Underlayment is not primarily designed to fix significant unevenness in a subfloor. Its main functions are to provide additional support, cushioning, moisture protection, and sound insulation for the flooring material being installed. While certain types of underlayment may have some levelling properties, they are generally limited in their ability to correct major irregularities in the subfloor.
If you’re dealing with a noticeably uneven subfloor, it’s essential to address the issue directly rather than relying solely on underlayment to solve the problem. Depending on the severity of the unevenness, you may need to:
- Level the Subfloor: Use self-levelling compounds or floor patching materials to smooth out significant bumps, dips, or depressions in the subfloor. This process involves applying a liquid compound that levels itself out to create a flat surface.
- Sand or Plane High Spots: If there are high spots on the subfloor, you can sand them down or use a plane to flatten them to the level of the surrounding areas.
- Shim Low Spots: For low spots or depressions, you can use shims or thin strips of wood to raise the floor to the desired level.
- Reinforce Weak Areas: If the subfloor is weak or structurally unsound, reinforce it by adding additional support, such as plywood or blocking.
- Consult a Professional: If you’re unsure how to properly address unevenness in the subfloor, it’s advisable to consult with a flooring professional who can assess the situation and recommend the appropriate course of action.
While underlayment can provide some minor levelling and smoothing effects, it’s best used in conjunction with proper subfloor preparation techniques to ensure a stable and even surface for the installation of hard flooring.