Footings:
Normal footings should be 8-12" deep by 24" wide. When the land in use is not perfectly flat you must add "step downs" which are drops in the footing appearing as steps. At the end of the footing prior to the step down you should add a piece of plywood to stop the concrete from going any further. The step down should be 8" deep and 16" from the top of the upper footing to the bottom of the stepped down footing. The 8" step down is so the cmu blockwork will continue at a consistent run without having to fill in voids.
A normal imperfect lot may contain as many as 8 step downs then 8 step ups on the opposite side. A transit should be used when digging a footing and determining the proper locations for step downs in footings. A standard practice for steel rebar in footings for a residential application is double 5/8" rebar running continuous throughout the footing using bent pieces for corners and step downs. The rebar should be placed in standard "chairs" which hold the rebar off of the bottom of the footing. 5/8" all thread needs to be attached to the footing rebar every 6' to 8' depending on code of area and extending upwards past the point of the projected cmu foundation block height plus 8" .
Now you have a continuously tied in footing and all threads pointing up in the air to tie your structure to for uplift protection. Install grade stakes throughout the footing to assure that you have a continuously level concrete footing base. Don't forget the pier footings. The location is determined by a structural engineer or state licensed architect. The footings for them is basically the same as the home perimeter but without attaching to anything else and without vertical 5/8" all threads. The footing steel for the piers is a tic tac toe design using 5/8" rebar in chairs. Make sure that the footing height, also marked with grade stakes ends up being the same height as the perimeter footing or in increments of 8" up or down for adding cmu block to ensure a completely level footing ready for block. Pour the concrete to the grade stake height and smooth the concrete to a flat position. When the concrete dries you are ready to lay the foundation blocks.
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