Shed Foundation Piers: The Ultimate Guide

In general, we recommend gravel shed foundations as the best all-around shed base. However, some townships require frost-proof shed footings and/or shed anchoring.

Of all the frost-proof shed foundations available, shed foundation piers are one of the best options. They strike an excellent balance of affordability, ease of installation, and great support/anchoring for your shed. If piers are required in your location, we recommend combining them with a gravel shed foundation.

Introduction

Can you put a shed on piers?

Yes! Poured concrete piers are one of the most affordable and durable shed footings available. This is primarily true in situations where a frost-proof base is required for your shed. (Plus, what’s the point of writing this article if you couldn’t put a shed on piers!?)

What is a shed pier foundation?

A shed pier foundation consists of 4 or more concrete piers with diameters of 12”-24”, which are poured to a depth at least 6-12” below the local frost line. Ideally, shed piers should be combined with a gravel shed foundation. This creates a frost-proof base that supports all parts of the shed equally while providing excellent drainage.

Poured piers vs pier blocks for sheds

There are two common products that are both referred to as “shed foundation piers”:

1. Poured concrete piers
2. Concrete pier blocks (aka “deck blocks”)

In this article, we’ll be dealing specifically with poured concrete piers for sheds. We don’t recommend pier blocks for sheds because they do not provide frost-proof structural support and are at risk of shifting over time. You can read more about why shed foundation blocks are not a good idea here.

Planning your shed foundation piers

Before you get your tools out, it’s a good idea to develop a plan for your shed pier foundation. It’s important to first determine if your shed requires foundation piers. If it does, you’ll want to figure out what size and how many cement piers your shed needs.

How do I know if I need foundation piers for my shed?

In most cases, your local municipality, township, or county will determine when frost-proof footings (aka shed foundation piers) are required. Once you’ve decided on the size and type of shed you’re building or buying, check with the local building department to see what they call for. You can refer to our shed footings guide for a breakdown of the most common footing requirements for a shed.

Can I place my shed on concrete piers alone?

While the technical answer is “yes”, we strongly recommend combining your shed foundation piers with a gravel shed foundation. A gravel shed foundation distributes the weight of your shed more evenly across all parts of the shed’s sub-frame. Plus, it prevents weed growth around the shed and improves drainage. From our experience, gravel foundations support sheds so well that the foundation piers (even when required by code) serve more as anchoring points than as structural supports. (Of course, we still recommend that you follow your local building regulations!)

How much concrete do I need for shed foundation piers?

You can use a formula (see below) to figure out how much concrete you’ll need for your shed piers. (Of course, if you hire a shed foundation company, they will take care of all the calculations!)

The formula to calculate how much concrete you need for shed piers is as follows:

(# of piers)x(Pier radius in inches)²x(Pier depth in inches)/14850 = Cubic yards of concrete

Commercially delivered concrete (from a concrete truck) is sold by the cubic yard. For smaller projects, it’s easiest to mix the concrete on-site using a ready-made bagged concrete product, such as Quikrete® or Sakrete®. If you buy your concrete in 80lbs bags, it will take about 45 bags to equal 1 cubic yard.

So, the calculation for an example project with ten 16” (8” radius) piers poured to a depth of 36” would look like this:
10×8”²x36” /14850 = 1.55 cubic yards (or 70 bags of 80lbs concrete mix)

This formula raises several other important questions, however!

How many concrete piers do I need for a shed?

Your local building codes may specify this based on the size of your shed. If not, a general rule is one shed foundation pier at least every 8-10 feet along the width and length of your shed.

For example, you would need 6-9 piers for a 10×12 shed. You would need 15-18 piers for a 16×40 shed.

If your shed has wooden runners under it, you will want to place the concrete piers in a layout that will allow you to anchor the runners to the piers. (There’s more on anchoring further down.)

What diameter should concrete shed piers be?

Again, this might be defined in the local building code. Otherwise, 12” shed foundation piers are sufficient in many cases.

In general, smaller piers are needed when combined with a gravel shed foundation, since the gravel pad helps to support the weight of the shed. In these cases, the primary purpose of the piers is anchoring, rather than structural support.

If the piers are the sole support beneath the shed, it’s advisable to choose a larger pier diameter.

If you hire a shed foundation company, they will be able to give a specific recommendation for your shed.

How deep should concrete shed piers be?

Extending shed foundation piers to 12” below the local frost depth is a good rule of thumb. Depending on your location, your shed foundation piers could be 24”, 36”, 48”, or even more. However, this is one specification that the local regulations will almost certainly define for you.

Tools for installing shed piers

You will need the following tools for installing your shed foundation piers:

• Auger (optional) – A power auger is the fastest way to dig the holes for your shed piers. 1-man power augers are too small for a project like this since they typically have a maximum diameter of 8”. Here are several common types of augers that could work:
  • 2-Man Auger – Good for holes up to 18” in diameter. It requires two people to operate, both of whom need to be in relatively good physical shape. 
  • Towable Hydraulic Auger – Good for holes up to 18” in diameter. This is a standalone unit that can be towed behind a vehicle. It can be operated by one person.
  • PTO Auger – Typically good for holes up to 24” in diameter. This unit attaches to the 3-point mount of a tractor and is powered by the PTO drive. A tractor with at least 20-40HP is required, but it only requires one person to operate.
  • There are also several other auger configurations, including those mounted on a mini excavator or skid steer (what we use). For piers over 24” in diameter, you may need to use one of these larger augers or hand the job off to a professional foundation company. You can rent augers by the day or week (such as here or here).
• Concrete mixer – The most common mixer sizes are between 3.5-9 cubic feet, although there are some as small as 2 cubic feet. You can rent a concrete mixer by the day.
  You can also mix the concrete by hand in a wheelbarrow or directly in the pier hole. However, this is more physically demanding and may not mix the concrete as thoroughly.
• Float (magnesium) – For finishing off the tops of the piers. You’ll want a float that’s shorter than the diameter of your shed piers.
• Laser level – This is the easiest way to make sure your shed piers are completely level. A string level could also work.
• Marking paint – For marking shed pier locations.
• Plate Tamper – You’ll use this to pack the dirt at the bottom of the hole before pouring concrete. Alternatively, you can use a digging bar with a tamping end.
• Post hole digger (clamshell digger) – You can use a post hole digger to dig the pier footings by hand if you don’t have access to a power auger. This is a more time-consuming and physically demanding option, but it does provide an excellent workout! Even if you use an auger, you will want a post hole digger to clean out the bottoms of the holes before pouring concrete.
• Saw – For cutting the concrete tube forms. There are a variety of saws that could work for this, including a hand saw, a reciprocating saw, a circular saw, or a chainsaw.
• Shovel – For shoveling concrete and general site clean-up.
• Tape measure – For checking footing depth, pier placements, etc.
• Utility knife – For trimming/removing forms after the concrete is poured.
• Wheelbarrow – For moving concrete, dirt, etc.

Materials for installing shed piers

You will need the following materials for installing your shed foundation piers:

• Concrete – For most small projects, it’s easiest to buy a bagged concrete mix (like Quikrete®) and mix it on-site. We recommend purchasing 80lbs bags of concrete mix.
  You can also have the concrete delivered commercially (with a concrete truck), but you will generally have to pay a flat delivery fee, plus a short load fee if you order less than a full truck (10 cubic yards). In general, you will only want to consider having concrete delivered for larger projects, such as 2+ cubic yards.
• Concrete Form Tubes – These forms are often referred to by the popular brand name Sonotube®. They are available in a range of diameters, from around 8” and up in 2” increments. Concrete form tubes are typically sold in lengths of 48”.
• Gravel (optional) – Some people like to add a bit of gravel in the pier hole before pouring concrete. This is most common when the shed pier will be supporting a lot of structural weight. We don’t typically find this to be necessary.
• Rebar (optional) – Adding rebar for extra strength is important when piers will be bearing a large structural load. We don’t find it necessary in most shed foundation pier applications (especially when combining piers with a gravel shed foundation as we recommend).

How to build shed foundation piers

So, how do you build a pier foundation for a shed? Although there are several steps, it’s a relatively straightforward process overall.

(If you plan to combine your shed foundation piers with a gravel shed foundation, it will be easiest to build the gravel pad as a second part of the project, after the piers are in place. To get the best overview, it may be helpful to read our guide to building a gravel shed foundation before starting either part of the process.)

Here are the steps for building shed foundation piers:

1. Mark shed pier locations

Once you decide on the location for your shed, mark lines at each of the shed corners. It’s a good idea to double-check that there are no tree roots or utility lines in the area where you’re planning to dig.

If your shed will be next to a fence or driveway, it’s a good idea to use that as a starting point and make sure the first side of your shed foundation is parallel. Once you’ve marked all four corners, take diagonal measurements as well. The diagonal measurements should be equal in each direction to ensure that the shed base is square.

If you will have multiple rows of shed piers, mark each row across both the length and width of the shed. You will want to end up with an X marking the spot where you will set each pier for the shed.

An important note: Depending on how it’s constructed, the runners beneath your shed may be inset from the sides of the shed by up to 12”. You will want your shed piers to be approximately centered beneath the runner, rather than centered on the exact corner of the shed. Be sure to find out where the runners will be on your shed and mark your pier placement lines accordingly.

2. Determine grade/site slope

If your site has a slope, you’ll need to measure it. It’s important to determine the grade exactly since you will pour the shed foundation piers to compensate for it and level the shed. It’s easiest to use a laser level, but you can also use a string line level or a stick level and straightedge to get the job done.

To measure the slope with a laser level, place the laser at the highest point of your site. From there, move around the site and use the laser receiver to take readings where each of your shed foundation piers will be. By moving the receiver up or down the transit rod, you can find the exact height difference between the highest pier location and every other pier. You may want to draw a simple diagram of all the pier locations and their respective height differences. You can refer to this diagram when placing your pier forms.

Our gravel shed foundation guide gives additional details on measuring shed site slope here. You can also find laser level tutorials here and here. The video below gives a helpful overview of the general process of finding the slope of a site.

Keep in mind that if your site has a slope of more than a few inches, it will be easiest to access your shed if the door is placed on the uphill side. It’s certainly possible to dig out the site so the door is level with the downhill side of the slope, but it’s a lot more work. If a downhill door is your only option, you may want to consider hiring a professional shed foundation company to prepare the site.

3. Excavate the pier holes

It’s easiest to dig the shed pier holes with a power auger. When we install shed foundation piers, we dig the holes with an auger attached to a mini skid steer. As mentioned above, there are a number of auger types that will do the job.

Of course, you can also dig the footings by hand with a post-hole digger. (If you dig by hand, you can probably also cancel your gym membership! 😉)

Pier footings are measured by diameter in 2” increments. While there are many sizes available, the most common shed foundation pier diameters are between 12” to 16”. Check the local code to see what’s required in your case.

Dig the footing holes to whatever depth is required by your municipality or the International Residential Code. If not otherwise specified, it’s good to go at least 12” below the local frost line. For instance, 36” is the standard depth for shed foundation piers here in the northeast USA.

Some municipalities require shed foundation pier holes to be inspected before the concrete is poured. You’ll want to check ahead of time if this is required in your area. If so, try to schedule the inspection for the end of the same day when you’re excavating, or for the day after. That will keep your project from being held up while waiting on inspection.

4. Add the pier forms

Once the footing holes are at the proper depth, insert the pier forms. Sonotube® is the most well-known brand, but they are also made by many of the ready-to-mix concrete companies. You should be able to find them at any large home improvement store by searching for “concrete form tubes”.

You don’t necessarily need to insert the tube the entire way to the bottom of the hole. We often cut the tube forms to extend about 12” below ground. That keeps the visible part of the shed pier looking nice and lets the concrete completely fill the rest of the footer hole.  Make sure the top of the hole is tight enough to hold the form in place if you do this.

Shed pier forms come in 48” sections. You can cut them to length with a handsaw, chainsaw, circular saw, reciprocating saw…basically any kind of saw!

If your site is on a slope, remember to extend the forms far enough above ground on the downhill side to level the shed. It’s best to have the top of the forms almost exactly where the top of the finished pier will be. However, it’s better to extend it a little higher than to have it too low. 

5. Pour the shed piers

For larger projects, consider buying the concrete premixed and having it delivered by truck to your site. You can typically purchase concrete by cubic yard, though you may need to pay a convenience fee if you order less than a full truckload (10 cubic yards).

If you’re only pouring a few shed footings, you can mix up your own concrete by hand. Just follow the mixing instructions on the concrete bags when you purchase them. Generally, you’ll add about 1 gallon of water per 80 lbs bag of concrete mix. (As an example, you can see the instructions for Sakrete® concrete mix here.)

The best ways to mix concrete for your shed piers are:

1. Using a concrete mixer – This will give you the most thorough and consistent mix. It’s also the least strenuous! Make sure to use a mixer that’s designed for concrete specifically. (Some are intended only for mortar without stones or aggregate.)
2. Mixing by hand in a wheelbarrow – If you don’t have a concrete mixer, you can pour your ingredients into a wheelbarrow and mix them with a shovel.
3. Mixing by hand in the pier hole – This is the quickest way. It won’t result in as thorough of a mix, but it will save you time. This may be sufficient if the piers will be combined with a gravel pad. The gravel pad will bear much of the building load while the piers simply provide an anchor point.

The video below gives a good, quick overview of how to mix small batches of concrete in a mixer.

If your piers will be supporting a large load, you can add rebar for extra strength. To do this, add up to 4 lengths of vertical rebar in each pier. (This is generally not required for most average-sized sheds.)

To prevent concrete honeycombing, it’s a good idea to tap the sides of the form with a hammer or other tool. This releases air bubbles and shakes the concrete into every part of the form.

Use a concrete float (magnesium floats are ideal) to finish off the tops of each shed foundation pier. You’ll want to use a float that’s shorter than the diameter of your pier. Check the height of the concrete in each form with the laser level to make sure everything is level. If needed, you can add or remove concrete to bring it to level, then refinish the top of the pier with the float. The following video gives an overview of concrete float types and how to use them to finish concrete.

6. Cure the shed piers

If your piers will be bearing most of the structural load of the building (i.e., not combined with a gravel pad) you should let them cure for 3-7 before placing the building on them. It takes concrete about 28 days to fully cure, but it has much of its structural strength within the first week.

For highly technical, load-bearing applications, it’s recommended to “wet cure” concrete by keeping it covered and damp for the first 3-7 days or coating it with a curing compound. However, this is unnecessary for shed pier applications in almost every case.

Once the concrete is cured, you can use a utility knife to cut and remove the visible parts of the form. Backfill dirt around the shed piers and make sure it’s tamped down well.

7. Install anchors

Technically, the order of this step depends on what type of shed anchors you use.

We recommend simple L-brackets, installed with a concrete bolt or large Tapcon® into the shed pier and a lag into the shed runners. This style of anchor is installed after the shed is in place.

Alternately, you can embed concrete anchor straps into the shed piers during pouring as part of step 5. However, this requires you to know exactly where the shed runners will fall in relation to the piers (to an accuracy of about ½”).

Conclusion

After your shed foundation piers are in place, you can finish building a gravel shed pad around them. Once that’s completed, you’re ready for your shed!

If you’re not ready to tackle a project like this yourself, you may want to search for a professional shed foundation company in your area. A shed foundation pro will also be able to make specific foundation recommendations based on your site, planned building design, and intended use.

If you’re in the Mid-Atlantic or Northeast USA, we’d be happy to give you a free shed foundation quote ourselves. Best wishes for your project!