One of the most important parts of building a garage is pouring the concrete for the floor. A properly poured concrete floor provides strength and stability for the walls and roof of the garage. This can be a difficult and time-consuming task, but it is something that a do-it-yourself homeowner with the proper tools can complete.
Contact your local zoning board to get any permits that you'll need and learn the local building codes that you'll have to follow when pouring the floor.
Mark off the garage dimensions in the ground by driving stakes into the perimeter and tying them together with string.
Dig out the staked-out area with the excavator, making sure that you go below the frost line. Your local zoning board can tell you how deep the frost line goes.
Build a frame around the excavated pit by driving wooden stakes every three feet into the ground around the perimeter and nailing 2-inch-by-4-inch boards to them.
Cover the ground inside the framed-out area with a vapor barrier. This is a plastic sheet that prevents moisture from seeping up through the ground and damaging the floor.
Add a layer of sand or gravel on top of the vapor barrier. Follow your local building codes regarding the material that you need to use and how deep you need to make the layer.
Place rebar or wire mesh on top of the sand or gravel. Again, your local building codes can tell you which material you'll have to use and how you need to place them.
Mix up a batch of concrete in a concrete mixer, following the instructions on the packaging.
Pour the concrete into the framed-out area, filling it so that it goes a little bit higher than the frame.
Screed the floor with the help of a partner. Start at one end of the pour and rest the screed board on top of the frame. Pull the board across the pour with a side-to-side motion. This will smooth out the concrete and expose any low spots.
Add more concrete as necessary to any low spots and screed the surface again.
Slide a bull float over the concrete to smooth it out by pushing it across the surface with the back slightly tilted up, then pulling it back with the float flat on the concrete.
Cover the concrete with plastic sheathing. Keep the concrete damp for five to seven days, covering it back up with the plastic sheathing after you add water.
Allow the concrete to cure for about 4 days. Remove the frame around the floor.