Concrete-Encased Electrode Tests on Commercial and Multifamily Foundations, Austin Area and Fort Worth (2021-2026)

Bigger slabs raise the same question as a house: is the steel in the concrete bonded to the electrical system, and is the grounding electrode system good enough? From 2021 to 2026 we ran concrete-encased electrode (Ufer) tests on eight commercial and multifamily structures in Austin, Lakeway, Del Valle and Fort Worth.

The structures

They included the parking garage of an apartment complex, several multifamily buildings, a group of multifamily dwellings tested together, commercial buildings in Lakeway and Austin, and in 2026 a residential structure in Fort Worth tested at an early stage of construction. The method matches our residential work. A tone sent into the slab reinforcing steel from the panel ground or the Ufer is traced across the slab, a three-pole fall-of-potential test measures resistance to remote earth, and any ground rods are found and tested.

Results worth noting

The parking garage, tested in January 2021, had a ground rod at 4.03 ohms, and the slab measured 0.85 and 0.78 ohm at two points. A commercial building in Lakeway, tested in December 2021, showed why both electrodes get tested: its Ufer measured 2.18 ohms, but its ground rod read 96.7 ohms, far above the 25 ohm value in the code. For one 2022 multifamily site the slab measured 1.93 ohms and no rod was present, so the task was to install a ground rod to supplement the Ufer. Another 2022 commercial building passed on its two ground rods at 2.03 ohms, and the tone reached every part of the slab at 2.05 ohms, yet the Ufer connection itself did not meet the code, and the report called for a new one.

A concrete electrode cannot stand alone

At a multifamily building tested in 2026 we found no ground rods at all, and the slab measured 39.0 ohms to remote earth. The report states the limit of what testing can show: once poured, a concrete-encased electrode cannot be examined, and no fall-of-potential or resistance test proves the long-term stability of steel in concrete as the only grounding electrode. The Fort Worth structure, tested in 2026, measured 0.87 ohm through its slab steel.

Related services

Fall-of-potential testing and the rest of our field methods are described under grounding system tests.