Soundproofing creates a quiet and comfortable living or working environment. Whether you’re minimizing noise from footsteps, voices, or household appliances, selecting the right underlayment material can make a significant difference. Underlayment is a foundational layer beneath flooring, designed to absorb sound and reduce vibrations, contributing to a quieter space. With various materials available, understanding their properties is crucial to making an informed decision.

Key Takeaways:

• Material Matters: The type of underlayment material you choose directly impacts its soundproofing effectiveness. Rubber, cork, foam with sound barriers, felt, and acoustic membranes each have unique properties suited to specific needs. Rubber is highly dense and compelling for impact and airborne noise, while cork is an eco-friendly option for light soundproofing. Selecting the right material ensures compatibility with your flooring and desired noise reduction.
• STC and IIC Ratings are Crucial: Sound Transmission Class (STC) and Impact Insulation Class (IIC) ratings measure how effectively a material reduces airborne and impact noise, respectively. A high STC rating indicates better performance against sounds like voices or music, while a high IIC rating indicates better reduction of impact noise, such as footsteps. Prioritize materials with high ratings for the type of noise you’re addressing.
• Installation Enhances Effectiveness: Proper underlayment installation is as necessary as the material. Uneven surfaces, gaps, or improper placement can compromise soundproofing. Preparing the subfloor, correctly aligning the underlayment, and combining it with other soundproofing techniques—such as sealing gaps or adding acoustic panels—can significantly enhance its performance.

Key Factors to Consider When Choosing Soundproofing Underlayment

Material Type

Different materials offer varying soundproofing performance, durability, and environmental friendliness. Common options include:

• Rubber: Known for its density and durability, rubber is highly effective at reducing impact and airborne noise. It is ideal for high-traffic areas but can be more expensive.
• Cork: A sustainable and lightweight material, cork is suitable for minor soundproofing and offers moderate noise absorption.
• Foam: Often combined with sound barriers, foam is cost-effective and works well for reducing impact noise, though it may be less effective for airborne sound.
• Felt: Provides good sound absorption and pairs well with hardwood flooring.
• Acoustic Membranes: These are thin yet effective for soundproofing impact and airborne noise, making them suitable for retrofitting projects.

Thickness

While thickness can contribute to soundproofing, it is not the determining factor. Denser materials often outperform thicker but less dense options.

• Thin but Dense Materials: Acoustic membranes can outperform thicker but less dense underlayments.
• Floor Height Considerations: Thicker underlayments may raise the flooring level, impacting door clearance and room aesthetics.

Sound Transmission Class (STC) Rating

The STC rating measures how well a material blocks airborne noise, such as voices, music, or TV sounds. Higher STC ratings indicate better performance.

• Ideal for Walls and Floors: For effective soundproofing, look for materials with an STC rating of 50 or above.
• Supplementing with Other Methods: While underlayment helps, additional soundproofing (e.g., wall insulation) may be needed for airborne noise.

Impact Insulation Class (IIC) Rating

The IIC rating indicates how well a material reduces impact noise, such as footsteps or dropped objects.

• Critical for Multi-Level Buildings: In apartments or multi-story homes, a high IIC rating minimizes noise transfer to lower levels.
• Target Ratings: An IIC rating of 50 or above is generally sufficient for residential needs.

Compatibility with Flooring Type

The effectiveness and durability of underlayment also depend on its compatibility with the type of flooring being installed.

• Hardwood or Engineered Wood: Felt and rubber underlayments are excellent choices as they protect the wood and enhance soundproofing.
• Laminate or Vinyl Flooring: Foam underlayment with vapor barriers is commonly used to prevent moisture damage.
• Tile Flooring: Rubber underlayment is preferred due to its ability to absorb impact and prevent cracks.

Best Underlayment Materials for Soundproofing

Choosing the right underlayment material can make a significant difference in reducing noise. Here are some of the best options available, along with their key features and applications:

Rubber Underlayment

• Features: Rubber is dense, durable, and eco-friendly, often made from recycled materials. It boasts high Sound Transmission Class (STC) and Impact Insulation Class (IIC) ratings, making it highly effective for airborne and impact noise.
• Applications: Ideal for multi-family homes, apartments, or commercial spaces with high noise levels.
• Advantages:
  • Excellent noise reduction
  • Long-lasting
  • Resistant to mold and mildew
• Considerations: Higher cost compared to other materials.

Cork Underlayment

• Features: Cork is lightweight, sustainable, and provides moderate soundproofing. It’s a good option for reducing minor impact and airborne noise.
• Applications: Suitable for eco-conscious homeowners and low-traffic areas.
• Advantages:
  • Environmentally friendly
  • Resistant to mold and mildew
  • Cost-effective for light soundproofing
• Considerations: More effective for heavy-duty soundproofing or high-traffic areas.

Foam Underlayment with Sound Barriers

• Features: Foam underlayments are budget-friendly and often come with integrated sound barriers, adding sound absorption layers.
• Applications: Commonly used under laminate and vinyl flooring.
• Advantages:
  • Affordable
  • Easy to install
  • Includes moisture resistance features
• Considerations: Less practical for blocking airborne noise.

Felt Underlayment

• Features: Felt is dense and durable, making it practical for sound absorption under hardwood and engineered wood floors.
• Applications: Works well in homes with wood flooring where soundproofing is a priority.
• Advantages:
  • Good noise reduction
  • Provides cushioning for hardwood floors
  • Made from recycled materials
• Considerations: Only suitable for damp environments with added moisture barriers.

Acoustic Membranes

• Features: Acoustic membranes are thin but highly effective at reducing airborne and impact noise. They can be layered with other underlayments for added performance.
• Applications: Great for retrofitting and situations where floor height is a concern.
• Advantages:
  • High-performance soundproofing
  • Minimal impact on floor height
  • Versatile for various flooring types
• Considerations: Higher cost per square foot.

Comparison Table of Common Underlayment Materials

Material	Pros	Cons	Price Range	Suitable Flooring Types
Rubber	High STC/IIC ratings, durable, eco-friendly	Expensive, heavier to install	$$$$	Tile, hardwood, laminate
Cork	Sustainable, lightweight, affordable	Moderate soundproofing, less durable	$$	Hardwood, laminate
Foam with Barriers	Cost-effective, easy to install, moisture-resistant	Less effective for airborne noise	$	Laminate, vinyl
Felt	Dense, suitable for hardwood, eco-friendly	Requires moisture barriers in damp areas	$$$	Hardwood-engineered wood.
Acoustic Membranes	Thin, excellent noise reduction, versatile	Expensive	$$$$	Tile, hardwood, laminate, retrofitting

Installation Tips for Soundproofing Underlayment

Preparing the Floor

Before installing the underlayment, the subfloor must be appropriately prepared to ensure smooth installation and optimal performance:

• Clean the Subfloor: Remove any debris, dust, or dirt from the subfloor. Use a vacuum or broom to clean the surface.
• Inspect for Damage: Check the subfloor for cracks, holes, or uneven areas. Fill cracks or holes with a leveling compound and sand down uneven spots.
• Dry the Subfloor: Ensure the surface is parched to prevent mold or mildew growth under the underlayment.
• Install a Moisture Barrier (if needed): To protect against moisture damage in damp environments or concrete subfloors, install a vapor barrier before laying down the underlayment.

Correct Placement and Securing of Underlayment

Proper placement is crucial to prevent gaps that can allow noise to pass through:

• Lay the Underlayment Flat: Roll or lay the underlayment flat across the subfloor. Align the edges carefully to avoid overlaps or gaps.
• Cut to Fit: Trim extra material around corners, edges, and fixtures with a utility knife.
• Secure in Place: Depending on the material, secure the underlayment using adhesive, tape, or staples:
  • For rubber or cork: Adhesive or double-sided tape is often used.
  • For foam or felt: Staples or tape can suffice.
• Seal the Edges: Use tape to seal seams between underlayment sheets. This prevents noise leaks and improves the overall soundproofing performance.
• Avoid Overlapping: Overlapping edges can create uneven surfaces, which may affect the flooring above.

Combining Underlayment with Other Soundproofing Methods

Underlayment works best when integrated with additional soundproofing techniques:

• Acoustic Caulking: Seal gaps around the room’s edges or at the base of walls with acoustic caulk to block airborne noise.
• Floating Floors: Pair underlayment with floating floor systems to enhance sound absorption, especially for laminate or engineered wood.
• Acoustic Panels: Install acoustic panels on walls or ceilings to reduce airborne noise.
• Double Layering: Consider layering the underlayment with an acoustic membrane or adding a secondary underlayment layer for maximum soundproofing.

Additional Tips

• Always follow the manufacturer’s instructions for the specific underlayment material.
• Test-fit a small flooring section over the underlayment before completing the installation to ensure a smooth finish.
• Use tools like a rubber mallet or floor roller to ensure a snug fit without damaging the underlayment.

FAQs

What is the most effective underlayment material for soundproofing?

Rubber underlayment is considered one of the most effective materials due to its high density and excellent sound absorption properties.

Can underlayment completely soundproof a room?

While underlayment significantly reduces noise, complete soundproofing often requires combining it with other methods, such as wall insulation or acoustic panels.

Is thicker underlayment always better for soundproofing?

Not necessarily. The material’s density and soundproofing ratings (STC/IIC) are more crucial than thickness alone.

Can I use the same underlayment for all flooring types?

To ensure compatibility and effectiveness, underlayment should be chosen based on the specific flooring type (e.g., hardwood, tile, laminate).

How does underlayment affect impact noise versus airborne noise?

Underlayment is typically more effective at reducing impact noise (e.g., footsteps) than airborne noise (e.g., voices, music). For airborne noise, additional measures like wall insulation may be needed.

Conclusion

Soundproofing underlayment is crucial for creating a quieter and more comfortable environment, whether in a residential or commercial setting. Choosing the right material involves evaluating factors such as the noise to be reduced, the flooring type, and the underlayment’s STC and IIC ratings. Options like rubber, cork, foam, felt, and acoustic membranes each offer unique benefits, allowing you to tailor the solution to your needs.

Proper installation is as vital as selecting the right material. Preparing the subfloor, ensuring precise placement, and sealing seams effectively can significantly enhance soundproofing performance. Combining underlayment with soundproofing techniques, such as acoustic panels or caulking, can improve results.

By understanding the properties, benefits, and installation methods of soundproofing underlayment, you can make informed decisions that meet your goals for noise reduction and flooring compatibility.