Is a quick reading with a handheld concrete meter enough?

Only if your floor's maker accepts it. Wagner says surface meters read about the top half inch and fall under ASTM F2659, a guide for preliminary checks, not the F2170 RH test. Provenza does list a Tramex meter reading of 4.5 as one acceptable method; for concrete, Pergo's instructions name only the calcium chloride and RH tests.

The RH probe came back at 78%. Did the slab pass?

It depends on whose floor you bought. Pergo's locking engineered floor accepts anything under 80% RH by ASTM F2170, so 78% passes. Provenza caps the same test at 75%, so 78% fails and needs a moisture-control product or more drying. That's why the maker and product belong on the quote before testing.

How long should the AC run before anyone tests the concrete?

At least two weeks for Pergo, whose instructions want the HVAC operating 14 days before moisture tests or installation. After that, F2170 probes need 24 hours in the slab before a reading counts, under the 2018 revision Wagner describes. A calcium chloride test adds 60 to 72 hours on top.

If the slab tests dry in winter, can it turn wet by summer?

Yes. Provenza's instructions say in capitals that a slab that tests dry can still become wet at other times of year, and that the tests don't guarantee a dry slab. An NWFA magazine article adds that every on-grade slab holds moisture and always will, which is why engineered planks are the safer choice on concrete.

How many test holes will an RH test put in my floor?

Three in the first 1,000 square feet and one more for each additional 1,000, by Wagner's reading of ASTM F2170. Each is a small drilled hole at 40% of the slab's depth, patched once the reading is taken. A 2,000 sq ft slab would get four. Calcium chloride tests sit on the surface instead.

Concrete Moisture Testing in Pompano Beach, FL

Typical cost: no national guide prices the service; Wagner, a meter maker, puts materials at about $11 per calcium chloride test and $37 per RH probe.
Time: an ASTM F2170 RH probe reads after 24 hours; a calcium chloride dome sits 60 to 72 hours (Wagner).
Pass mark: set by the floor's maker, e.g. 75% RH for Provenza and under 80% for Pergo's locking engineered floor.
Before testing: Pergo wants the HVAC running at least 14 days first.

Pompano Wood Flooring can pass your slab-testing request to a flooring contractor before any boards are bought or delivered. Give the square footage and the floor you're considering, and ask which test will be used and for the readings in a written report.

Concrete Moisture Testing Methods Before Wood Floors

The test measures how much water the slab is still giving off. The floor's maker decides which test counts and what number passes, so pick the flooring first, then test against its instructions.

Small sensor caps set flush in drilled holes across a bare concrete slab, a gray handheld reader nearby

ASTM F2170 In-Situ RH Probes

Probes go into holes drilled to 40% of the slab's depth, which shows what the concrete will settle to once a floor seals the top. Wagner reads the standard as recommending 75% RH or less in general, with each maker's limit taking priority. Readings count after 24 hours since a 2018 revision; it used to be 72.

Provenza limit: 75% RH
Pergo locking engineered: below 80% RH
How many: 3 in the first 1,000 sq ft, plus 1 per additional 1,000 (Wagner)

Clear plastic dome sealed over a small dish of white crystals on a ground patch of concrete

ASTM F1869 Calcium Chloride Test

A dish of calcium chloride sits under a sealed dome and is weighed afterward to give pounds of vapor per 1,000 square feet in 24 hours. Wagner says it measures only what leaves the surface, sits 60 to 72 hours, and is no longer permitted on lightweight concrete. Some makers still accept it.

Provenza limit: 3 lbs per 1,000 sq ft
Pergo limit: 5 lbs per 1,000 sq ft per 24 hours

Gray handheld concrete moisture meter pressed flat on a bare slab beside a sliding glass door

Surface Meter Screening

A meter laid on the slab gives a reading in seconds, which makes it good for finding wet zones and choosing where the probes go. Wagner says it reads about the top half inch and falls under ASTM F2659, a preliminary guide, not F2170. Provenza accepts a Tramex reading up to 4.5 on the upper scale. Other makers may not.

Clear 6 mil polyethylene sheet rolled out over a concrete slab with seams overlapped and taped

Moisture Barrier Options When a Slab Fails

A failed test doesn't always end the project, but it changes the build-up. Wagner notes a "barrier" is really a retarder: it slows vapor, it doesn't stop it. Options depend on the installation method:

Glue-down: a moisture-retardant sealant the floor maker approves (Provenza); ARDEX requires moisture control if RH tops the floor's or adhesive's limit, or 99%
Floating: 6 mil polyethylene with seams overlapped 8 inches or more (Pergo)
Solid on a plywood base: 4 to 6 mil polyethylene, or asphalt felt in mastic, under the plywood (American Hardwood Information Center)

Installer kneeling on a bare concrete slab and checking it with a moisture meter before a wood floor goes down

Why Pompano Beach homeowners call Pompano Wood Flooring

One local flooring contractor calls back, not a bidding list
Asking costs nothing and commits you to nothing
Ask for the slab moisture readings in writing
Florida doesn't license flooring: ask for the business tax receipt and insurance certificates

Why a Slab Gets Tested Even When It Looks Dry

Provenza's instructions say visual checks aren't reliable, and the NWFA's magazine says every on-grade slab has moisture and always will, enough over time to warp, split or curl solid wood. That's why the NWFA recommends engineered wood below grade and why engineered can go on a slab at any grade level. The American Hardwood Information Center allows solid wood on on-grade or upper-floor slabs only with dry concrete, the right subfloor and vapor retarders, and says not to install hardwood at all if tests show too much moisture. Provenza also wants new concrete cured 60 to 90 days, and warns that a slab that tests dry can turn wet at another time of year.

Before the Test: Conditions and the Written Report

A reading only means something if the house was set up right and the report says how it was taken.

Run the AC
Pergo wants the HVAC on for at least 14 days before testing, and indoor humidity held in the range makers set.
Name the floor
Choose the product first so the report can be compared with that maker's limit.
Get it in writing
Test method (F2170, F1869 or meter), number of test spots, a sketch of where they were, each reading, and the date.
Plan the next step
If tile is coming up, test the bare slab after tile removal; if it's uneven, leveling follows the test, since ARDEX says its leveler isn't a vapor barrier (floor leveling).

See engineered hardwood installation.