Qualifying concrete moisture: the exclusion that saves flooring jobs

Concrete slabs can hold more moisture than flooring adhesives tolerate, and many specs put testing and remediation on the flooring contractor without stating the slab's condition. Qualify it in writing: who tests and by what method, the moisture and pH limits your price assumes (usually the manufacturer's published limits), and that mitigation beyond those limits is excluded or priced separately per square foot. Without that, your price is a bet on the slab.

By Michael Reddy, IntelBid

After this lesson you can

Explain why slab moisture is a flooring contractor's biggest risk
Write a moisture qualification that answers the four key questions
Offer mitigation as a unit price or alternate instead of absorbing it

Why does slab moisture matter so much?

Moisture and alkalinity rising through a slab can break down adhesives and cause bubbling, lifting, curling and odors — and flooring warranties typically don't cover failures above the manufacturer's limits. New slabs can take a long time to dry, and some older slabs never do. When the floor fails, the flooring contractor is the first call.

What must your qualification answer?

Who tests
Your company, an independent agency hired by the owner or GC, or nobody. If you test, price it — the test count comes from the standard.
How and when
The test method — commonly ASTM F2170 relative humidity or ASTM F1869 calcium chloride, plus pH. These standards expect the space to be at service conditions before testing, so testing usually can't happen until the building is enclosed and conditioned.
Which limits apply
The flooring and adhesive manufacturers' published moisture and pH limits for the specified products — not a number you remember from another job.
What happens above the limits
Mitigation is excluded and priced as a change, offered as a unit price, or offered as an alternate — but never left unsaid.

“Responsible for a suitable substrate” is unlimited scope

Broad spec language that makes the flooring contractor responsible for providing an acceptable substrate, with no slab data, has no ceiling. Ask a question during bidding, and qualify it in your proposal either way.

Sample qualification language

“Price assumes the concrete slab meets the flooring and adhesive manufacturers' published moisture and pH limits when tested per ASTM F2170 and the manufacturer's pH procedure, with the building enclosed and at service conditions. Moisture testing is [included / by others]. Moisture mitigation, if results exceed those limits, is excluded and available at $___ per SF. Delays waiting for the slab to reach acceptable conditions are not included.”
— Example to adapt — have large contracts reviewed

Ways to price the risk instead of absorbing it

Option	How it works	Best when
Mitigation unit price	A price per SF, applied only to areas that fail testing	Slab condition is unknown at bid time
Add alternate	A priced line for a mitigation system or a higher-tolerance adhesive system across the job	The owner may want protection up front
Included allowance	A stated amount of mitigation included, with a unit price beyond it	The GC wants a complete number
Testing as its own line	Priced tests plus a return trip if the slab isn't ready	The spec puts testing on you

Don't forget the schedule

A slab that tests high can hold up your installation for weeks. State that your schedule assumes acceptable test results, and that remobilizing after waiting for the slab to dry is a change. Ask early whether the owner or GC will test in advance — early results turn a surprise into a plan.

Who pays for moisture mitigation on a flooring job?

Whoever the contract makes responsible. Specs often assign it to the flooring contractor, so qualify your proposal: state the limits your price assumes and exclude or separately price mitigation above them.

What moisture limit should a flooring proposal state?

The published moisture and pH limits of the specified flooring and adhesive manufacturers, tested by the method they reference, rather than a generic number.

When can concrete moisture testing be done?

Common test standards expect the slab and space to be at service conditions before testing, so testing usually waits until the building is enclosed and the HVAC is running.

Key points

Answer four questions: who tests, how and when, which limits, what happens above them.
Use the manufacturers' published limits for the specified products.
Price mitigation as a unit price or alternate — never leave it unsaid.

In IntelBid · Proposal builder

The limit and the price, side by side

Add your moisture qualification as a note on the proposal — notes print just above your standard exclusions — then add mitigation as its own priced line or an Add alt line, so the GC sees both the limit your price assumes and what it costs if the slab fails.

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About the author. Michael Reddy builds IntelBid, bid management software for commercial flooring subcontractors. These lessons come from the bid desk: how the work is priced, won and paid for.