Sub-Floor Preparation


  • Check for moisture content using the appropriate testing method. 
  • A new concrete slab usually takes 90 days or more to dry thoroughly depending on slab size and weather conditions.
  • Sub-floor must be flat, dry, free from residues and structurally sound.
  • A moisture barrier must be used. 
  • SOLID PLANK FLOORS: Nail down plank flooring must have proper sub-floor over the concrete. Planks should not be directly glued to concrete.  

There are certain materials that are not proper laminate flooring sub-floors. The sub-floor materials NOT suitable for laminate flooring:

  • Residential Carpet & Carpet Underlayment
  • Any Cushioned Flooring
  • Glued vinyl

If you have one of these types of flooring, you must remove it before installing your laminate. The appropriate types of laminate flooring sub-floor include:

  • Exterior grade plywood sub-flooring
  • OSB board
  • Concrete (that is at least 90 days old)
  • Existing wood that is not adhered to concrete
  • Vinyl that is not glued down to another sub-floor
  • Ceramic
  • Terrazzo
  • Particle board

Check Your Moisture Levels

Once any wood-based product has been acclimatized to a home, it usually has a stable moisture content. With that said, you should take a moisture reading before installing your flooring to make sure it is acceptable.

14% is the highest moisture reading acceptable for wood subfloors.

  • As a rule, most parts of the United States will have a rating of about 8% moisture.
  • Drier climates can drop as low as 4%.
  • Wet climates (such as the Southeast part of the United States) will increase to as bout 11% – 13%.

If your home is closed without ventilation, you could see your interior humidity level rise substantially. When this happens, your flooring will expand. Ventilating your home or running the HVAC system is highly recommended.




Check Your Building Codes

You’ll also want to make sure that your subfloor is up to building code requirements. Here are some of the most common requirements to test for:

  • If your flooring creaks when you walk on it, it must be repaired before you install your laminate flooring.
  • If your flooring sags in any section, it might be due to the joists below. Check these for any excess moisture, twists, or weak points.




Check For High Areas

High areas, such as joints with peaks in the sub-floor or any other ridges should be leveled. You can do this using a sander or by using a cement and latex leveling compound. Always let the compound dry completely before beginning any kind of installation.

With a wood sub-floor, you can install your laminate flooring directly over parquet, planks, or other type of wood flooring. 


updated 2-01-2019