What can I use as underlayment?

Underlayment is an important component when installing flooring. It is installed underneath your finished floor to provide a smooth, even subfloor surface. Additionally, underlayment helps cushion your floor from minor imperfections in the subfloor, provides thermal insulation and sound absorption, and allows your flooring to “float” freely underneath. This helps prevent cracking, buckling, and noises. When selecting underlayment, consider your flooring type and subfloor conditions. The right underlayment will extend the life of your flooring and prevent costly repairs down the road. In this article, we will explore the most common underlayment options for various flooring types.

Underlayment for Laminate and Engineered Wood Floors

Foam Underlayment

Foam underlayment is one of the most popular choices for laminate and engineered wood flooring. It is an affordable option typically made from recycled materials. Foam underlayment comes in rolls of various thicknesses, such as 2mm, 3mm, and 5mm. Thicker foam provides better moisture protection and sound insulation. Here are some key benefits of foam underlayment:

• Cushions floors from subfloor imperfections
• Absorbs sound and impact noise
• Provides thermal insulation
• Allows flooring to float freely
• Easy DIY installation

The main downside of foam underlayment is that it compresses over time. So it may need to be replaced when reinstalling floors.

Cork Underlayment

Cork is a natural material made from the bark of cork oak trees. Cork underlayment provides insulation against noise and heat. It also absorbs vibration and impact very well. Cork is moisture resistant and won’t break down over time. Some benefits of cork underlayment include:

• Naturally moisture and mildew resistant
• Excellent sound and heat insulation
• High compression resistance
• Doesn’t break down over time
• Sustainable and renewable resource

The main disadvantages of cork are the higher cost compared to other underlayments and potential for mold growth if exposed to excessive moisture.

Rubber Underlayment

Rubber underlayment is typically made from recycled rubber tires. It boasts impressive moisture protection and sound insulation qualities. Rubber underlayment is available in rolls and tiles. Key features include:

• Superior moisture barrier
• Excellent impact sound insulation
• High durability and compression resistance
• Easy DIY installation
• Can level out minor subfloor imperfections

The main downsides of rubber underlayment are the higher cost compared to foam and potential odor during initial installation. The smell dissipates over time.

Felt Underlayment

Felt underlayment is a lightweight fiber material made from recycled plastic bottles or fibers. It is one of the more affordable underlayment options. Here are some benefits of felt underlayment:

• Low cost material
• Easy DIY installation
• Good sound insulation
• Smooths over minor subfloor imperfections
• Allows flooring to expand and contract

However, felt underlayment is not effective at moisture protection compared to rubber and cork. It is best suited for floating floors over completely dry, above-grade concrete.

Comparison of Underlayment Properties

Underlayment Type	Sound Insulation	Moisture Protection	Compression Resistance	Cost
Foam	Good	Minimal	Fair	Low
Cork	Excellent	Good	Excellent	Moderate to High
Rubber	Excellent	Excellent	Excellent	High
Felt	Good	Poor	Fair to Good	Low

Underlayment for Vinyl and Linoleum Floors

Cork Underlayment

Cork is a great option for vinyl and linoleum floors. It provides cushioning, absorbs sound, and resists moisture. Cork naturally inhibits mildew and mold growth. Make sure to get cork underlayment rated for vinyl flooring, which is constructed to withstand compression and indentation from vinyl.

Felt Underlayment

Felt underlayment is affordable and fairly easy to install under vinyl or linoleum flooring. It smooths over small bumps and dips in the subfloor. Choose a reinforced felt product as thicker vinyl flooring can indent standard felt over time. For moisture resistance, look for an enhanced felt with a moisture barrier film.

Foam Underlayment

Foam provides vinyl flooring good sound insulation and thermal properties. Seek out vinyl-rated foam underlayment that is designed to withstand compression from vinyl floors. Choose a thickness of 1/4″ or thicker for adequate cushioning. Adhesives on vinyl flooring may not stick properly to standard foam underlayment.

Rubber Underlayment

Rubber underlayment is highly durable, moisture resistant, and absorbs sound very well. It prevents indentations from vinyl flooring compared to softer underlayment. Rubber provides excellent insulation against both sound and heat transfer. It is a good solution for concrete subfloors and below grade installations. The higher cost is justified by the outstanding performance and durability.

Underlayment for Hardwood Floors

Felt Paper

Felt paper is the traditional underlayment used beneath hardwood flooring. It provides a smooth protective layer over the subfloor. Benefits include:

• Smooth surface for hardwood installation
• Prevents wood dust from contaminating subfloor
• Economical option
• Easy to cut and install

However, felt paper underlayment has minimal sound, moisture, and thermal insulating properties on its own. It is primarily used as a protective barrier.

Cork Underlayment

Cork is naturally moisture resistant making it an excellent match for solid hardwood flooring. Cork provides cushioning for hardwood as well as sound and heat insulation. Its high density prevents permanent indentations. Cork remains stable over time and won’t break down or compress excessively. This helps maintain the floor’s structure and aesthetics long term.

Rubber Underlayment

Rubber underlayment works very well under hardwood flooring. It prevents sound transfer through the floor while providing cushioning from subfloor imperfections. Rubber offers superb moisture protection, especially important for solid wood floors. This prevents warping or cupping issues. Like cork, rubber is highly resistant to compression damage. Overall rubber underlayment will help hardwood floors maintain integrity and last longer.

Foam Underlayment

Basic foam underlayment should be avoided under solid hardwood flooring. It does not provide enough moisture protection or compression resistance. Hardwood can permanently indent soft foam over time. Instead, use foam products specifically designed for hardwood flooring. These provide better moisture barriers, antimicrobial properties, and higher densities to prevent compression issues.

Underlayment for Concrete Subfloors

Underlayment selection is especially important when the subfloor is concrete. Concrete is prone to moisture issues and can transmit sounds easily. Popular underlayment choices for concrete subfloors include:

Cork

Cork resists moisture very well and provides thermal and sound insulation. Its high density prevents indentations from concrete. Choose thick cork underlayment rated for concrete subfloors.

Rubber

Rubber underlayment is naturally waterproof and blocks moisture rising from concrete slabs. It prevents sound transmission through the floor. Rubber’s high compression and indentation resistance extends the floor’s lifespan.

Foam

Use high-density vinyl-rated foam underlayment on concrete subfloors. Standard foam compresses too easily. Look for antimicrobial treatments as well since concrete tends to have higher moisture. Adhesives may not bond flooring as effectively to foam.

Felt

Felt underlayment helps smooth over variances and fills small cracks or voids in the concrete. However, it has minimal insulation or moisture protection. Choose a reinforced felt product rated for concrete subfloors. Or combine felt with a separate moisture barrier.

Underlayment for Radiant Heat Systems

Radiant floor heating systems require an underlayment rated to withstand the additional heat. Thermal insulation properties are also important to maximize heating efficiency. Recommended options include:

Cork

Cork is naturally thermal resistant and won’t compress excessively under radiant heat. It provides very good insulation to retain heat in the floor. Cork remains stable over an extremely wide temperature range.

Rubber

Rubber underlayment is designed to withstand contact with radiant heating systems. It resists heat degradation and prevents indentations. Rubber also insulates well to retain warmth in the flooring.

Foam

Use high-density foam products specifically rated for radiant heat systems. Standard foam may compress or melt under excessive heat. Ensure the foam provides thermal insulation and allows the floor to expand and contract freely.

Felt

Felt is not inherently designed for radiant heat systems. Seek out enhanced felt products made for radiant flooring with increased heat tolerance and insulation. Avoid standard felt as it provides minimal protection and insulation.

Underlayment Recommendations by Flooring Type

Flooring Type	Best Underlayment Options
Laminate	Foam, Cork, Rubber
Engineered Wood	Felt, Foam, Cork
Vinyl	Felt, Foam, Cork
Linoleum	Felt, Foam, Cork
Hardwood	Felt Paper, Cork, Rubber
Concrete Subfloor	Cork, Rubber, Foam
Radiant Heat	Cork, Rubber, Foam

Choosing the Right Thickness

Underlayment thickness ranges from 1mm to 10mm typically. Thicker products provide more cushioning and better insulation. Here are typical thickness recommendations by flooring type:

• Laminate flooring: 2mm to 5mm underlayment
• Engineered wood flooring: 2mm to 3mm underlayment
• Vinyl flooring: 2mm to 5mm underlayment
• Hardwood flooring: 2mm to 3mm underlayment
• Linoleum flooring: 2mm to 3mm underlayment
• Cork flooring: 1mm to 2mm underlayment

Use thicker underlayment in areas with heavy foot traffic, loud sound transmission, or radiant floor heating. For moisture protection, thicker rubber or cork layers prevent more water vapor penetration.

Underlayment Installation Tips

Subfloor Preparation

Ensure the subfloor is cleaned of debris, dust, grease, and old adhesives. Fill any major cracks or holes with a floor leveling compound. Check for squeaks or loose areas and re-secure boards or fasteners as needed.

Sheet Installation

For underlayment like foam, felt, or cork that comes in rolled sheets, start by cutting pieces to fit the room. Leave a 1/4″ gap between underlayment edges and walls. Use tape to join seams. Stagger seams from the flooring seams above. Extend material 2-3 inches up walls to insulate perimeter.

Tile Installation

Underlayment tiles interlock together. Arrange the tiles so seams offset from flooring seams. Use adhesive or double-sided tape for joining if needed. Leave 1/4″ gaps at walls. Stack tiles against walls 2-3 inches to insulate the perimeter.

Moisture Barriers

Install a separate moisture barrier film for concrete slabs or below grade levels. Overlap seams 6-12 inches and seal with moisture proof tape. Extend the barrier up walls 1-2 inches.

Final Floor Prep

Vacuum the underlayment before installing finished flooring. For adhesives or nails, check recommended fastener length to account for underlayment thickness. Follow all flooring manufacturer guidelines for underlayment use.

Conclusion

Choosing the right underlayment for your particular flooring project involves considering factors like flooring type, subfloor material, moisture levels, sound insulation needs, and budget. Cork, felt, foam, and rubber are common underlayment materials, each with different properties. For the best durability and performance, select an underlayment specifically rated and designed for your flooring and subfloor. With proper underlayment installed underneath, your flooring will last longer and look beautiful for years to come.