New concrete slabs and old concrete slabs fail coatings for different reasons, so the preparation and testing scope has to be built around the slab's actual history, not a generic checklist. A new slab is mainly a question of cure time, residual moisture, and whether a curing compound is present; an old slab is mainly a question of contamination, prior coatings, and physical wear. This guide is written for the facility manager, property manager, general contractor, or building owner who is deciding what to put in a scope of work, not for the crew doing the grinding or shot-blasting. It walks through how cure age and moisture testing differ for new concrete, what to look for on an older slab, how cracks and joints get handled, what tests to ask for before you accept a bid, and how the written scope should be worded so expectations match what the contractor actually delivers. For a side-by-side look at the mechanical and chemical prep methods themselves, see Concrete Surface Prep Methods Compared.
Manufacturers set their own minimum cure age before a coating or primer goes down, and the numbers vary by product line. Tnemec's data sheet for its Series 208 Epoxoprime MVT lists a minimum of 10 days of cure at 75°F before application, while the same manufacturer's conventional Series 201 and 215 products call for 28 days. Tnemec's Series 281 data sheet specifies a minimum of 28 days of cure at 75°F, and Sika's Pronto RB-1855 CP MMA system data sheet requires floors to be structurally sound and fully cured a minimum of 28 days. Stonhard's Stonclad UT cementitious polyurethane mortar can go over new or green concrete in place at least 5 days. Because these numbers come from different product categories, confirm the figure on the specific data sheet for the system being quoted rather than assuming one number applies across the job.
Sherwin-Williams' technical literature describes 28 days as the industry standard for curing concrete but notes that this is not always sufficient time for excess moisture to leave the slab, which can create problems with non-permeable flooring; moisture testing is recommended regardless of age. Tnemec's guidance for its Series 201 and 215 primers makes the same point directly: even after 28 days at 75°F, dryness still has to be verified by relative humidity or moisture vapor emission rate testing. ASTM F1869 states that all concrete subfloors emit some amount of moisture in vapor form, and that any single reading only reflects the condition of the floor at the time of the test. In practice this means the cure-age clock and the moisture test are two separate questions, and both should appear in the scope.
Ask whether a curing compound was applied; whether it must be removed is set by the coating manufacturer's data sheet. The manufacturer's data sheet and the actual jobsite conditions on that day govern what prep and timing are appropriate, more than any general rule. For a deeper look at moisture-specific testing and mitigation choices, see Moisture Mitigation for Colorado Slabs.
Old slabs bring a different set of questions. Instead of asking "how long has it cured," the contractor needs to establish what is on and in the slab already.
The written scope should state how existing cracks and joints will be treated; the treatment depends on the coating manufacturer's instructions. The written scope should specify:
Testing requirements differ for new and old slabs, but both need documented results before a coating system is chosen — not after.
| Test or practice | What it covers |
|---|---|
| ASTM F2170 | Quantitative determination of percent relative humidity inside the slab using in situ probes; results reflect only the time and locations tested |
| ASTM F1869 | Quantitative determination of moisture vapor emission rate from bare concrete, expressed as pounds per 1,000 ft2 over 24 hours; does not apply over coatings, penetrants, or patching compounds |
| Surface pH testing | Per Sherwin-Williams Form G-1, pH is tested on the prepared floor; normal concrete is 11-13 and a reading of 10 or lower calls for additional preparation. Other manufacturers' thresholds may differ. |
| ASTM F710 | A practice describing that all slabs should be tested for moisture regardless of age or grade and tested for pH, and that a permanent vapor retarder is required under on- or below-grade floors; written for resilient flooring, not coatings |
For a new slab, sequence depends on the product data sheet: some checks (e.g., Sika surface meter reading, pH) are run on the prepared surface, while F1869 requires bare concrete; the scope should state the order.
For an old slab, the sequence starts with identifying and removing prior coatings or contaminants, testing pH on the freshly prepared surface, and addressing cracks and joints; the scope should state which moisture and strength tests are required by the coating manufacturer for the existing slab.
Profiling itself — the physical roughening of the surface to the degree a coating needs — is described separately in Concrete Surface Prep Methods Compared. Ask contractors how profiling, moisture assessment, and repair work will be scoped and coordinated with the coating schedule. See concrete surface preparation in Colorado and commercial epoxy flooring in Colorado.
A written scope or quote should spell out, in plain language:
Costs for this work vary by scope, slab condition, and location; the concrete surface preparation cost guide for Colorado and the cost calculator can help frame budget expectations before bids come in.
Not necessarily less, just different preparation. pH testing applies to both, with new slabs mainly needing cure-age, moisture, and strength checks and old slabs also needing contamination and prior-coating assessment. Both require documented testing before a coating system is specified.
Not automatically. Sherwin-Williams' literature describes 28 days as the industry standard cure period but states this is not always enough time for excess moisture to leave the slab, and recommends moisture testing regardless of age. Tnemec's data sheets for its Series 201 and 215 products make the same point, requiring RH or moisture vapor emission testing even after 28 days of cure.
Moisture tests measure RH inside the slab (F2170) or vapor emission from bare concrete (F1869), while pH testing checks surface alkalinity after preparation. Sherwin-Williams notes that a prepared floor testing at pH 10 or lower needs additional preparation to achieve a good bond, since contaminants tend to be neutral to acidic. A slab can pass one test and still need attention on the other.
ASTM F2170 states results reflect only the time of the test and the locations tested, and F1869 states its result reflects only the time of the test. Whether and when to test a new slab follows the coating manufacturer's data sheet. Confirm with the contractor when testing will occur relative to HVAC operation and coating application.
The coating or primer manufacturer's data sheet sets the specific moisture, pH, and strength requirements for that product, and those figures vary between manufacturers and product lines. Ask your contractor to show you the data sheet for the exact system being proposed and confirm the test methods and thresholds in writing before work begins.
How diamond grinding, shot blasting, scarifying, and acid etching compare for commercial concrete prep, with the surface profiles each produces.
How concrete moisture is tested: in-situ RH probes, calcium chloride, and plastic sheet tests, what each reports, and when results are meaningful.
How moisture mitigation systems work on slab-on-grade concrete, when a coating project needs one, and what to put in the written scope.
FloorSpec matches commercial flooring projects to contractors whose service areas and service types fit the work. We review each contractor's credentials, insurance, and licensing. We do not verify a contractor's track record with a specific facility type, so ask about relevant experience during your own evaluation. FloorSpec is free for project owners.
Two-minute form. One reviewed contractor. Free for project owners.