How Is ESD Flooring Tested and Certified to ANSI/ESD S20.20, and How Is It Grounded?
ESD flooring is certified under ANSI/ESD S20.20 as a system, not a material: the person, footwear, floor and grounding network are tested together. Two on-site tests decide it: system resistance per ANSI/ESD STM97.1 must be below 1.0x10^9 ohms, and peak body voltage per ANSI/ESD STM97.2 must stay under 100 volts while a person walks the floor in the facility's actual footwear; the material-only resistance on a data sheet (ANSI/ESD STM7.1) does not qualify the floor by itself. Yes, ESD flooring must be grounded: copper grounding strips are bonded to the conductive basecoat at the manufacturer's spacing (commonly a 24 by 24 inch grid in ESD epoxy) and terminated at building electrical ground by a qualified person, with continuity verified. Without that path the floor cannot discharge static regardless of its rating.
By Meera Sawhney · August 24, 2026 · 13
How is ESD flooring certified under ANSI/ESD S20.20?
An ESD floor specification can look complete while leaving out the details that decide whether the installed system works. A product data sheet may show a resistance value, but ANSI/ESD S20.20 does not qualify a bucket of resin or a finished floor sample in isolation. It evaluates the footwear and flooring system that a person actually uses in the protected area.
That distinction changes what belongs in the specification, what must be tested after installation, and what the facility team must protect during maintenance. This guide explains the two performance measurements, the grounding details that cannot be skipped, and the six items to put in an ESD flooring specification.
A resistance figure on a flooring product data sheet typically comes from ANSI/ESD STM7.1, which measures the flooring material by itself. That value can help compare materials, but it is not the same as the result of a person walking across the installed system.
ANSI/ESD S20.20 compliance is decided using the person, their footwear, and the floor together. The conductive or dissipative floor, grounding network, footwear, installation conditions, and cleaning program all affect the result. Specifying only a material number is one of the easiest ways to create a floor that looks compliant on paper but fails system verification in the room.
Which two tests decide whether an ESD floor passes?
Two different questions must be answered during verification. Both results matter:
- System resistance, per ANSI/ESD STM97.1: less than 1.0x10^9 ohms for the person plus footwear plus floor.
- Peak body voltage, per ANSI/ESD STM97.2: under 100 volts while the person moves across the system.
Resistance describes how readily charge can leave the person through the footwear and floor. Body voltage describes how much charge the complete combination generates while walking. A floor can perform well on one measurement and still miss the other, so a supplier certificate for the material alone cannot replace on-site verification with the facility's actual footwear.
How is floor resistance measured on site?
Conductivity is measured, not claimed. A floor's static behavior is defined by electrical resistance - and that's measurable, which is what makes it specifiable and auditable. Compliance starts with the ESD control plan stating the required range. "Conductive flooring" without a stated target and test isn't compliance - it's a description.
Compliance is demonstrated, not assumed:
- Installed to ANSI/ESD S20.20 - the control-program standard.
- Tested to ANSI/ESD STM7.1 - floor-material resistance measured across the finished floor with a concentric ring electrode, including resistance to ground as specified in the test plan.
- Documented - results retained for the compliance file at defined test locations and environmental conditions.
STM7.1 measures the floor material's resistance, including its resistance to ground; it does not test the person-footwear-floor combination. STM97.1 measures that combination's system resistance, and STM97.2 measures walking body voltage. Run the system tests with the facility's actual footwear before the room is released.
This is the deliverable an auditor wants. Why documentation matters: why regulators care about lab flooring.
Should I specify conductive or dissipative?
Conductive and dissipative describe resistance bands, not a ranking where lower is always better:
- Conductive: resistance to ground of 1.0x10^6 ohms or less.
- Dissipative: above 1.0x10^6 ohms and below 1.0x10^9 ohms.
| Category | Surface resistance | Typical cleanroom use |
|---|---|---|
| Dissipative (ESD) | Above 1.0x10^6 and below 1.0x10^9 ohms | Standard for most electronics and lab cleanrooms |
| Conductive | 1.0x10^6 ohms or less | Most sensitive processes or explosive atmospheres |
The hazard assessment determines the selected band. For explosive or flammable environments, the conductive range has a typical lower bound of 2.5x10^4 ohms. Component sensitivity and the presence of flammable materials are part of that assessment.
Faster charge drainage is not automatically the right choice for every operator or every zone. A lower-resistance path across a person near exposed line voltage introduces a shock-hazard question that belongs in the facility's hazard assessment. Many electronics environments select a dissipative band for that reason. Record the reasoning for the selected band in the design documents so the choice can be checked during future audits or process changes.
See Common mistakes to avoid in the complete anti-static flooring guide: over-specifying conductive when dissipative meets the plan, skipping post-installation testing and documentation, and ignoring substrate moisture and preparation.
Does ESD flooring need to be grounded, and how is that done?
The floor can only perform as designed when the grounding path is continuous. The specification should identify the manufacturer's required copper grounding-strip spacing, how the strips bond to the conductive layer, the conductive primer or adhesive system, and where the connection terminates at building ground.
Ground termination must be completed and documented by someone qualified to make that connection. A break in the strip layout, a missed bond, an incompatible adhesive, or an incomplete termination can leave an area that cannot drain. The problem may not appear at a test point elsewhere in the room, which is why the grounding layout and verification plan should cover the whole protected area.
A conductive or dissipative floor only complies if charge has somewhere to go. The system needs a continuous conductive plane (conductive basecoat), the resistance-setting surface (topcoat), and copper ground straps to earth ground with verified continuity. An ungrounded "conductive" floor measures resistance but provides no path to ground - which fails the intent of the standard. See anti-static flooring solutions.
For ESD epoxy, copper grounding strips are commonly laid as a 24 by 24 inch grid embedded in and bonded to the conductive basecoat. This is typical spacing, not a universal requirement: confirm the manufacturer's required layout, bonding method, and conductive primer or adhesive. The network terminates at building electrical ground through a qualified person, with continuity verified.
Ground straps are installed before the system application. For the sequence and layer roles, see The system, layer by layer in the complete anti-static flooring guide and its Installation, step by step section. That guide remains a separate reference rather than being folded into this specification page.
How does a cleanroom floor meet both ISO classification and ESD requirements?
In a cleanroom that handles static-sensitive product, two standards systems meet on the same floor: the cleanroom classification that governs particles, and the ESD control plan that governs static. Conductivity flooring is how you satisfy the second without compromising the first. The electrical performance must be proven alongside the contamination-control requirements.
The short version: "conductivity flooring" controls how readily charge moves through the floor to ground. Compliance means hitting a defined resistance range (dissipative or conductive), grounding the system, and verifying it by test - while keeping the floor cleanroom-compatible (seamless, low-outgassing, coved). All four conditions, together.
The electrical requirements can't override the cleanroom ones. A compliant cleanroom conductivity floor is simultaneously:
- Seamless and monolithic - no contamination traps.
- Low-outgassing - no volatile compounds into controlled air.
- Coved at the base - cleanable to the wall.
- Classification-appropriate - materials compatible with the ISO class.
DTI installs ESD systems compatible with ISO cleanroom classifications - low-outgassing, seamless, and verified to resistance spec - which is exactly this dual-compliance requirement satisfied in one system. See cleanroom flooring for electronics.
Five-item cleanroom compliance checklist
- Resistance target stated by the ESD control plan (dissipative or conductive)
- Grounded with copper straps; continuity verified
- Tested to ANSI/ESD STM7.1; results documented
- Seamless, low-outgassing, coved, classification-compatible
- Maintained so resistance holds over time
One floor can meet both sets of requirements: a seamless, low-outgassing, coved ESD system compatible with the ISO class supports particle and static compliance together. Document the floor-material tests and the person-footwear-floor system verification; the material resistance reading alone is not the completed S20.20 system qualification.
What can turn off a compliant ESD floor after installation?
ESD performance is a maintenance condition, not a permanent visual feature. A clear acrylic floor finish applied later by a maintenance crew can act as an insulating layer over the conductive surface. The floor may still look clean and intact while the electrical path is blocked.
Silicone and oil contamination, unapproved cleaning chemistry, a change in site footwear, damaged grounding connections, and seasonal humidity changes can also move the system result. The handover package should state what products and footwear are approved, what must not be applied, and who is responsible for re-verification after a change.
Facilities with cleanroom or data-center requirements should coordinate the flooring maintenance plan with their existing contamination, access, and equipment-protection procedures. An ESD floor that is maintained outside the facility's broader program will eventually be tested under conditions it was never specified to handle.
List approved cleaning products and footwear, prohibitions on insulating finishes, responsibility for re-verification, and the re-verification interval in the handover package.
What are the six items an ESD flooring specification must include?
A useful specification makes the performance requirement testable and assigns responsibility for the details. Include these six items:
- Reference the governing standard and test method. Reference ANSI/ESD S20.20 and require system verification per STM97.1 and STM97.2 using the facility's actual footwear, not only a supplier's material sample or certificate.
- State the resistance band and the reason for it. Identify conductive or dissipative performance for each zone, and record the shock-hazard reasoning from the facility's hazard assessment.
- Detail the grounding network. Show strip layout, spacing, bonding method, conductive layer requirements, termination location, and the party responsible for making and documenting the building-ground connection.
- Require post-installation verification on site. Define the test locations, equipment, environmental conditions, footwear, acceptance criteria, and report that must be delivered before the area is released.
- Protect the finish during handover. Put the no-acrylic-finish restriction and approved cleaning chemistry in the handover documents, maintenance instructions, and signage for the protected space.
- Set a re-verification interval. State how often the floor and footwear system will be checked, and require a new review after a change to footwear, cleaning products, floor finish, grounding, process, or room use.
What should be verified before the room is released?
Post-installation testing should be planned before the flooring work begins. The verification record should identify the zones tested, the footwear used, the test method, the test conditions, and the measured results. It should also document any locations that were repaired or retested.
Walk the room with the facility team after testing. Confirm that grounding points are accessible, transitions are protected, the maintenance restrictions are understood, and the approved footwear is available. This handover is where the installed ESD flooring system becomes part of the facility's operating program instead of remaining a contractor deliverable.
From our jobs
Project example coming soon
For an existing documented example, DTI's data-center ESD flooring guide describes a Silicon Valley facility with an ESD polished-concrete floor plate grounded and resistance-tested to the owner's acceptance criteria. The reported example concerns grounding and resistance verification; it does not publish footwear-system resistance or walking-body-voltage results. No STM97.1 or STM97.2 pass result is inferred from that description.
Specify the system, then protect the result
An ESD floor is not qualified by a resin label or a single resistance number. The system must be designed around the zone hazard, grounded continuously, verified with the facility's actual footwear, and maintained without insulating finishes or unapproved cleaning products.
DTI installs and verifies static-control flooring for manufacturing, electronics, laboratory, and process environments nationwide. Book a floor-condition assessment to review an existing ESD floor or discuss the performance requirements for a new specification.
For a cleanroom with both particle and static requirements, DTI installs and test-documents conductivity flooring to your classification and control plan. Request a consultation or call (209) 879-9674.
Related reading: why regulators care about lab flooring, cleanroom flooring for electronics, and anti-static flooring: the complete guide.
Frequently Asked Questions
How is ESD flooring tested and certified to ANSI/ESD S20.20?
As a system, with the facility's actual footwear. System resistance per ANSI/ESD STM97.1 must be below 1.0x10^9 ohms and peak body voltage per ANSI/ESD STM97.2 must stay under 100 volts while a person walks the floor. The material-only reading on a data sheet, from ANSI/ESD STM7.1, does not qualify the floor alone.
Does ESD flooring need to be grounded?
Yes. The floor only works if charge has a continuous path to building ground. An ungrounded ESD coating provides no protection regardless of its rated resistance. The grounding network, its bonding to the conductive layer and its termination at electrical ground all have to be specified, installed by a qualified person and verified.
How is ESD flooring grounded?
Copper grounding strips are bonded to the conductive basecoat at the manufacturer's required spacing, commonly a 24 by 24 inch grid in ESD epoxy, using a conductive primer or adhesive. The strips terminate at building electrical ground and continuity is verified. A break in the strip layout or a missed bond leaves zones that cannot drain.
What resistance range should an ESD floor have?
It comes from the hazard assessment. Dissipative floors measure above 1.0x10^6 and below 1.0x10^9 ohms and suit most electronics manufacturing. Conductive floors measure 1.0x10^6 ohms or less, with a typical lower bound of 2.5x10^4 ohms, and are used for explosive or flammable environments. Faster discharge is not automatically better.
How is floor resistance measured after installation?
Resistance is measured across the finished floor with a concentric ring electrode per ANSI/ESD STM7.1, at defined test locations and environmental conditions, and the results are documented for the compliance file. System tests per STM97.1 and STM97.2 are then run with the facility's footwear before the room is released.
What can make a compliant ESD floor stop working?
A clear acrylic finish applied later insulates the surface while the floor still looks intact. Silicone or oil contamination, unapproved cleaning chemicals, a change in site footwear, damaged grounding connections and seasonal humidity shifts also break compliance. The handover package should list approved products and footwear and set a re-verification interval.