If you’re preparing to have your shed installed, you’re probably wondering whether you need a foundation for a shed and, if so, what kind of foundation is best for your shed. We’ve already outlined our preferred shed foundation in this article and given an overview of all shed foundation options here. Now we’ll look at a shed foundation type that we don’t recommend: shed foundation blocks.
Installing and leveling your shed on cinder blocks might seem like the easiest solution for shed site preparation. After all, there’s little preparation required if your site is already fairly level. All you need to do is make sure the installer has access to a stack of inexpensive cinder blocks. (Note: leveling the ground for a shed is a better solution)
The problem with using cinder blocks is that it can create problems with your storage building down the road. This is especially true for larger sheds. We’ll now look at the potential problems and reasons not to use shed foundation blocks.
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A Shed on Blocks Might Settle Over Time
Installing a shed on blocks might seem like an easy solution but it can cause problems down the road.
One problem is that your shed might begin to settle over time. This is especially true if the ground is soft and unstable.
In the north, the freeze and thaw cycle can be another cause for slight movements that can cause a shed on blocks to settle over time.
The Doors Might Not Open and Close Properly
A shed that’s not level doesn’t look good and it doesn’t feel good when you step inside. Another potential problem caused by a block foundation is doors that don’t open and close properly.
When a shed settles, it can cause the doors to come out of alignment. This can result in either the doors rubbing the top when your open and close them or not latching properly. You can usually correct this by lifting one corner of the shed until the doors line up again, but that’s not something you want to mess with very often. The best solution is to do it right from the start and place your shed on a solid gravel or concrete foundation.
The Center of the Floor May Not Be Supported
If you choose to install your shed on blocks, there’s a good chance your installer will not take the time to place blocks under the center. That’s because it’s a difficult and time consuming task.
Not having the center of the floor adequately supported can result in a “bouncy” floor that sags over time. This is especially true if you’re getting a larger shed such as a garage that will be storing heavy equipment and vehicles.
The best antidote to a sagging floor is to have your shed installed on a level gravel pad which will have continuous support under the entire floor. You’ll never need to worry about a weak floor with a proper foundation.
Foundation Blocks Do Not Block Grass and Weeds
Grass and weeds growing against the sides of your shed can be a problem because it does not allow the bottom of your shed to dry out after rain. This can cause premature rot and supports the growth of mold and mildew.
It also increases the chances that your shed will become scuffed and bruised when you mow and weed whack around your shed.
Foundation Blocks Do Not Keep Your Shed Clean
If your shed is surrounded by dirt there’s a good chance that the dirt will splash up against the sides of your shed when it rains. The best way to prevent this is with a gravel pad that’s wider than your shed. Learn more about the benefits of a gravel pad that’s 12″ wider than your shed all the way around.
Foundation Blocks Allow Critters to Move In
If you choose to install your shed on blocks there’s a good chance that you’ll be dealing with unwanted critters at some point down the road. Foundation blocks provide no protection against these types of annoyances.
Although a gravel foundation does not guarantee that you won’t need to deal with this, it will certainly discourage critters from taking up residence under your shed.
Many Builders Discourage the Use of Blocks
Especially in the Northeastern part of the United States, many shed builders discourage their customers from using blocks for several reasons. Installing a shed on blocks often takes more time and it might result in more damage to the shed as discussed in the previous points. Installing a shed on blocks may void the manufacturers warranty. If you’re not sure, check with your builder to find out what foundation they recommend.
The fact is, using blocks under your shed is just one of a number of mistakes to avoid when doing ground preparation for your shed. Check out the rest of our articles for more site prep tips and how-to advice.
What is the Best Shed Foundation?
A Gravel Shed Pad
In most cases, a gravel shed pad is the ideal foundation for a storage shed (also an ideal base for an above-ground pool). It eliminates or reduces the severity of all of the problems discussed above and can increase the life of your shed. It also reduces maintenance issues that might come up in the long run. A gravel shed pad is great for sheds of any size, from a tiny garden tool shed to a gigantic two car garage. Gravel shed foundations are also the easiest kind to install; if you have building experience, you could potentially calculate how much gravel you need and build it yourself. The only requirement is that the shed you’re getting have a wood floor. If you decide to build it yourself, check out our complete guide on how to install a gravel shed pad.
Good afternoon. I was just notified that my shed is on the ground. I been in my house for 10 years and I need some advice on how to get my shed off the ground without being to expensive. I have a small shed 8×8 and I don’t want it to cause problems down the road. What would you suggest and are there anyone you know can help me?
Hi Perlean, if you’re in the Mid-Atlantic US, give us a few more details about your situation through our Contact page and we’ll see if it’s something we can help with!
I have a 14ft x 20ft better built barn tyoe shed im using as a tiny home atm and it on cinder blocks pillars like they laid two blocks then rotated the next two blocks 90% and so on. they are like 3 or 4 coarses high on one ends and maybe on on other end what would u recommend for me too do bc i know one corner has settled about 2 to 4 inches
Hi Ethan, it’s always more difficult after the building is in place! If you have space next to where the building is now, you could consider installing a gravel foundation as we explain in this article. Once installed, it may be easiest to hire a professional shed mover to transfer the building over.
I need to build a shed on a slop and I want to use piers to gain the knowledge for another project down the road. Is a gravel box that much better than a pier installation?
Hi Bernard, piers are a good option if you’re in a frost-prone area. Gravel pads allow water to drain away, while still keeping critters and weeds from under your building. In fact, you can combine the two foundation types as we did in this job:https://new.siteprep.com/recent-projects/new-jersey/matt-d-gravel-shed-foundation-in-mt-ephraim-nj/
We have a tutorial on installing gravel shed foundations here: https://new.siteprep.com/how-to-install-a-gravel-shed-foundation/
If you’re in the Mid-Atlantic US, you can get a quote on professional installation here: https://new.siteprep.com/get-quote/
I need to determine what type of foundation would be best for my situation. I’m getting a 15’x8′ plastic she’d. My understanding is that the floor is also plastic. The area where I want my shed is on a slope. Please walk to through the best foundation choice for my situation. Thank you
Hi Shari, we’d recommend a gravel shed foundation with a treated lumber perimeter, as highlighted on this page: https://new.siteprep.com/gravel-stone-pad/
We have a guide to whether your shed needs a foundation here: https://new.siteprep.com/do-you-need-a-foundation-for-a-shed/
We have a guide to building your own shed foundation here: https://new.siteprep.com/how-to-install-a-gravel-shed-foundation/
You can see more example shed foundations, including some on hillsides here: https://new.siteprep.com/recent-projects/
Hope that’s helpful!
I have a 15×8 plastic shed. My yard is on a slope, so one option was considering a cinder block foundation with gravel inside. What is your opinion?
Hi Jacob, that type of foundation might be an option, but we recommend a shed foundation of crushed stone inside a treated lumber perimeter, as detailed in this how-to article.
I moved into a house with what looks like a concrete foundation in the back. It is an old house (1910) and we can’t figure out what the the concrete patch is. My guess is that it was once an off-street parking place for the property or some type of patio. How can I tell if this would be a good foundation for an 8×12 skid foundation shed?
Hi Daniel, if it’s a full concrete slab, it will most likely support a prefab shed. Two things to keep in mind:
1. Is it level?
2. Will it drain well? (It’s not ideal to have water pooling around the bottom of your shed if you can help it.)
Hope that helps!
I have a 10’ x 20’ shed built on a slope. It was built on wooden blocks and now the shed, after 20 or so years, has settled on the lower end. Would you recommend tearing up the wooden floor to get access to the frame and lifting and levelling the lower end?
Hi Cherise,
By wooden blocks, we assume you’re talking about the wooden runners that support the floor joists of the shed. If that’s the case, it may be easiest to make the repairs from the outside, as you will probably need to lift the lower corner of the shed with a jack or something similar, then add support underneath it. Alternatively, you may be able to have a shed moving company lift the shed off its foundation, install a proper foundation (like a gravel shed foundation), and move the shed back. You may still need to remove parts of the shed floor if the shed runners or joists need repair.
Hope those ideas are helpful!
Got a great deal on a plastic shed 8 x 20. No floor. Slight slope, but at the base of a hill with considerable water run off. Currently houses a 20 year old 8 x 12 that is rotten.what is the most cost effective way for foundation without sacrificing sturdiness and security.
Hi Michelle,
We recommend a compacted gravel shed foundation, which will support the shed while still allowing excess water to drain away. You can learn more about our gravel shed foundations here or see how to build one yourself here.
I live in Eugene Oregon where it does frost sometimes but we don’t get snow very often and it usually doesn’t stay long. I have an 8x10ft metal shed that has a wood floor. I am going to do a gravel base but I don’t know if I should also use concrete blocks because it can frost here or if I don’t need to since it is not for long amounts of time like Minnesota or something. I would rather not since it makes sense that the gravel supports the weight more evenly and not wanting animals to make their homes under it (nothing against animals) but I am worried about the moisture mildew through the wood floor without air flow underneath and damage from the occasional frost. What do you think concrete blocks on top of gravel or no concrete blocks? thanks
Hi Jamie,
We’ve installed 1000s of these foundations throughout the Northeast US, where we get plenty of frost, and we have not found that to be an issue. We don’t know the exact design of your shed floor structure, but our opinion is that the stress on the building structure (from spanning between concrete blocks) will outway the danger of any moisture concerns. One of the main benefits of a gravel foundation is that it will let moisture drain away from the bottom of the shed more quickly (compared to concrete). Hopefully that makes sense!
Hi, will there be any issues with a woven fabric properly draining water under the compacted gravel? I installed one yesterday following the youtube video and plan to start building the shed soon. My soil is sandy and drains very well. Thanks for any advice.
Hi Steven,
We haven’t found any drainage issues using stabilization fabric. It is permeable enough for water to pass straight through and into the ground.
I am looking to buy a shed that has a galvanized steel foundation. I told them I’m looking to get quotes on a gravel pad with at least one foot around the shed and that I’d like to place the shed directly on the gravel. The galvanized steel does have holes punch into it for air flow and this would be placed in my yard in an area that doesn’t get as much snow or rain as does other areas. In the northeast we’ve seen a lot of rain and snow this year and the area still is drier compared to other parts of my property. The company (sales and corp) still insists that some cinder blocks should be used for airflow. Do you think they are just accustomed to people placing them without gravel and that’s why? What would you recommend? Based on the article it sounds like cinder blocks aren’t a great idea and I’ve seen sheds on gravel pads with and without the blocks so wondering what is the best thing to do to keep the shed in great shape. Thank you.
Hi Josh,
In our experience, the shed industry at large is moving more and more toward gravel pad foundations. Granted, most of the companies we work with are building wooden sheds, with pressure-treated wooden runners. The design of these sheds does give some airflow between the runners.
One other consideration would be whether the shed manufacturer has a warranty that would be voided if you don’t put it on the foundation they choose. So while we can’t definitely speak to galvanized steel sheds, our preference would still be to put it on a gravel pad. Hope that helps a little!
I have a 20 x 20 area which formally housed a Play set
It has pea gravel
I am looking to put a 12 x 12
Shed there now thought of removing some gravel and
Placing it on cement blocks
Any ideas would be appreciated
Here’s an article that might help you out a bit more: https://new.siteprep.com/ground-preparation-for-a-shed/
I will be getting a 10×20 she’d delivered in the next week or two. I was planning on just putting concrete block or leveling blocks ( that came out from underneath our 1880’s house when foundation work was done). Is this a good idea or not? We live in Central MS
Because of the different reasons mentioned in the article, e.g. lack of support, door issues, etc., we recommend an actually shed foundation, especially for the size of shed that you’re ordering.
We’re considering a large portable shed (14’x40′ with floor) as an alternative to a pole barn in Illinois. The pole barn builders in our area have a much longer lead time. The structure will be permanent on some farm ground we own for weekend stays. I’ve done several pole barns (concrete floors poured after shell is up) but I’m new to portable buildings. My question is, I have water and electric available within 100′ of the building site. If I prep a gravel pad, how do I pull my utilities into the building. With pole barns, I always stub them out before the concrete is poured. I can’t do that if they are going to slide a building onto the pad. Any ideas would be appreciated. Thanks!
Hi Eric, we may need some more information in order to better assist you. Please feel free to reach out to us anytime, so we can discuss the work in more detail. Thank you. https://new.siteprep.com/get-quote/