Harold:
This is a tough one IMHO. Conflicting 'he said/she said', and a gray area within the NEC.
There are differing opinions on the conductivity of wood, which I don't want to debate, although someone will. Composite decking is also a debate by some.
Opinions that I have heard range from the absurd (IMHO) of 'bonding the wood' to ....nothing.
Most spas that I have seen install the rubber type listed mats under and around the spa; case closed.
Installs on existing concrete or paver patios are another tough call. Bonding the existing rebar/mesh is one option, the pads is another, or the grid around the slab. Problems arise when the 'slab' is a large patio. Solutions range from finding the rebar/mesh to saw cuts & #8, or..the pads.
Welcome to confusion!!
