Building a Concrete Base for your New Garden Shed Kit

Many of our customers ask us: What is the easiest way to create a base for my new garden shed kit? In other articles in our blog we have looked at ways to build a wooden base for your Duramax storage shed, but here we are going to look at the option of creating a concrete base. Essential items required are;                                             

  • 1)      2×4 timber & hand saw
  • 2)      4” nails or long screws (plus a screw gun)
  • 3)      Some fine stone aggregate (usually comes in bags)
  • 4)      A shovel and wheel barrow
  • 5)      Measuring type & Spirit level
  • 6)      A sheet of heavy plastic membrane
  • 7)      Sufficient quantity of concrete to fill base. 

Step 1: OK, so let’s get started. We are going to make our slab for a 10×8 shed. Allowing an extra 6” all around for stability, we will make base size 11×9. Next thing we are going to assemble a wooden template 11×9 for our footprint. So we cut 2 pieces of 2×4 at 11ft and 2 pieces at c.9ft.

Next we nail our template together at the 4 corners. When done we need to make sure it is completely square. The simple trick here is to measure diagonal corners both ways and when both corners are the same measurement then your template is perfectly square. To keep it square you might consider fixing a diagonal piece of wood temporarily. Now we are going places.

Step 2: OK, next you will place the template in position where your shed will finally rest. Now comes the hard work with that shovel and wheelbarrow. The idea is to excavate the top soil and grass only removing the exact area of your wooden template and no more. Excavation should be approximately 3-4” deep all round and the base should be as even as possible. Depending on the type of sub-soil you could consider using a garden rake to get the pre base nice and level. It will be best if you can have the finish floor level 1-2iches higher that the existing ground level.

Step 3: So now it is time to place our fine stone aggregate. This only has to be 1-1.5 inches deep and will allow drainage for any build-up of ground water later. It is important to get aggregate as smooth as possible before  placing a the layer of plastic membrane on top which will prevent any water soaking into your concrete slab.

Step 4: Before laying the concrete it will be necessary to fine tune levels on the wooden template. You will need the spirit level for this task and you will most likely need to pack the template at some corner with small stones or pieces of wood to get it level. It is important that it is sitting solid and stable when it comes to concrete stage. If there is any over excavated areas on the perimeter now would be the time to fill them in and compact earth against outsides of template so it can’t move around. Also take a final measurement on diagonals for square. You also could consider placing a layer of light reinforcing steel in the base at this stage which will make slab much stronger.

Step 5: Now the fun part. You will need to quantify your concrete needs and make sure you have enough to complete the job. You can mix it by hand or easier would be to hire a small mixer for the day at a minimal cost. After filling the base up with about 3” of concrete you will need to tamp and screed it off with a long piece of 2×4. This will be a 2 person job. Simply starting at one end, drag the piece of wood across the base levelling as you go. If you use a sawing motion it will leave a better finish. You will then need to trowel it off, which will bring  water to the surface. Leave it for c.1 hr and come back with a house brush and very gently drag brush across the surface, evenly, leaving what is called a brush finish. This helps leave a grip on the concrete when it is set and will be an ideal surface to place your new vinyl storage shed on. Bingo. Walk away…..:)

For more how to’s visit our blog at where your will find lots of usefull articles and tips on garden shed kits, vinyl storage sheds and brands like Suncast, Arrow and Duramax storage sheds.

8 thoughts on “Building a Concrete Base for your New Garden Shed Kit

  1. Pingback: Frei Klavier

  2. garden

    Hi There Gorman101,
    Speaking of which, I’m thinking of building a pretty sizeable shed in my garden. Mainly for storing wood. I was thinking of something about 12′ x 5′ x 5′ in size. Would I need to pour concrete foundations? and what materials should I use? I’m hoping to keep the costs relatively low but have something which will last.
    I’ll be back to read more next time

    1. gorman101 Post author

      HI there,
      It is ideal if you can install a concrete base. Check out our How to articles on this. Also check out our Rhino range they are an economical solution for what you are looking for.


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