Start by marking the coping with chalk or soapstone at 1-foot intervals.  For skatepark construction, use number three (3/8-inch) rebar set on one foot centers.  There will be a maximum of 12 inches from the center of one piece of rebar to the center of the next piece in all directions.  Number three rebar is very malleable.  Start by lightly bending some pieces of rebar and welding them vertically to the back of the coping at the marked locations.  Do not allow the rebar to stick up above the coping or it will poke out of the concrete when the deck is poured.  Be aware that rebar is made from recycled steel that does not provide for the strongest weld and also has a tendency to rust quickly.  Prepare the coping and the rebar as per any welding operation by cleaning the material down to bare metal.  Continue to attach vertical rebar until the entire bowl is finished.  It is unlikely that one piece of rebar will complete a span from one side of any obstacle to the other.  In that case tie on additional sections of rebar until each vertical piece of rebar goes across to connect with another piece on the opposite side. Any two pieces of rebar being tied together must overlap by 30 times the diameter of the rebar or approximately 16 inches. 

Tie the rebar with standard tie wire or use any other commercially available tying system designed for that purpose such as quick ties.  The quick tie system consists of pre-cut wires with loops at each end.  The wire is wrapped around the pieces of rebar to be tied together and a tool consisting of a small hook that swivels at the end of a wooden handle is placed within the loops and twisted, tightening the wire.  This is the quickest and most efficient method of tying rebar and is the easiest for unskilled volunteers to learn to use correctly. 

Starting at the coping, tie pieces of rebar horizontally to the vertical rebar that is already in place.  Remember to place it on one-foot centers.  Anywhere that the rebar overlaps must be tied as well.  Anytime you need to continue a horizontal or vertical run the two sticks of rebar must overlap by at least 16 inches. 

It is easiest to make some measuring guides one foot in length out of scrap rebar so that everyone can have one to use.  Rebar can be cut with a hacksaw, but this is slow going.  For a large job like a skatepark, use a rebar cutter.  They can be rented by the day or week at most equipment rental locations.  Always leave a 2 inch space between the rebar and the inside edges of all forms.  Before pouring concrete raise the rebar 2 inches above the ground with rocks or pieces of broken concrete block so that the rebar will be in the center of the finished slab.  Make sure measurements are accurate and that everything is tied up well.  It is more than likely that an inspector from the city will be by to examine your work before pouring and he or she will check ties.

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