The Complete Guide to Floor Underlayment

Floor underlayment is a layer of material placed beneath the flooring to create a smooth, level surface for installation. It helps even out small bumps and dents in the subfloor and can improve the comfort of the floor. Additionally, it enhances the durability and performance of the flooring.

Underlayment provides strong support for your flooring and reduces noise. Certain types also protect your floor from moisture that may arise from damp subfloors. Without underlayment, your flooring could warp, become damp or develop mildew.

Underlayment serves several important functions, including:

• Leveling the surface: It helps smooth out bumps and dents on the subfloor, ensuring a flat and even surface for flooring installation.
• Extra Cushioning: It adds a layer of cushioning that increases the comfort and lifespan of your flooring. This helps prevent wear and tear.
  
• Noise reduction: The cushioning effect of underlayment reduces noise from footsteps and impact, making the room quieter.
• Durability: Underlayment extends the life of your floors by preventing damage from moisture and foot traffic. It’s also resistant to UV exposure.
  
• Comfort: It adds a soft, smooth layer, making your floor less hard to walk on.
  

Several types of floor underlayment are available, but four common ones are widely used

High-density foam is the best choice for laminate flooring. Foam underlayment allows for the expansion and contraction of laminate floors, which helps prevent damage. It’s also long-lasting, provides a smooth subfloor, and reduces sound transfer.

High-density foam is also a popular choice for vinyl plank flooring. It helps prevent dents in the vinyl surface and protects the spongy layer from degradation. Cork is also a good option, as it is naturally anti-microbial.

Felt is commonly used as underlayment for hardwood floors because it provides a solid surface without causing moisture problems that could warp the planks. Cork is another good choice for hardwood floors, as it resists moisture and helps support heavy loads. Cork is especially useful in kitchens or other damp areas.

While flooring underlayment enhances the floor's comfort and performance, vapor barriers protect it from moisture. In some cases, both layers may be necessary — first a vapor barrier to block moisture, followed by a flooring underlayment for sound or cushioning. The two serve distinct functions but can be used together for optimal flooring protection and performance, particularly in moisture-prone areas.

With so many options available, it’s important to choose the right underlayment based on your specific needs:

• Foam Underlayment: Foam is lightweight, easy to install and provides good cushioning and soundproofing. It is ideal for upper-level floors or ceilings but is vulnerable to moisture damage.
• Felt Underlayment: Felt is a budget-friendly option that creates a level surface and offers good sound absorption. While it’s not as soft as foam or cork, it still provides cushioning. Felt is somewhat moisture resistant, but should only be used in dry areas, as excessive moisture can damage it.
• Cork Underlayment: Cork is an excellent choice for areas prone to mold and mildew. It is soft, compressible and performs well in both hot and cold environments. Cork is ideal for basements or other concrete-floor applications.
• Rubber Underlayment: Rubber is a durable, waterproof material that absorbs sound well. It’s suitable for damp areas, thanks to its thickness and resistance to moisture. Additionally, rubber is often more affordable than other underlayment options.