One complication of this method is efficient drainage
ACT 302 recommends subbase material be compactible, easy to trim, granular fill that will remain stable and support construction traffic. 3/4' gravel is often used for subbase and it is cost effective and usually readily available. The minimum thickness is 4' and is often much thicker.
Build the concrete forms with lumber such as 2x2, 2x6, 2x8, or 2x10 and double up or stack as necessary for cement slabs with thickened edges. Place supports every four to six feet on the outside of the forms to prevent the concrete from blowing out the planks. This can be achieved by using 2x4 stakes pounded into the ground flush with the form, backfilled with gravel or earth, or supported by nearby structures such as trees. Use a level or transit to level the forms at the desired elevation.
Install foundation foam if appropriate. This is typically 2.5' styrofoam in 2' x 8' size.
Install vapor barrier over the foundation foam.
Install rebar as required. This is often installed with two rows within the thickened area of the slab and held in place by tying to shorter rebar that are used as stakes.
Install #10 wire mesh if appropriate. The wire mesh comes in 6' x 6' sections and should overlap by at least 6'. The wire mesh can sit on special 'chairs' that are available from the local build materials supplier for a nominal fee.
When the concrete truck arrive pour the back of the slab first and work forward starting at the perimeter. Pour a wheelbarrow's worth of concrete every eight feet from the edges of the slab. Level this patch of concrete using the transit or other level. This is now the reference and an 8' length of 2x4 can be used to level the concrete between the patch and the edges of the slab. It is easier to attach two handles (strapping or other small wood) on the edge of the 2x4 in the center about two feet apart. Use the handles to pull the 2x4 to you while scapping off excess concrete to get the level correct. Repeat as necessary to complete the rest of the cement slab.
Use a bull float or a fresno trowel to level and smooth the concrete.
Use a concrete trowel to level and smooth the edges of the cement slab.
Use a concrete machine trowel to machine polish the slab once the concrete is hard enough to support the weight.
Allow the concrete a day to cure and then strip the form and backfill as necessary.
Learning how to build a cement slab is a great experience and a perfect opportunity to bond with friends over a few beer while exploiting their labor to save thousand of dollars, which is a great way to start building a garage or shed.