This method of building a pier and beam foundation can be used with any shed, barn, or other unoccupied structure. With a pier and beam foundation, there is a built-in crawl space under the structure.
Note: Any foundation built for an occupied structure such as a home or garage must be designed by a qualified profession. Permits and inspections must be obtained from your local jurisdiction to construct such a structure.
Establish the location where your building will sit. It is essential that you know where the outline of your structure will be so that you can know where to put the piers for the pier and beam setup. Starting at one corner, you will allocate a spot every 36 inches along the outer perimeter of the structure for your piers.
At each pier location, you will need to dig a hole using the post hole diggers. Minimum depth in warm climates should be at least 18 inches. For a sturdier foundation, or in cool climates, holes must be deeper than the frost line-- generally 40-48".
Once the hole is complete, you will put in the concrete cinder blocks or other concrete blocks that you have acquired for this project. If the blocks require stacking to reach above the previously dug hole, then you can stack them on top of one another. You want to ensure that the first cinder block is at least 18 to 24 inches above the ground. No mortar is required because the weight of the building will keep them in place. Note: The size of the piers is also dependent on the size of the structure you are building.
Make sure that the pier is level vertically, using the plumb line or vertical level. Fill in the holes with small rocks first at the base, tamping them in if possible with a long stick or the end of a broom handle. Then back fill the dirt into the hole that originally came out of the hole. Be sure and tamp down this as well using your foot or other flat surface such as a board remnant.
Continue to install the pier system along the outer perimeter of your structure at the set intervals. Each one should be checked before back filling the hole to ensure they are level with the previously installed piers. This is done using the string level along the top of the concrete blocks. After you complete the perimeter, you construct the pier system for the inside of the structure in the same manner, but spacing out the piers as much as four feet apart, along the floor joist intervals (recommended at 24 inches).
Add the 2 by 6-inch lumber selected for this project as your floor joist/beam setup. These beams will lay on edge and be nailed to form a connected beam foundation around the perimeter of the structure. In addition, at the 24-inch intervals, they will be laid out across the structure and nailed in place, resting on the internal piers already established.