How to Build a Foundation for a Shed
Low Cost Construction Technique for Small Foundations
Knowing how to build a foundation for a shed is the all-important first step of adding barn space to your farm or homestead. Laying a strong foundation for any project is key to the longevity of the structure, regardless of construction type. Not all structures require the same kind of foundation, nor does every foundation type work for every terrain. Let’s look at the more common foundation types, when to use them and how to set them up.
How To Build A Foundation For A Shed
First and foremost; can you build (or place) a shed where you want it? Do you have space? Will your local building codes allow you? Is your insurance company willing to cover it, and at what cost? All these questions need to be answered before you commit to spending your time and money on a project like this. After all, who likes an unwelcome surprise like a cease and desist letter from your town office?
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Do you have a flat space to work from or do you need to do some site work first? Even if the area looks level, you need to verify that it is. Sometimes the area you thought was level has a grade to it, which could equate into a lot of height for your foundation to make up for.
To check the level of your area, I suggest using the cheap string method. Measure out where you want the shed and stick a wooden stake or steel fence post at each corner. Run a string and string level around those posts and see what you get. Doing this also helps you visualize the space you need and the space your future structure will occupy.
If you’re looking into how to build a chicken coop from a garden shed, especially a prefab garden shed; start here. Gravel pads allow you to build up the ground with a permeable material that levels easily. Gravel allows water to seep down and away from your shed and resists puddling, which will extend the life of your investment. Many local governments will be happy with gravel because it’s a “semi-permeable” surface, and it’s not as permanent as concrete. It also makes for a nice aesthetic touch, since there usually will be a border of at least a yard all the way around your shed.
The downside to gravel pads includes the cost. If you need to make up for a lot of elevation change, such as a two-foot or higher difference in level, gravel can quickly add cost to your build. Not everyone has a tractor to spread this material either, or even if you do, do you have the confidence to level and compact it yourself? Don’t forget that if your gravel pad sinks, the shed manufacturer may not re-level it for free.
If you’re researching how to build a foundation for a shed you’re building yourself, then you’ve probably already seen concrete patio blocks used as piers. Concrete block piers are simple, effective, easy, and cheap to make. Block piers are exceptionally simple to work with when your shed is being built on site and can accommodate some significantly unlevel ground.
When I built my 10 by 16-foot brooder barn, I used this method instead of going wild with site prep. Call it lazy, but the patio block foundation was the quickest, easiest, and most cost-effective way to counteract the unlevel terrain. This is why all the online instructions on how to build a chicken coop include block piers as their desired foundation.
Concrete block piers are great for building sheds on location, but they have limits. Standard patio block piers can only go so high until they pose a risk of shifting and collapsing. Also, concrete patio blocks can be difficult to place once a prefab shed has been delivered, so I’d avoid this type of foundation for prefab structures.
If you can’t or don’t want to do major site prep to compensate for a significant grade, consider using a poured concrete pier. Concrete piers eliminate the concern of shifting blocks and give you the opportunity to dig below your frost line. Digging down and placing concrete footing forms (those cardboard or plastic concrete tubes) deep into the ground will help you avoid frost heaving, and give you a very stout foundation to build a shed on.
The downside to pouring concrete piers is that you need to work with concrete. On a big project like this, it can be very labor intensive to mix and pour your concrete and it’s not cheap to have a small load delivered by a cement company. You may be lucky and have a local company that does mixing on site from their truck, which would likely be more cost-effective, but be sure of this long before you start your project. Additionally, your local building code enforcement may or may not object to the permanent nature of the foundation, or having a concrete foundation may alter your tax liability in their favor.
Post And Beam
If getting a cement truck to your building location is not practical, but you still need to make up for significant height differences in the building site consider a post and beam foundation. Sinking poles in the ground, either pressure treated poles or repurposed telephone poles, is an economical and practical backup plan. Be sure you use substantial lumber, such as 8″ by 8″ nominal timbers and make sure you have a strong junction between your upright poles and your top cross beam(s). When you do drop these poles in the holes you’ve dug, I still suggest setting them with a bagged instant concrete mix for added security.
If you’re looking for how to build a goat barn, farm shop, or large shed that requires a hard, impermeable floor, then concrete is your best bet. Concrete pad construction does require some planning, site prep, and specialized tools, but it’s eminently doable. My father and I poured a simple concrete pad to set our 1,000-gallon skid tank on years ago, and it was a rather straightforward affair.
One word of caution; if you plan on pouring a pad bigger than six-foot square, I’d highly recommend ordering a load of concrete to be delivered by truck. Unless you’re a glutton for punishment, you’ll doubtfully enjoy mixing that much cement yourself. A concrete pad is costly compared to your other options, but if you want a shed with a concrete floor, then the investment will pay off. You can also expect a little more pushback from your local code enforcement since a concrete pad is a permanent foundation.
What experiences do you have with any of these foundations? How did they work out? Let us know in the comments below and start the conversation!