Concrete Slabs for Sheds - Steps 2 & 3

Step Two: Mark and Measure the Area for the Slab

Figure out precisely where your concrete flooring will be located. Mark out the exact area with string line and stakes. Use a measuring tape to get the exact measurements of the slab concrete that you will need. These measurements will be used to calculate the amount of concrete that you will need to order.

The steps for making this calculation are as follows:

  • Determine the area of the slab floor, which is measured as length times width.
  • Calculate the area in cubic metres. To do this, multiply the area in metres squared by the desired thickness of the floor in metres.
  • Example: If your shed concrete slab needs to measure 4 metres by 4 metres, its area is 16 metres squared. For a thickness of 200 mm, you need to multiple 16 by 0.2, which results in a total of 3.2 cubic metres.
  • Make sure to add an extra 10 percent to accommodate any errors or mishaps; in this case, you would multiply 3.2 cubic metres by 1.1 to arrive at a total of approximately 3.5 cubic metres, which is the total amount of concrete that you will need to mix or order.

Step Three: Create the Formwork for Your Concrete Pad

The next step in laying a concrete slab for your garden shed is creating the formwork that will support the wet concrete while it dries, sets and cures. The measurements that you made in the preceding step will come in handy here. First, make sure to have the right tools and supplies on hand. In terms of tools, you will need a hammer, timber pegs, a level, a measuring tape, digging tools and a carpenter’s square. In terms of materials, you will need timber that is the same height as the desired thickness of your concrete floor slabs. Based on our example above, two of the lengths of timber will need to measure four metres; the two other pieces will need to measure 4.2 or 4.8 metres in length. The end result needs to produce an internal measurement that adds up to the desired dimensions of the garden shed slab.

Once you have assembled the appropriate tools and supplies, place the pieces of timber in the right formation. Before you nail them together, use your carpenter’s square to ensure straight, true right angles. Position the completed framework precisely where you want to build a concrete slab. Mark the area so that you can see exactly where you will need to dig.