Concrete Moisture Testing in Toronto & the GTA
In-situ relative humidity testing (ASTM F2170) on new and existing concrete slabs across Toronto and the GTA — for property managers, general contractors, and building owners installing flooring, coatings, or epoxy over concrete.
Concrete slabs release moisture for a long time after they're poured. The exact duration depends on slab thickness, mix design, ambient conditions, and how well the building is climate-controlled — but the general truth holds: a slab that looks dry on the surface can still be releasing enough moisture from below to destroy the finished floor installed on top of it. Vinyl adhesives lose bond. Wood expands and cups. Epoxy coatings blister, delaminate, and fog. Polished floors that were supposed to be permanent lift in patches.
The industry-standard test that catches this before the finished floor goes down is ASTM F2170 — in-situ relative humidity (RH) testing using probes sealed into holes drilled into the slab, left to equilibrate, and then read. Concrete Repair Plus performs ASTM F2170 moisture testing for property managers, general contractors, and building owners across Toronto and the GTA. We do the test to the standard, we write the report, and you take that report to whichever installer or manufacturer needs to see it.
This is a small line item on a project. It is also the line item that determines whether the six-figure floor above it lasts. If you're being asked to sign off on flooring installation over a slab and no one has produced a moisture report, this page is for you.
Why Flooring Over Untested Concrete Fails
Every finished-floor failure we get called out to diagnose over concrete fails for one of these reasons. All of them are avoidable with a written moisture report before the floor goes down.
The floor was installed before the slab was tested
The single most common failure. A new slab is placed, the surface looks and feels dry after a couple of weeks, the flooring installer is on the schedule, and the floor goes down. Sub-slab moisture continues to release into the finished floor for months — the adhesive lifts, the vinyl bubbles, the wood cups. The floor is a warranty claim before the building opens.
The slab was tested with the wrong method for the manufacturer's spec
Not every moisture test measures the same thing. Surface-only methods can pass a slab that ASTM F2170 in-situ RH testing would fail. Most finished-floor manufacturers now spec F2170 by name — using the wrong test gets you a report the manufacturer will not accept and voids the flooring warranty.
Too few probes for the slab area
One probe on a large slab does not characterize the slab. Manufacturer specs typically require a probe count that scales with square footage plus additional probes near known moisture sources — perimeter walls, columns, penetrations. Under-testing produces a report that reads fine and a floor that fails in the low corner nobody probed.
Probes were read before equilibration was complete
ASTM F2170 requires the probes to equilibrate inside the slab for a defined period before the reading is taken. Reading too early gives an artificially low RH number. The floor gets approved on paper; the failure shows up in the field.
No written report kept on file
A moisture reading spoken over the phone is not a report. A photograph of the meter is not a report. If the finished floor fails and there is no signed, dated, itemized written moisture report showing probe locations, readings, and equilibration timing, the flooring warranty conversation ends before it starts. We deliver every test as a signed written PDF.
When You Need Moisture Testing
Six scenarios where an ASTM F2170 report is the difference between an approved floor install and a warranty claim.
New Slab, Any Finished Floor Above
Any time flooring, coating, or epoxy is going down on a new slab, the finished-floor manufacturer's install spec will name a moisture threshold. Meeting it means testing to the standard the manufacturer references.
Slab-on-Grade in a Basement or Below-Grade Space
Below-grade slabs receive moisture from the surrounding soil for the life of the building. Testing before the flooring install is not optional if the finished floor is moisture-sensitive.
Existing Slab, Failed Finished Floor Above
When existing flooring lifts, bubbles, cups, or delaminates, the diagnosis starts with a moisture reading. The report tells you whether the slab is the cause and whether the replacement floor can go down or the slab needs remediation first.
Commercial Fit-Outs with a Flooring Line Item
General contractors coordinating flooring installers across multi-tenant fit-outs use the report as the sign-off document. One test per slab, one report per file, one less warranty argument later.
Polished, Epoxy, or Urethane-Cement Floor Systems
Coatings blister when applied over concrete that is still releasing moisture. Every reputable coating manufacturer names a testing standard in the install datasheet — F2170 is the most commonly referenced.
Insurance or Warranty Documentation Requested
When an insurer, manufacturer, or property warranty program asks for a moisture report on file, they mean a signed written PDF with probe locations, readings, timing, and the tester's credentials — not a verbal assurance.
Need a written condition report for your building? We deliver them free — formatted for your reserve-fund consultant and property manager.
How We Get It Right The First Time
- 01
Scope the Test to the Finished-Floor Spec
Before we drill anything, we read the finished-floor manufacturer's install specification and the flooring installer's requirements. That document names the standard, the threshold value, and often the probe count. Our written scope quotes probe locations, probe count, and expected timeline based on that spec — not our default.
- 02
Drill, Sleeve, and Seal the Probe Holes
Probes go into holes drilled to the depth defined by ASTM F2170 (typically referenced to slab thickness — we drill to the standard, we do not guess). Each hole is cleaned, a plastic sleeve is inserted, and the sleeve is sealed at the top so the probe reads the moisture inside the slab, not the surrounding air.
- 03
Equilibration
The probes are left in place to equilibrate for the period defined by ASTM F2170 before any reading is taken. This is the step most cost-driven contractors compress or skip — and it is the step that most invalidates a report if it is not honoured. We time the equilibration and log it in the report.
- 04
Take Readings and Cross-Check
At the end of equilibration, RH and temperature are read from each probe with a calibrated meter. Readings are logged against probe location, time, and ambient conditions. Where the finished-floor spec calls for multiple readings over time, we schedule the return visits.
- 05
Written Report, Delivered to Your File
Every test ends with a signed written PDF report — probe layout drawing, individual probe readings with timing, ambient conditions, tester credentials, the manufacturer specification the test was run against, and the pass/fail conclusion. Delivered digitally within one business day of the final reading. Your report is the document the installer, the manufacturer, or the insurer needs to see.
Materials & Methods
- ASTM F2170-compliant in-situ RH probes
- Calibrated RH and temperature meter
- Sealed probe sleeves per the standard
- Written probe-layout drawing per slab tested
- Signed PDF report delivered on completion
How Long It Lasts
Expected Service Life
Report Follows the Floor
Once the test is complete and the report is issued, that document lives with the building's flooring documentation for the life of the floor. It's what the flooring warranty is issued against, what the manufacturer references if a claim is ever filed, and what the next flooring installer refers to when a section is replaced years later. A ten-dollar file that saves six-figure disputes.
- Signed PDF report on file
- Probe layout drawing archived with the report
- Readings logged against equilibration timing
- Manufacturer spec referenced in the conclusion
Why Property Owners Choose Concrete Repair Plus
Off-Hours Crews
Night and weekend scheduling for parking garages, condo buildings, retail, and warehouses. Your tenants and operations are not disrupted.
Fully Insured & WSIB-Covered
$5M liability, WSIB clearance, and a written safety program. Clearance certificates and COIs delivered before mobilization.
Property Manager Reporting
Photo documentation of every step, scope sign-off, and itemized invoicing. We make audits, AGMs, and reserve-fund reporting painless.
GTA-Wide Coverage
One crew covering Toronto, Scarborough, North York, Etobicoke, Mississauga, Brampton, Markham, and Vaughan — full mobilization in 5–7 days for new buildings.
Engineering Coordination
We work directly with structural engineers and building consultants when restoration scopes require sealed drawings or third-party reports.
Long-Term Warranty
Written warranty on every commercial scope. Most parking garage and warehouse repairs carry 5–10 year coverage depending on system.
Common Questions
Related Services
GTA Service Area
Book a Free Moisture Testing Consult
Probe count and locations scoped to your slab and your finished-floor manufacturer's spec. Written report on completion — for your file, for your GC, for your warranty.