A carport is a simpler and less expensive alternative to building a garage. If all you want is to protect your car from the weather, a carport performs the same basic function. There are a variety of carport designs from which to choose, but no matter which plan you select, you need to first set down a solid foundation. A sturdy foundation will ensure that your carport stands strong in foul weather and that it will last for as long as possible.
Mark the area in which you plan to install the foundation for your carport by driving metal stakes into the ground at the corners and wrapping colored string all the way around the area between the stakes. To do this, you need to know the dimensions of the carport itself. You must add at least 4 inches to the width and 6 inches to the length so that you do not crack the concrete when anchoring the carport.
Dig out the foundation area to a depth of at least 4 inches. For large vehicles, a concrete foundation at least 6 inches thick is recommended. Dig the trench 2 inches deeper than the desired thickness of the concrete to accommodate a layer of compacted gravel.
Line the walls of the trench with 2-inch-thick boards to create a form for the concrete. Use metal stakes as necessary to hold the boards upright in place.
Compact the soil in the bottom of the trench using a hand tamper, and pour in a 2-inch layer of gravel. Use the hand tamper to compact the gravel, and use a level to ensure that the floor at the base of the trench is even.
Mix up a batch of 2500 psi concrete, according to the manufacturer's instructions. Psi stands for pounds per square inch. This simply refers to the weight the concrete can withstand without crushing. For large vehicles, you may choose to use 4000 psi concrete.
Pour some of the concrete into the trench, filling it a little less than halfway, spreading it with a rake as you go.
Lay down sheets of welded wire mesh inside the trench on top of the layer of concrete you just poured, positioning it as close to the center of the concrete thickness as possible. Welded wire mesh, which typically comes in sheets or rolls composed of 6-inch squares, will reinforce the concrete to prevent cracking. Position the welded wire mesh so there are at least 2 inches of space between the mesh and the wooden forms.
Pour the rest of the concrete to fill the trench. Use your rake to spread the concrete into and around the welded wire mesh.
Smooth the surface of the concrete using the rake or a screed, a tool specially designed to smooth concrete.
Use an edger to round the edges of the concrete slab around the perimeter.
Cover the concrete slab with a sheet of plastic, and allow it to cure for three to four days. Once the concrete has completely set, you can begin constructing your carport.