Wire mesh supports

is what they call them around here. Find them at any steel supplier that has rebar or mesh, generally. Not usually found at home centers or lumber yards, more of a steel supplier.

Go with the continous rail bar chairs. They support mesh better than the single chairs, and don't sink into the foam insulation like the small ones. they come in a variety of sizes 1/2" increments usually 3 feet long.

Under mesh they need to be every 3-4 feet to do much good or the mesh just sags down between them. it takes more than you might expect to hold all that mesh up where you want it.

Tie the mesh, chair, and tube all together with the ties. this assures the tube stays up, the chair doesn't tip over, and the mesh stays in the pour without floating.

Keep in mind the chair dimension if you score the concrete with a cutter afterward!

Slabs do perform much better with the tube up in the middle as opposed to the bottom of the pour. it's worth the time to do this.

Stay away from rocks or bricks to hold mesh up :)

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