A polished concrete floor lives or dies by its specification. A vague finish clause such as smooth polished concrete leaves gloss, profile, slip resistance and defect limits open to interpretation, and disputes settle toward whoever can show a written standard. This article walks a spec writer through the Division 03 structure: base slab obligations, quantifiable finish metrics, mock-up requirements, submittals and test methods, and clauses that prevent later argument. Figures follow accepted ranges; the project spec may set tighter limits.

Where polished concrete sits in Division 03

Polished concrete is usually specified under Division 03 Concrete, linked to the structural slab in 03 30 00 Cast-in-Place Concrete and the floor finish in a polishing subsection. State which party controls the base slab: slab flatness, moisture, curing and joint layout are slab contractor scope; grinding, densifier, resin polish and sealer are polishing scope. Cross-reference the slab tolerance clause and do not let the polish spec absorb base-slab defects.

Scope, base slab conditions and exclusions to state up front

List what the polish contract covers and what it excludes: existing slab strength and flatness, topping repair, crack injection, joint sealing, wall and column edge work, and traffic protection during curing. State the base slab condition accepted for polishing: sound concrete, no standing water, joints cut, prior topping or adhesive removed. Exclusions keep the polish contractor from taking on slab remediation that belongs elsewhere.

Quantifiable finish metrics: grit, profile, gloss and slip

Replace adjectives with measurable targets. Specify the grit sequence, target profile and finish class: CSP 3-4 standard medium grind, CSP 1-2 heavy aggregate exposure, CSP 5-7 near-mirror. Name metal grits 16/20/30/40 and resin pads 100/200/400/800/1500/3000. Gloss is measured at 60°; adjacent areas may differ by 5 gloss units, over 15 units needs rework. Slip resistance: dry PTV at least 36, wet PTV 10-20 points lower, DCOF at least 0.42; wet zones grade R10-R12.

Mock-up and sample panel requirements

Require a mock-up panel before full production: agreed size, for example 3×3 m, on the actual base slab or a representative pour. The mock-up fixes grit sequence, profile, gloss, aggregate exposure, edge treatment and joint appearance, and serves as the acceptance reference for the whole floor. Specify who approves it, how long it stays protected, and whether production panels must match it point by point or within the gloss and profile tolerances above.

Submittals, testing and acceptance criteria

List submittals the contractor must provide: product data for densifier and sealer, grit sequence, sample labels, and test records for RH, gloss, PTV/DCOF and flatness. State test frequency: gloss and profile checks per grid bay, slip tests at entry, wet zones and ramps, RH tests at agreed intervals before chemical phases. Acceptance is against the mock-up and the stated numbers; a clause that lets the owner reject on subjective appearance alone invites dispute.

Schedule, moisture and curing obligations

Put moisture and curing timing in the spec rather than leaving it to the crew. The slab must reach the agreed age and RH before grinding; ambient RH stays below 75-80% and surface temperature 10-30 C during densifier and sealer. Densifier dwell and sealer cure times follow the product data sheet; protected traffic and heavy loading wait until cure completes. Note recoat cycle: protectant or sealer renewed every 3-5 years, high-traffic zones every 2-3 years, so the owner budgets maintenance.

Common dispute clauses and how to word them defensibly

Disputes usually trace to clauses that are either silent or subjective. State who owns base-slab flatness, moisture and cracks; define rework triggers by measured numbers, not looks rough; say whether low spots are ground, filled or rejected; and record who signs each phase. Avoid open-ended best quality language and clauses that require matching an unrelated reference floor.

• Separate slab contractor scope from polish scope in two clear clauses.
• Tie every finish requirement to a number, a test method and an acceptance limit.
• Name the mock-up as the visual reference and list what it does not govern.
• State rework responsibility: grinding, topping, sealant or slab replacement.
• Record approval sign-off per phase so later rejections have a baseline.

Spec review checklist before issue

Before issuing, check that every metric has a target, a method and a limit; that mock-up approval, submittals and test frequency are named; that exclusions and party responsibilities are explicit; and that no clause delegates finish judgment to subjective taste. Keep the spec consistent with the drawings, slab mix design and the intended traffic class. A defensible spec does not over-specify; it makes the finish measurable before the first shoe touches the slab. The writer who records tolerance, method and limit up front avoids most post-completion arguments, and gives the contractor a clear scope to price and the owner a standard to enforce against.