Before installing any flooring, especially laminate or engineered wood, your concrete subfloor needs to be flat and smooth. Even slight bumps or dips can lead to soft spots, cracking, or visible gaps in your floor. An uneven concrete base can lead to
- Bouncy or noisy floors,
- Gaps or seams opening,
- Premature wear or delamination.
- Voided flooring warranties
Here are some proven methods to fix and level an uneven concrete subfloor.
Step-by-Step: How to Level a Concrete Subfloor
1. Identify the Problem Areas
- Use a 6–10 foot straightedge or level.
- Slide it across the floor in multiple directions.
- Mark high spots and low spots with chalk or tape.
2. Clean the Concrete Surface
- Sweep and vacuum to remove dust, debris, or grease.
- Moisture test the concrete is strongly suggested before moving forward.
3. Grind Down High Spots
- Wear proper safety gear to protect against dust and the noise.
- Use a concrete grinder or angle grinder with a diamond cup wheel.
- When grinding, feather edges gradually to avoid noticeable transitions.
4. Fill Low Spots with a Floor Leveler
- Use a self-leveling compound for low spots or dips.
- Let it fully cure before flooring installation. This can take over 24 hours
Always follow the manufacturer’s instructions for mixing and installation.
5. Recheck the Surface
- After repairs and it has fully cured, use your straightedge to make sure it's level.
- Most flooring types allow for a tolerance of 1/8" over 6 feet.
Bottom Line:
A level subfloor is the foundation of your home and flooring installation. Take the extra time to get it right and protect your flooring. Your Bank Account (and your feet) will thank you.