Depending on the layout configuration the reinforcing bars can be placed in two layers one mat or four layers two mats at both the top and bottom.
Double mat rebar.
Multi level rebar chairs.
The latter are easier for novices to use but somewhat more expensive the former is often the choice of experience rebar tiers rodbusters.
When used with sand plate.
Most times rebar is tied with annealed steel wire either bought in four pound bulk rolls or if using a bag tie spinner in bundles of precut wire pieces with loops formed on both ends.
Multi level chairs are used on mats or other configurations that involve multiple layers of steel the multi level chairs can be placed at multiple heights allowing you to install a bottom layer an intermediate layer and a top layer maintaining proper spacing between all of the rebar layers.
For very thick mats.
Standard concrete gray color custom colors available inquire minimal surface contact designed for maximum aggregate flow and concrete consolidation.
Single mat rebar or wire mesh bottom layer double mat rebar or wire mesh tilt wall side form spacer on grade.
Reinforcing bars need to be precisely and accurately located to adhere to design specifications.
Choose the method you will use to tie the rebar.
Haala industries offers a complete line of prefabricated and preformed rebar reinforcement mats including base mats centered and eccentric cover mats box culvert reinforcement pib mats con frame and catch basin mats.
Per code section 7 12 2 2 the bar spacing.