Is decking a good shed base? Yes and here’s why

A shed is a useful storage area for any garden. It provides somewhere convenient to store garden tools, Such as your lawn mower, and other hand and power tools. It can also be used for other items, such as bikes, and even hutches for small pets.

If you are buying a new shed, one consideration is where it will go. Ideally you need some kind of solid base. This will avoid two main things from happening

  1. It will avoid moisture and damp entering the shed. If this did happen it wouldn’t be long before your shed begins to deteriorate from the effects of the moisture.

  2. Avoiding subsidence. If there is no solid base, and you shed is placed directly on your lawn, there is also a risk of subsidence and movement. The term subsidence seems a little dramatic. This is something we would usually associate with major structural issues in a property. However, the principle is the same. If a shed doesn’t have a solid foundation, it will be subject to movement.

Decking can be a good option for building your shed base. They are strong and durable (if built correctly) and are aesthetically pleasing. They are also pretty easy to construct and cost effective.

is decking a good shed base

Other good options are paving stones or solid concrete slabs. However, both of these are going to be slightly more expensive, and not quite as straight forward as a small deck.

Advantages of building a deck for your shed base

There are several advantages to building a deck for your shed base. These include:

  • Cost – Your deck will usually consist of a treated timber frame, Treated decking boards, some treated posts and some post mix or concrete. So, the overall cost should be pretty low

  • Relatively easy to maintain – Over the years the timber boards may need replacing, but this is not a major issue. The timbers are pretty easy to replace. The biggest issue here, is you will need to move your shed temporarily. However, once this is done, boards can easily be screwed up and switched for new ones.

    Also, if you wanted to avoid this entirely, and are prepared to spend a little more, you could opt for composite boards. This type of decking board is likely to outlive your shed.

  • If your using timber decking, you can also stain it the same colour as your shed. This can add a nice aesthetic to the entire shed area.

Is decking a strong enough base for a shed?

I have seen a few people online, suggesting that a deck might not be strong enough to support a shed. I’m not sure how they came to this conclusion, and I completely disagree with it. If you build the deck well, using timbers that are appropriate for the weight they will be supporting, it can be a perfect option.

Let’s just consider what a deck actually is. It consists of a timber joist frame and timber boards laid on top. Sound familiar? It’s actually very similar to the floors you walk on every day in your house.

In a standard property, joist can range anywhere from 6-12 inch in depth, The size of the joists in different properties will vary based on the span they cover.

As an example, a 147mm x 47mm (7x2inch) joist, can span over 3 meters at 400mm centres. This will have a load bearing strength of greater than 1.5kN/m2 (kilo newtons/square meter).

Obviously, there are some differences between the two. The main one being, joists in a house are in a property with solid foundations. However, these floor joist regulations regulations are based on the timber strength only. They state that the joists should be able to support the dead load from above, without sagging.

Therefore, if we use appropriately sized joists for our deck base, the same will be true, and there will be no chance of sagging under the sheds weight.

The next element that we need to get right, is a solid footing for the deck to sit on. My personal preference for this, is 4×4 inch treated posts and concrete (postcrete). I then fix the posts in each corner and every 1.6m, securely bolting them to the frame.

Basically, if your deck is built with the correct timber and it has posts supporting it, it will be a very strong structure. Easily strong enough to support a shed.

Also, the posts ensure that no span is bigger than 1.6m. Therefore, the joists are extremely well supported and will be able to support several 100kg per m2 with no problems at all.


From a structural and strength standpoint, a deck is easily strong enough to use as a shed base. They are used to support plenty of other heavy items such as hot tubs, garden furniture, and even heavy snow.

Also, they are relatively cheap and easy to build, and they definitely look more attractive than an ugly slab of concrete.

You just need to ensure, that you take the time to build it properly. For example, build your frame with decent sized pressure treated timber. Make sure you have even spaced support posts, that are set solid in a concrete mix. These two things combined will provide an extremely solid frame. Also, your decking boards will tie everything together making the structure even stronger.