Area of garage foundation
You need to demarcate the area where you are planning to make the garage foundation. Get a can and place lime in it. Then pour out the lime around the perimeter of the garage foundation.
Take out the dirt from the area where you are building the garage foundation. Use a shovel to dig the footings and it should be 18 inches deep and 1 foot wide. You should dig extra few inches for sand and vapour barrier purposes. Remember to follow local building codes while making the garage foundation.
Place the form boards
First take 2 by 10 form boards and pour concrete in it. You need to build the outside around six inches higher than the height of slab. This will make a concrete curb on the perimeter of the garage.
Then take 2 by 6 form boards and place it inside the form board.
Next you need to place ½ inch rebar on the bottom of all the footings. Remember to place it around three inches away from bottom and the sides. Same should be the case when you place rebar on the top i.e. it should be away three inches from air and sides.
In order to hold the sill plates, you need to place the foundation bolts. You need to use a diesel fuel or a chemical so that concrete won’t stick to wood.
Next pour sand into the area where you are going to place sand. This is to prevent moisture from entering through the slabs.
In the end you need to pour concrete into the footings. After waiting for few hours, pour the garage slab.