1. The shed foundation should support the weight of the shed and spread it evenly over the ground on which it rests
2. Protect the wood at the base of the shed from moisture coming up from the ground.
3. Include features to stop vegetation growing beneath and around the shed.
A fourth point applies to larger sheds:
4. Stop it moving throughout a range of climatic conditions (some soils change in volume with moisture content, frost and action of tree roots).
Due to the size, weight and longevity of house foundations they are designed and built not to move. They are expensive and expected to last a long time. This contrasts with shed foundations where some movement can be tolerated.
Normal house foundations are dug deep so that the foundations are supported on a stable layer of subsoil. This is to avoid the main causes of foundation movement;
A house needs to be still so that connections to water, sewage etc are not broken. A lso with large buildings if one side of the house moves relative to the other the building starts to crack and tear itself apart.
This does not necessarily apply to sheds.
To achieve the cheapest and simplest form of foundation appropriate for your shed, think about the size and use of the shed, its location within the garden and possibly the sub-soil type.
If you are planning a small shed, read the next couple of paragraphs to point you to the next article to read, however for larger sheds I suggest you read right to the end of this article.
Small sheds and stores can often be situated on an existing patio or hard-standing.
can be sited on crushed stone with either treated wood foundations (timber sleepers/railroad ties will do just nicely)or concrete foundation blocks or paving slabs.
However before you decide on the traditional have a look at a new type of shed base that can save you time, effort and money. Click here to find out about the plastic shed base.
more substantial shed foundation plans are required. A concrete shed base may be the solution. A concrete slab foundation has the advantage over timber floors if water is to be used on the shed floor or wet equipment to be brought in often.
Alternatively, a shed pier foundation can be used as a more easily constructed, time and money saving option.
If the ground slopes gently or steeply it can make construction a bit more tricky, but nothing that can't be overcome as this article on building a shed on sloping ground shows.
If you answered Yes! to any of these questions then pop your contact details in the box below to keep updated with all the latest from this site.
Once a month, on the first of the month.
Your email address will be kept confidential and won't be shared.
Easily unsubscribe at any time. I hate Spam as much as you do!
Small sheds literally move up and down by an inch or two in the course of a year and will not be noticed or matter to anyone. The shed sort of 'bobs up and down on a sea of soil'.
For larger sheds, foundation movement can be a problem for two main reasons:
- The shed is connected to another structure with a different foundation type that is moving in a different way or services are connected in to the building.
- If one end moves and the other doesn't, then the floor will start to slope or the building crack and distort.
The main solution to these problems is to make a foundation sufficiently deep that it is on ground that is not going to change volume.
As the ground freezes in the winter months, the soil expands and lifts whatever is on top of it. The solution to this problem is to make the foundation deep enough so that the underside is below the frost zone. In the UK, the frost zone is about 600mm, for colder countries it can be a lot deeper.
For some soils, mainly clays, the volume changes with moisture content. Moisture content can change due to a very dry summer, a very wet winter or a tree growing and sucking the moisture out. As moisture is sucked out of the soil it shrinks (after a tree has been cut down the soil regains its moisture content and expands). For these reasons think carefully before locating a larger shed close to rapidly growing tree or one that has been recently cut down.
Finally...if a shed moves, it is nearly always possible (if a bit inconvenient) to re-level it later.
When deciding on your shed foundation type, remember that the larger the shed and the more often it is used, the more substantial the base needs to be.
Click below to see contributions from other visitors to this page...
Gentle Slope To Hardstanding...
Hi John, Fantastic site. Lots of very helpful information, however I do have a question that I hope you might be able to help with. I've decided …
Plastic Pallets as foundation?
I scored most of my materials free, or at 70 % discount from H. Depot. I got some free plastic pallets and want to use them as a foundation for the …
Reinstating shed foundation
I have removed the foundation and floor of a 25 yr old 12' x 20' shed that was built with 4x4 skids set on the ground and 2x4 used as floor, end and rim …
Building on a slope
I am building a 10x12 shed and it is on a slope. The plans call for the floor to sit on three 4x4s. I was thinking of leveling it by using 12x12 concrete …
Suggestions on sonotube size for a 12' x 20' shed on unlevel ground
Hi John, I'm thinking about putting up a 12'x 20' shed. The ground where it is going is sloping and (at this point anyway) very uneven. I was thinking …
Building a shed on or above a low spot of yard that builds up water.
Whats the best solution to building on a section that accumulates water during rain? Don't want shed to sink or shift. Shed type is a 10' X 10" Suncast …
Why do you need gravel beneath a shed?
Do I really need stones or gravel under my shed, if I do why is that? Also how can I keep spiders and bugs from sticking under my shed? Shedman …
Shed foundation on sloping yard
Hi, I am trying to build a 10' x 10' Gable shed on my rear yard which has a slope If ABCD is my shed with A as highest point on the yard then B is …
Preparing the ground for a shed
We are preparing the ground for a shed! However there is a slight slope - about 20 degrees. What is the best way of dealing with this? -Levelling it …
Building a shed base
I am thinking of buying a shed and I am not sure how to do the foundations. The shed size is 2.4 wide by 3.0 depth. How deep should the foundations …
What is the best foundation for a small shed?
What is the best foundation for a small wooden shed? Reply: Hi Sharon, Thanks for your question. It depends a bit upon the use you have for …
Pier Foundation for a Shed
I have to build my 10' x 10' shed close to a tree with exposed roots so I am going to elevate it and I was thinking of using concrete blocks to build it …
Sona tube size for 12'x16' "saltbox" bathhouse-cabin ?
I intend to build a "saltbox" style guest cabin-bathhouse between our main cabin and the lake. This is an off the road place (Alaska) and I'd like advice …
Building down to increase height of shed
Because we cannot build up too high above the current fence in our townhouse development I thought I could get around that by digging at least a foot or …
Which plastic base is best?
Hello John, I will be putting together a 6' x 8' shed (Eightbisix Shack Up) and have seen your info on plastic bases which I really like the idea of. …
How can I make a good base? I am older and find lifting heavy things a problem.
Shed Base for sloping site
Do you have any design tips for a shed base for a sloping site? The shed is to be either 10x16 or 12x16 - with the larger dimension running up the slope. …
Sunken shed Not rated yet
Hi all. I'd like to erect a 12'x12' substantial shed to use as an art space. It will be near a boundary and the regs state that it can only be a max …
Foundation problem - Observatory Shed Not rated yet
Hi I have a problem, perhaps someone can help. I'm looking to build a 'roll off roof observatory'. That is a shed for my telescope with a roof that …
Foundation problems in existing shed Not rated yet
I have a shed / cabin which was built 50 years ago by my father which is used as a bothy for weekend visits. The building is very small (5.5m x 3m) plus …
shed foundation: concrete 'feet' plus timber Not rated yet
Hi Mr. Coupe, I will be building a shed in my backyard this year to use as a workshop. I would like to build a structure probably at least 10x12', …
protecting the concrete base of a shed Not rated yet
Hi, We have built a 3 meter x 3 meter concrete slab for our wooden shed which will be 2.98 meters x 2.98 meters at its base. The slab sits on a slight …
Building a shed on concrete slab Not rated yet
I want to build a shed (7' x 14') on an existing slab, which is somewhat larger than the shed will be. The slab is at the level of, or slightly below, …
Plastic shed base availability in the U.S.? Not rated yet
I enjoyed your articles on shed foundations, & got excited about the EcoBase--only to discover no information about its availability in the U.S. Shucks! …
Shed Foundation Question Not rated yet
I am in the process of relocating a 12x21 storage building. I plan to have it placed on center blocks with gravel drainage underneath. How much clearance …
Keep in touch with our monthly newsletter
Shed Building Monthly