3) Subfloor

1. Check subfloor moisture level

Wooden subfloor moisture reading must not exceed 12% and differential between boards and subfloor must be less than 4%. If moisture reading is too high, postpone installation, and find moisture source and correct it. If needed, raise heat and increase ventilation until proper conditions are met.

Owner and installer are solely and jointly responsible for pre-installation subfloor moisture level check and must ensure that it is, and remains, within the recommended range.

2. Check subfloor conditions

Check soundness of subfloor and correct if necessary. It must also be flat. If necessary, flatten down any irregularities using #20 grit paper or fill any uneven spots with leveling compound.

3. Clean subfloor

Subfloor must be clean and free of contaminants.