Many of our clients come to us wondering, “Do you need a foundation for shed?” Once that question is answered, though, a follow-up question is often “What’s the best base to put under a shed: gravel or concrete?”
In most cases:
- Gravel is the best shed foundation, especially for portable buildings that come with a wood floor.
- Concrete is the ideal foundation for a garage or a shed without a pre-built floor.
Let’s talk about the respective benefits of each.
Table of Contents
Gravel is generally better than concrete for a shed foundation
As mentioned above, out of all the available shed foundations, gravel foundations are our choice for prefab sheds that come with wooden floors pre-built. If that’s the type of shed you’re planning to build/buy, the following reasons explain the benefits of a gravel shed foundation.
Better drainage = less rot and decay. A gravel base acts like a sponge by wicking away the water that would normally collect around the bottom of the shed. A concrete base, on the other hand, cannot absorb water. This can create more water runoff issues during heavy rain falls. Additionally, the bottom of the shed also won’t dry out as quickly with concrete.
Less water splashing against your shed. A gravel base functions like a diffuser when water that runs off the roof reaches the ground. The rough, porous surface of the gravel prevents water from splashing up. Instead, the water quickly soaks into the ground. With a concrete base, water from the roof will splash up against the sides of the shed. This increases the likelihood that any wood (including siding) on your shed will rot over time.
Cheaper than concrete. A gravel base has a price point significantly lower than concrete. If your building doesn’t require a concrete foundation, a gravel pad can save you hard earned dollars and allow you to invest more in things like landscaping (or a bigger shed!). We have an entire article devoted to shed site prep costs when installing gravel foundations.
Easier to install and remove. With a gravel base, you won’t have the heavy concrete truck driving on your lawn. A gravel base for an average sized backyard shed can usually be installed in a day or less. You may even decide to level the ground for your shed, calculate how much gravel you need, and build your own gravel shed foundation. And if you ever decide to move the shed to a new location in your yard or get rid of it altogether, a gravel base will be much easier to remove.
Concrete is generally better than gravel for a garage foundation
If your shed will serve as a garage (especially a multiple-car garage), it’s important to have a foundation that will properly support heavy vehicles. This is also true for sheds that are built or assembled on-site. The following reasons explain the benefits of a concrete garage or shed foundation.
Local regulations may require concrete. Some municipalities require certain building types or building sizes to be constructed with a concrete foundation or footers. This is especially true in areas that are prone to frost heave. Check your local code, as there are several types of concrete foundations (with varying costs) that may meet requirements. (For information on garage permits in PA, click here.) If you’re only installing a shed, concrete foundation piers at each corner, combined with a gravel foundation, may be satisfactory.
Concrete offers the best support for vehicles. As mentioned above, concrete is the best option for a garage. Years of driving a vehicle in and out can cause a building on gravel to start to shift. Concrete eliminates that danger. For both attached and detached garages built on-site, construction will usually start with concrete wall footers and a concrete floor. You can see several types of concrete garage foundations here and a complete guide to shed footings here.
Concrete resists settling. Concrete acts as a shield against environmental challenges that could impact its stability and structure. In colder climates, where freeze-thaw cycles are a common concern, concrete demonstrates remarkable resistance to settling. Unlike some materials that may have huge temperature fluctuations, concrete maintains its structural integrity, preventing the occurrence of cracks.
So, what’s the best foundation for a shed?
It depends…
A concrete shed base may be better and stronger than crushed stone in some situations.
But the truth is, the extra cost of concrete does not necessarily make it a better foundation for a shed. A gravel base is an ideal foundation for small prefab sheds and can even be a good option for some portable garages. However, concrete is a great option for larger garages and any building that’s not pre-built with a floor. If it doesn’t have a floor, then a concrete foundation is a good option.
Does That Help?
We hope that answers your questions! Please contact Site Prep if you have any additional questions. We’d be happy to give you a free quote on a shed or garage foundation. Or, feel free to read another article we’ve written about how to build a shed base on uneven ground.
You can also feel free to browse our galleries of gravel shed foundation photos and concrete garage foundation photos.
Hi there! I’m getting a 14×14′ finished shed built as a backyard office in Austin, TX. The builder generally builds on 4×4 pressure-treated skids (on concrete blocks, I think). Do you think that will suffice? Thanks!
Hi Aditya, building a shed on skids is pretty standard. The main concern would be placing the finished shed on concrete blocks. It’s a pretty common foundation style, especially in the southern US…The problem is that the blocks can tend to settle unevenly, putting extra strain on the frame of your building. You probably won’t notice it in the short term; it’s more an issue of longevity. We usually recommend a gravel foundation with a treated wood border.
We actually have an entire article dedicated to that question here: https://new.siteprep.com/shed-foundation-blocks/
Hope that’s helpful!
We are installing a 12×20 shed for gym equipment in Kentucky. Do you think concrete is necessary for that weight?
Hi Summer,
It depends if your shed will have a built-in floor or not. If it has a wooden floor, a crushed stone pad will be fine (basically the gravel can handle any weight that a wooden floor can handle). Obviously, if there’s no built-in floor, you’ll want a concrete foundation to also serve as the floor for your shed. Hope that’s helpful!
Hi! Thanks for all this helpful info! We plan to install a pre-built manufactured tiny home – the builders will block the building 15 inches off the ground. What type of site foundation should I be getting a quote for? I also saw you mention above that cement blocks are not ideal long-term. Is there a better option you suggest that I can request of them or will the builders not likely oblige that type of request? Thanks for your input!
Hi Jai, if your tiny home has a built-in wood floor, we recommend going with a gravel pad as described above. The builders may or may not offer that as a foundation option; if not, you may be able to hire a third-party site preparation company (that’s what we are) to install the pad. Ideally, you want to prepare the pad before the building arrives. You can see examples of completed gravel foundations here. We also have a guide to building your own gravel foundation here.
Hope that answers your question!
Hi, I had a question. I am putting up an 8 x 12 resin shed with a resin floor. Would you still recommend a gravel base over concrete or wood?
Thanks
Hi Lou,
The majority of customers that are buying a resin shed get a gravel foundation for their shed. This article gives a few more details: https://new.siteprep.com/do-you-need-a-foundation-for-a-shed/
I currently have an existing 12×20 shed that is on cinder blocks in Northern AZ Mountains. The floor is warping and no longer seems viable. I know we need some kind of foundation but unsure where to start or who to even contact…. I’m in need of professional advice. Please help!
Hello, you did not mention critters. Namely rats. My 8×8 shed, built several years ago is actually sinking because rats regularly make their homes under it. I sort of contracted with a guy to pour a 9×9 concrete floor pad, with a 1×2 foot rat wall/footing all around. I have kind of decided to seriously consider the crushed concrete and/or gravel option, as it seems cheaper, more doable and flexible should I have to move it or the shed. My question is give that, how deep should the gravel foundation be for such, and would this be effective in keeping rats from tunneling. Or, should I still dig extra deep around the perimeter for rat control.
Hi Taliyah,
Unfortunately, we don’t serve AZ (yet). However, we did create an in-depth how-to guide for building a gravel shed foundation, which you can find here: https://new.siteprep.com/how-to-install-a-gravel-shed-foundation/
If you’re not up to doing the job yourself, you may be able to find a landscape or foundation company that would be willing to install a pad according to the specs laid out in the guide.
Hope that helps!
Hi Arthur,
Sorry to hear about your rat problem! That’s one of the reasons we steer folks away from putting their shed on concrete blocks (as covered in this article).
We recommend going at least 4″ deep with the gravel. And yes, that should prevent any critters from burrowing under your shed!
We have a full shed foundation building guide here: https://new.siteprep.com/how-to-install-a-gravel-shed-foundation/
Hope that helps!
Morning,
I’m looking for advise on whether I should use blocks or skids under my shed which will be on a gravel foundation. Thoughts?
Hi Chris, we recommend skids. Here’s an article detailing why blocks aren’t the best option: https://new.siteprep.com/shed-foundation-blocks/
We are building a 12×20 ft prefabricated cottage with a floor and insulation. The interior is unfinished but we will install that a bit later. The manufacturer suggested that we use concrete because of the size of the building and the concern that gravel might settle over time. Is that justified? Also eventually we hope to add plumbing which might make a concrete slab a bit difficult and we certainly are intending to have electric as well.
Hi Will, we recommend using ‘3/4″ clean’ crushed stone for shed foundations and compacting with a plate compactor before placing the building. 3/4″ clean stone is 95% compacted at delivery and compacting locks the stone edges together to prevent settling.
That being said, if you’re planning to finish the interior with drywall, you do run the risk of having cracks appear as the building naturally flexes during use; if you’re finishing it with shiplap or tongue-and-groove paneling it shouldn’t be an issue. We would suggest following the manufacturer’s recommendation as they know best how their specific building will behave under certain conditions.
You can read more about our crushed stone recommendations here, under the section titled “Crushed Stone”.
1 want to put a 20x10ft wooden shed in my garden my ground is currently gravel topped with decorative stone is this suitable?
Also would I put it directly on the ground on blocks raised what are my options?
Hi Martin,
We don’t recommend placing a prefab shed on concrete blocks or decorative pavers (what I believe you’re describing). Our recommended shed foundation is compacted 3/4″ clean crushed stone (gravel) surrounded by a treated lumber perimeter.
We have a written guide on installing that type of foundation here, a video guide here, and an explanation of why concrete blocks aren’t the best option here.
Hope that’s helpful!
My site prep person suggested crushed asphalt instead of stone for under my shed. The shed will be placed between two large maples, which he says are likely to crack the foundation over time. In addition, a 10X16 hunk of concrete will harm the trees. Your opinion?
Sorry–addendum to my comment “which he says are likely to crack a concrete foundation over time.”
Hi Deb,
We don’t recommend concrete for prefab sheds with wood floors, specifically for drainage reasons. We recommend a foundation with ‘3/4″ clean’ crushed stone (aka gravel); the trees will not crack that kind of foundation.
As long as your foundation is level, well-drained, and well-compacted, it should be fine.
Deb,
Understood…thanks.
Hi
I am looking to install a customized shed that will be 12 X 20, wood flooring with vinyl siding. I am at a loss on what type of foundation to get. Our backyard seems to collect water from the neighborhood (in heavy rain), but its not standing water and it drys fairly easily. We want our shed to last a long time. Could you give your best recommendation?
Thank you
Would gravel be good for a plastic lifetime shed 15 by 8?
Hi Stephen,
We often install gravel pads for plastic/resin sheds. Here’s one we did not too long ago: https://new.siteprep.com/recent-projects/gravel,pennsylvania/david-c-gravel-shed-foundation-in-hanover-pa/
Hi Fatima,
If your shed will have a wooden floor, we recommend a gravel shed foundation 100% of the time. It will drain much better and keep your shed structure in good condition for longer. Plus, it’s often about 1/3 the cost of a concrete pad.
Thank you for all the information! I have a follow-up question regarding your response to “Stephen” about gravel pads for plastic/resin sheds…how do you recommend “anchoring” the shed to prevent movement in high winds?
Hi Chad,
We usually suggest that folks follow the anchoring recommendations/requirements of their local municipality and the shed manufacturer. We have a few more details in this article, under the section called “Local Ordinances > Anchoring”: https://new.siteprep.com/how-to-install-a-gravel-shed-foundation/#3-Local-Ordinances
Pound-in anchors with cables attached to the shed are one popular anchoring method. Something like this might be an option: https://www.homedepot.com/p/TIEDOWN-Storage-Shed-Eye-Anchor-Kit-59075/100318600
Hope that helps!
We want to install a living area shed on top of our aggregate concrete patio. we would want to install floorings also inside the shed. Do i need to put something on top of the concrete before i put flooring? Should I be putting anything around the base to seal the shed. We live in Toronto. We would like to seal it too so it wont be too cold inside during winter.
Hi Joe,
We don’t have as much experience with exposed aggregate concrete pads. The main question is whether or not your shed comes with a prebuilt wooden floor. If it does, you can put the flooring right on top of the shed’s wooden floor. If the shed has no built-in floor structure, you’ll need to put a subfloor down on top of the concrete before adding the flooring. You will also want to make sure the base of the shed is sealed from moisture. You may be best off contacting a professional contractor for a project of that scope.
Hope that helps!
Hi! I stumbled onto your site and it’s very helpful! I ordered a pre-fab resin Suncast shed (6’x5′).
The manual says we have to build one of their recommended foundations to ensure a valid warranty. The choices are 1) Concrete slab, 4″ thick; 2) Wood platform using exterior grade wood, set on pier blocks or footing. They provide plans for the cuts of lumber and plywood.
They also said a proper vapor barrier should be provided.
Which method would you recommend? And what do they mean by a vapor barrier?
Thank you!
Hi Cindy,
If those are your only two options to preserve the warranty, the concrete will be the more durable of the two. If budget is a large concern, the wood platform may be more economical (though not necessarily with current lumber prices). We personally recommend a crushed stone pad; it may void the warranty, but is the best all-around option in our opinion. So our recommendation is 1) crushed stone pad, 2) concrete pad, and 3) wood foundation.
As far as a vapor barrier, it’s usually a piece of plastic that goes under a concrete pad to keep ground moisture from soaking up through the concrete. You can learn more about them in this article. You can also see us installing a vapor barrier under a garage foundation in this video.
Hope that helps!
When we move into the home we have now, (Baltimore, MD) the ground hog (2) have took over the shed we had. The shed was torn down and it have been a year since then. We now ready to replace the shed. Should we go with gravel or concrete? With gravel, should steel rods or layer of chicken wire be place under the gravel to kept the ground hogs from digging their way back under the foundation?
Thank you in advance
Hi Karen,
Groundhogs aren’t typically an issue with the crushed stone pads we install. We compact the crushed stone as part of the process, so it’s not very easy for critters to dig through it.
Found some great information here to confirm some of my questions. However I want to put in plumbing in my shed/workshop. It will be at the front of our property where we use to have a Mobile Home. We have power, septic, water, security, additional parking and at least 6″ minimum of 3/4 gravel. (no concrete pad) We havent contacted codes yet, but want to have some idea if this is something we can do and be prepared for questions to ask. We are on 4acres. I’m 70 and really dont want to walk up to the house every time I have to go to the restroom! Can you give me some guidelines or if its not even an option. Thank you!
Hi Patty,
It’s hard to give real definite advice without knowing a bit more about the site and the specific building you’re considering. We often add electrical conduits to shed foundations we install; it’s less common for folks to add plumbing in their sheds, though not impossible. We more often see plumbing in garages and other large buildings where we install concrete foundations.
If you’re in the Mid-Atlantic US, feel free to request a quote on a shed foundation here or reach out via our contact page for more project-specific assistance. Hope that helps!
Hi, I didn’t own the house when the shed was built. But I have a shed that supposedly used to sit on a gravel pad, but over the years (definitely 15+ years, unsure how old the shed is), the soil and gravel ended up mixing together. The base of the shed seems to now be sitting directly on the ground (the PT wood on the outside base of the shed seems to be half way into the ground, about .75″ or a little more). After a rain there’s some residual water around the shed area and the surrounding soil close by the shed stays a little mushy for a few days.
For a new shed (regardless if it has a pre-built floor or not), to replace the current shed, what type of shed base would you recommend in that same area? And why? Thanks in advance.
Hi Jay,
It really does come down to what type of floor the shed has. If there’s a built-in wooden floor, we would still go with a gravel shed base. From your description, it sounds like the previous foundation may not have been deep enough; we recommend using a minimum of 4″ of compacted gravel (crushed limestone actually) beneath your shed. We have a complete shed foundation construction guide with additional details if that’s helpful.
If your shed doesn’t have a built-in wooden floor, you could consider a concrete pad and fasten the walls directly to the concrete.
Thank you for all of your helpful advice. I live in the northeast and I am looking into getting a large (somewhere between 12 x 24 and 16 x 24) shed for a home gym (and maybe home office down the road). It will incldue electricity, an AC/heater and insulation. I can get a prebuilt shed with wood flooring and use a gravel foundation, or I can get the shed without wood flooring (build on site), but I have to use a concrete foundation. The outside of the shed will be vinyl siding either way. The cost of the shed with the gravel / wood floor option is slighlty less expensive overall, but only by about 1-2 k. I am most interested in what option will be better long term (and that the shed is level of course.) So, in terms of value and longevity of the shed as a home gym/office, which would you recommend. Thank you again !!
Hi Michael,
We’d recommend that you also run this question by your shed manufacturer before making a final decision. From our perspective, if the cost difference is only a few thousand, a building with a concrete floor might be the best in your case. While prefab sheds are built to last decades, a properly built shed on a concrete slab may last even longer in a lot of cases. It’s likely to support your gym equipment just a bit better as well. Hope that helps!
I am having a paver “patio” replaced with a reinforced concrete slab.
This is along side my detected garage. We plan on building a 8×12 to 10×12 on this but it will not take up the entire space. Any recommendations would be appreciated. I was originally planning to build directly on the pad but am not seeing some comments about the pad being larger than the building.
Hi Chris,
The main thing is to make sure that the concrete pad drains properly. Otherwise, you could end up with water puddling on the concrete around the bottom of your shed and causing long-term moisture damage issues.
We want to buy a shed, pre-fab, 8×12. We are having pavers put in our back yard. We live in Arizona, Monsoons. We have concerns about gravel and critters making their home underneath, thus we thought we could build on top of the pavers but then we have concerns about drainage. Could you please give us the best advice for critter concern and drainage. Thank you.
A couple of ideas: (1) Try a gravel foundation (drainage is key) and then place a hardwire mesh around the bottom of your shed to keep out any critters. (2) Try permeable pavers (rather than non-permeable pavers) –these can help your foundation with any drainage issues.
HI, I am building a 12×20 shed for a woodworking shop. It will be located on my gravel driveway.
The soil seems to be a bit soft as we are in Western NC and it’s mostly clay.
I plan to put a 15′ x 23′ gravel pad down framed with PT 4′ x 4′ or 4′ x 6′
I will dig the area level and compact the soil. I plan to go with between 4″ and 6″ deep gravel and I will compact that as well. Do you think I will have any issues with settling since the clay can get soft when wet?
Make sure to compact the ground and the gravel. This article might help you a bit more: https://new.siteprep.com/how-to-install-a-gravel-shed-foundation/
Can I pour cement over a brick flooring in my shed? The existing flooring has sunk over the years due to rain and mosisture.
We just demolished our 12×8 shed that was sitting on a concrete
Slab. The shed had a prefab floor and was also sitting on 4×4 skids. The slab is in pretty good shape for being installed in 1986 (there is a name and year written in slab). However, we are buying a new prefab 12×18 shed with floors and we are unsure if we should add new concrete to expand to the desired size, add the crushed gravel to the slab, or take out the entire existing slab and start over. We do live in Midwest so freezing, critters, winds, and all of the other natural events are a concern. I read through your responses to the questions but haven’t really seen anything that speaks to an existing concrete site where you need to make it bigger for new larger shed. The local municipalities have their own rules for anchoring because of size but I am looking for just the best non-biased recommendation.
Feel free to reach out to us at (717) 799-7311 and maybe we can discuss it a bit more!
Hi Adriana, explaining this thoroughly here might be challenging. To provide you with better assistance, could you please reach out to us and provide us with more information? We would greatly appreciate it and will be able to assist you more effectively. https://new.siteprep.com/get-quote/