How to lay a concrete shed base

UK Home Improvement

How to Lay a Concrete Shed Base

Taking the time to create a solid, level concrete shed base will ensure the long-term safety and stability of your new shed. It’s an important part of the process, and it’s relatively straightforward. If you have a few tools and some DIY knowledge then read on to find out how to lay a concrete shed base.


Calculating costs and materials for a concrete shed base

You can save yourself some of the hassle (and maths!) by ordering a delivery of readymix concrete for shed bases. If you are mixing concrete for a shed base yourself, you will need to know the ratios and quantities of sand, cement and aggregate required to make the desired concrete mix.

When working out how much readymix concrete for shed bases you’ll need to get the job done, simply put your measurements into a concrete calculator. Measure the length and width of the shed base (make sure it’s at least 300mm or 12 inches larger on all sides than the size of your shed). A depth of at least 75mm of concrete is ideal for most domestic concrete shed bases.

There are many different types of concrete so make sure you find the right concrete mix for your shed base.


Location and access

It’s well worth planning the location of your shed properly and considering all options before going ahead and laying a concrete shed base. If you need access to water and power in your shed, plan ahead to make this as easy as possible. Make sure there is enough space to access the sides when building your shed, it will also help to have the extra space when it comes to painting and maintenance.

Try to avoid placing a shed in a very damp or shady spot and leave at least one metre between your shed and any nearby walls to reduce the likelihood of any damp problems.

Weather, tools and materials

Before you start your project, make sure you have all the tools you need, check the weather forecast and arrange for a delivery of readymix concrete to arrive once the pour site is ready.

Level the site

Make sure your site is level as it will be much easier to lay a concrete shed base and build a shed on level ground. A level base ensures the weight of your shed will be distributed evenly, meaning it will last longer too. 

If the area isn’t level, then you’ll either need to level it or consider an alternative area to house your shed.

Marking out the area

Before starting work, measure out the area you will need for your shed and mark it carefully using pegs and string. Remember to add about 300-400mm of extra space on each side, it’s better to lay a concrete shed base that is slightly larger than the dimensions of your shed.

Once you are happy with the area, you can start to remove vegetation and turf before digging out the topsoil. You’ll want to dig to a depth of at least 150mm, which gives you 75mm of depth for hardcore, and 75mm for your concrete shed base.

Keep compacting the ground, once hardcore is added you’ll need to compact it as much as possible to ensure a stable and level foundation for concrete to be poured on top.


Framing the area where you want to lay a concrete shed base will help the concrete maintain its shape while it sets. It’s best to make the frame out of timber, using the inside measurements of the frame to match the dimensions of your base.

Make sure the frame is level on top of the hardcore, and add pegs 600mm apart around the whole structure to keep it in place. The pegs will need to be below the top of the frame, to make it easier when levelling off the concrete shed base.

Pouring the Concrete

Readymix concrete for shed bases can be delivered direct to sites by local concrete companies. Make sure your pour site is ready for your delivery, and it’ll be done in no time.

Carefully pour the concrete in layers that fill the frame to the corners and edges. Spread the concrete and compact it using a tamping board to make sure there are no voids or bubbles, you can also tap the edges of the frame with a hammer to ensure any bubbles rise to the surface of each layer before you pour the next. Keep pouring layers until the concrete slightly overflows the top of the frame.

Once compacted via tamping, scrape off any excess concrete by starting at one end and working towards the other to leave a smooth and level finish, flush with the top of your frame.

Drying and Curing

Let the concrete set for at least three days before removing the frame. Depending on the weather, there are a few steps you can take to ensure the best finish.

  •       If it rains, cover up your new concrete shed base with plastic sheeting.
  •       If it’s very warm, use a damp cloth or spray the surface of the shedbase with a little water to stop it from drying too quickly.

Concrete shed bases continue to cure and reach their full strength after roughly 28 days, but it should be stable enough to build on after three to five days.

Adding your Shed

To allow air to circulate under your shed, build the shed on top of timber floor bearers. Making sure everything is level at every step may seem like an extra task, but it’ll help provide the most solid and reliable shedbase possible, meaning your shed will last longer and be easier to maintain for years to come.


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