Many of our clients are come to us wondering, “What’s the best shed foundation: 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.
Gravel is generally better than concrete for a shed foundation
As mentioned above, gravel foundations win out 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.
Photo credit: http://shabbyglam.blogspot.com
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.
Photo credit: Sheds Unlimited
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. If you’re only installing a shed, concrete 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.
So, is a concrete shed base better or stronger than crushed stone? It depends…
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.