Storage Sheds: How to Choose a Shed Foundation
I wrote this guide for people new to shed building, and tried to stay away from technical terms. I hope it helps you have an understanding of shed foundations so you can make an informed decision about what type you need.
The most basic shed foundation
If your shed is relatively small -- 8' x 12' or smaller -- you can build it directly on the ground as long as it's fairly flat and level. If the ground is uneven, you can level it with a shovel. For a long-lasting shed base, be sure to use treated wood.
A gravel-based shed foundation
Another great do-it-yourself option is to use a gravel-based shed foundation. This takes more work, but is preferable if you live in an area with a lot of rain or temperature extremes. A gravel-based shed foundation has good drainage and is easy to level.
If your shed is 8' x 12,' dig out an area at least 9' x 13.' Fill that with gravel and level it. Then you construct what's called a pier and beam foundation, using nine 1' x 1' concrete paving stones in a grid pattern (three rows of three stones, with one stone in each corner, one in the center and the other four stones halfway between each of the corner stones). Level all the stones.
The next layer is your shed base, constructed as follows: Take three 4" x 4" treated lumber beams the length of your shed and place them parallel on the ground. Use two beams for the outside edges and put the other beam halfway between these two so it's your center beam. Then nail 2" x 2" treated lumber across the beams for your cross beams, stretching all the way from end to end. Each cross beam will be supported in the middle and at each end.
Poured concrete shed foundation
The final foundation is poured concrete, but this is generally for larger projects or for people who want to have the job done by a contractor, which is a much more expensive option.
Important:
Once you have built your shed base, it's absolutely essential that it's square. Here's how to check: Facing your shed, take a measurement from the near left hand corner of the shed base on the diagonal to the far right hand corner of the shed base. Then take a measurement from the near right hand corner on the diagonal to the far left hand corner of the shed base
If the two measurements are the same, your shed base is square. If they are not, you'll need to make some adjustments so each corner is at a 90 degree angle. When you finish building the shed base, check again to make sure it's square, using the same method.
I know from first-hand experience what happens when you don't. I built a shed a while back and didn't do the most basic thing: make sure the shed base was square. When I started decking the roof, I quickly learned I had a problem. I had quite a bit of trouble getting it square and that's why I'm stressing the importance of doing it right.
Some general tips:
Before you start building your shed foundation, check to see if you need a permit. Also check for any restrictions, such as how close you can build to a property line or existing structure.
Plan to build a shed in an area where water does not stand after it rains so you'll have better drainage.
If you're going to store equipment in your shed, like a riding lawnmower, you may need a ramp. Also, if you want electric service and/or water in your shed, you need to consider that before deciding on a foundation.
A good set of shed plans will explain how to place and level the paving stones in detail as well as how to lay out the area for the gravel.
I hope this article helps you make a more informed decision about what type of shed foundation you need.
The most basic shed foundation
If your shed is relatively small -- 8' x 12' or smaller -- you can build it directly on the ground as long as it's fairly flat and level. If the ground is uneven, you can level it with a shovel. For a long-lasting shed base, be sure to use treated wood.
A gravel-based shed foundation
Another great do-it-yourself option is to use a gravel-based shed foundation. This takes more work, but is preferable if you live in an area with a lot of rain or temperature extremes. A gravel-based shed foundation has good drainage and is easy to level.
If your shed is 8' x 12,' dig out an area at least 9' x 13.' Fill that with gravel and level it. Then you construct what's called a pier and beam foundation, using nine 1' x 1' concrete paving stones in a grid pattern (three rows of three stones, with one stone in each corner, one in the center and the other four stones halfway between each of the corner stones). Level all the stones.
The next layer is your shed base, constructed as follows: Take three 4" x 4" treated lumber beams the length of your shed and place them parallel on the ground. Use two beams for the outside edges and put the other beam halfway between these two so it's your center beam. Then nail 2" x 2" treated lumber across the beams for your cross beams, stretching all the way from end to end. Each cross beam will be supported in the middle and at each end.
Poured concrete shed foundation
The final foundation is poured concrete, but this is generally for larger projects or for people who want to have the job done by a contractor, which is a much more expensive option.
Important:
Once you have built your shed base, it's absolutely essential that it's square. Here's how to check: Facing your shed, take a measurement from the near left hand corner of the shed base on the diagonal to the far right hand corner of the shed base. Then take a measurement from the near right hand corner on the diagonal to the far left hand corner of the shed base
If the two measurements are the same, your shed base is square. If they are not, you'll need to make some adjustments so each corner is at a 90 degree angle. When you finish building the shed base, check again to make sure it's square, using the same method.
I know from first-hand experience what happens when you don't. I built a shed a while back and didn't do the most basic thing: make sure the shed base was square. When I started decking the roof, I quickly learned I had a problem. I had quite a bit of trouble getting it square and that's why I'm stressing the importance of doing it right.
Some general tips:
Before you start building your shed foundation, check to see if you need a permit. Also check for any restrictions, such as how close you can build to a property line or existing structure.
Plan to build a shed in an area where water does not stand after it rains so you'll have better drainage.
If you're going to store equipment in your shed, like a riding lawnmower, you may need a ramp. Also, if you want electric service and/or water in your shed, you need to consider that before deciding on a foundation.
A good set of shed plans will explain how to place and level the paving stones in detail as well as how to lay out the area for the gravel.
I hope this article helps you make a more informed decision about what type of shed foundation you need.
