If I understand correctly, when using a monolithic slab (where the footers and slab are poured as one piece), the vapor barrier is installed under the slab and the footers.
The NEC does not consider concrete that is over a vapor barrier to be in direct contact with the earth. ).
Are there any common practices or workarounds that are code compliant and used?
Note: I don't mean using a different grounding method, or skipping a vapor barrier. I'm asking if there's some clever way to get enough of the footer to contact the earth while still protecting the slab from moisture. Or something else along those lines.
NEC 250.52 (3)
Concrete-Encased Electrode. A concrete-encased electrode shall consist
of at least 20 ft of […] One or more bare or zinc galvanized or other
electrically conductive coated steel reinforcing bars or rods of not
less than 13 mm (1/2 in.) in diameter, installed in one continuous 20
ft length, or if in multiple pieces connected together by the usual
steel tie wires, exothermic welding, welding, or other effective means
to create a 20 ft or greater length.Metallic components shall be encased by at least 2 in of concrete and
shall be located horizontally within that portion of a concrete
foundation or footing that is in direct contact with the earth or
within vertical foundations or structural components or members that
are in direct contact with the earth. If multiple concrete-encased
electrodes are present at a building or structure, it shall be
permissible to bond only one into the grounding electrode system.Informational Note: Concrete installed with insulation, vapor barriers,
films or similar items separating the concrete from the earth is not
considered to be in "direct contact" with the earth.
Best Answer
Front Porch Grounding Electrode
An Ufer ground (concrete-encased electrode) can be made from any reinforced foundation or footing that is in direct contact with the earth, whether it is supporting a structure or not. This means that not only is the house foundation eligible provided it is in direct contact with the earth, but a front or back porch or stoop can be used in addition or instead provided it has a sufficient length of suitable rebar or wire inside and has a footing that is in direct contact with the earth. Since there's no need for a vapor barrier on a porch or stoop where the concrete's wearing surface is exposed to the elements anyway, this means that with perhaps a bit of trickery, you can get the benefits of an Ufer ground without having to give up a sub-slab vapor barrier for the main foundation and footings.