http://www.homebuildingandrepairs.com... Click on this link for more information about patios, walkways and concrete building foundations. This video will provide you with a couple math formulas that will provide you with stepbystep instructions on how to figure out where to locate control joints in a concrete slab, patio, walkway, driveway or large building. It will also provide you with a simple formula for the depth of these cuts also. Don't forget to watch more of these helpful videos and increase your knowledge about construction.