Installing flooring without proper subfloor testing is like building on quicksand—it might look fine at first, but failure is only a matter of time. Whether you’re working with concrete, wood, or hybrid substrates, subfloor testing is the most important step most teams rush past.
Here’s how to slow down, test right, and set your installation up for long-term success.
Why Subfloor Testing Matters
Most flooring failures trace back to unidentified moisture, flatness issues, or weak substructure bonding. These issues can:
- Break adhesives loose
- Warp boards or planks
- Void warranties
- Invite mold growth
- Lead to costly reinstallation
Proper testing validates that the subfloor is dry, flat, clean, and ready to perform under pressure.
Core Testing Practices Before Flooring
Here are the baseline practices every project should follow:
✅ 1. Concrete Moisture Testing
Use RH probes (ASTM F2170) or Calcium Chloride (ASTM F1869) to check moisture levels. RH testing is the standard for most resilient and adhesive-based systems.
✅ 2. Floor Flatness and Levelness
For large installs, especially in warehouses or offices, check FF/FL values (ASTM E1155) to ensure proper tolerances.
✅ 3. Bond Strength (Adhesion)
Use pull tests or bond tests to validate adhesion strength—especially critical for coatings or sealers.
✅ 4. Surface Cleanliness
Dust, oils, laitance, and curing compounds must be removed. Surface prep (grinding or shot-blasting) may be required.
✅ 5. Ambient Conditions
Record temperature and relative humidity in the space. Many adhesives are sensitive to environmental variables during install.
When Should You Test?
Testing should occur after concrete has cured but before any flooring materials arrive on site. For remodels or takeovers, always test after demo and surface prep.
For a walkthrough of the typical process, check out What to Expect from a Professional Floor Testing Procedure.
Bonus Tip: Don’t Rely on One Test Alone
Cross-reference results:
- Use RH and calcium chloride to get both surface and in-depth insights
- Pair visual inspection with digital measurement tools
- Document everything to protect your timeline—and your liability
Final Thought
Testing your subfloor isn’t an extra—it’s the foundation of your floor. Done right, it protects your materials, your margins, and your reputation. Before you install, test like you mean it.