going to have to use post and beam construction or concrete solo tubes, either one you’re going to need to use a post hole digger and dig down so there’s at least 4 feet of the solo tube or pressure treated post. You may be able to hire a bobcat with a post whole auger to drill out the holes.
Be sure to know ifs there’s any buried power lines, natural gas lines or water and sewer lines in the area you’re going to be drilling holes into. Make sure you call the proper authorities and get clearance before going ahead with the build.
I’ve added a drawing below showing the side elevation for using pressure treated 4x4s or 6x6s depending on the size of the storage shed. It will be designed for an 8 x 12 shed, however you can use your size the base will be the same installation for any size shed base on sloping ground. I will do step-by-step instructions for you to follow.
Step 1] Locate where you want to put your storage shed.
Step 2] Using some red spray paint mark spay an x on the ground where the pressure treated posts will be going. If you’re using 4×4 posts make the holes at least 8 inches in size and for 6×6 posts make the holes at least 10 inches in size.
Step 3] With a post hole digger or using a gas powered auger dig the holes, where I live in Northern British Columbia code requires 4 feet below finished ground level to be below frost line. Your area may be different, check with your building inspector. Either way you want at least 4 feet of the post in the ground to stabilize the structure.
Depending on the size of your storage shed you don’t want to span any more than 8 feet. So if it’s over 8 feet add another post in the center as I did on the 12 foot side.
Make sure you have the entrance door of your shed at the end where it’s at ground level; you don’t want to have to build stairs or a ramp to go in and out of your shed. If you’re building your own shed you should have the plan before you build the base. If you need a plan I recommend you check out “Ryan’s Sheds Plans”. You can see all the plans here.
Step 4] When installing the posts make sure that you leave enough of the post out of the ground so you can level them off from the highest point of ground level. Add a bit of gravel into the bottom of the posts when you have them set where you want them.
Using some stakes string an offset line to measure from to make sure the posts are in the correct place. Having the hole dug bigger allows for some movement when setting them. Use bracing if needed to hold the post in place.
Step 5] Using the 55 pound bags of pre mixed concrete, mix 3 bags and add too each hole around the post, use a thin stick or broom handle to tamp the concrete into holes.
Step 6] Wait at least 24 holes for the concrete to set, and then fill in the top of the holes with fill and tamp.
Step 7] Carefully remove the bracing and cut the post that’s closest to ground level and then using a straight 2×4 and a 2 foot or 4 foot hand level, go around and mark the other posts to the same height and then cut them all off.
Step 8] Install the treated 4x4s onto the cut off posts and nail or screw them together.
Now you have a level base to build your sheds floor onto.
How High Should a Storage Shed Be Off the Ground?
When preparing the ground for your backyard storage shed you need to take into consideration how far off the ground it will be. How long your shed will last depends on how good the base and foundation is. If it’s siting on the ground it can rot or be subject to water damage.
I’ve seen many storage shed sink into the ground and rot away. To avoid this and get years of service begin your installation with good preparation. I like to recommend that sheds around 120 square feet be built on a treated wood base and pressure treated ties or skids. This will give you at least 4 inches of space under your shed floor for air movement and also keeps it out of any water that may be present.
If you’re going to be using a shed or building one that’s over 120 square feet you’re going to want to use a more permanent foundation. I just designed a shed for a local church and it was 19 feet by 12 feet. It has3 pressure treated 6×6 beams with treated 2×6 floor joists so it’s going to be around for years.
No matter what kind of shed you’re going to be buying or building you need a good strong base for it. Those floor kits that come with some resin and metal sheds are for flat ground and it should have a solid base at least 4 inches to keep the shed from sitting on the ground. Another advantage of a solid base is you can easily secure the sheds walls to your base and you won’t have to worry about wind blowing your shed away.
I hope you have found this article helpful. If your situation is different and need some advice on preparing the ground and building the base you can leave a comment and I’ll do my best to answer your question. Thanks for reading.