Floor underlayment is a thin layer of material that is installed between the subfloor and a finished floor. Underlayment has several advantages including cushioning, moisture protection, noise reduction, insulation, and surface correction. This article explores these topics as well as the best floor underlayment for a variety of example projects.
The following topics are covered in this floor underlayment buyers guide.
The key reasons to add underlayment under your flooring include the following.
The table below contains our favorite floor underlayment by material type.
Product | Price | Flooring Type | Material Type |
ROBERTS “Serenity Foam” Underlayment | Check Price on Amazon | Laminate Engineered Wood | Foam |
ROBERTS Super Felt® Underlayment | Check Price on Amazon | Laminate Engineered Wood | Felt |
Schluter DITRA Underlayment | Check Price on Amazon | Tile | Polyethylene |
Note: since prices can change day-to-day, direct links are provided to check current pricing.
Our favorite foam underlayment for projects on a budget is ROBERTS Serenity Foam Underlayment (Model 70-010). It is a competitive option to the big box stores. This underlayment is manufactured with open cell polyethylene foam. It measures 3/32” thick.
As a basic foam underlayment, it is best used with laminate and wood floors above grade. It can also be used on concrete floors if used in conjunction with a moisture barrier.
It does not have an adhesive backing. You will need tape to seal the seams or apply an adhesive to bond the material to the floor.
Our favorite felt underlayment is the ROBERTS Super Felt® Underlayment. It is suitable for use below grade, at grade, and above grade. The underlayment works great on laminate, engineered wood, and concrete floors.
This underlayment has a plastic film layer that serves as a moisture barrier which helps prevent moisture from seeping up and damaging your finished flooring. It can also be installed on a radiant heat floor.
The ROBERTS Super Felt® Underlayment has good noise reduction properties. The underlayment has a “Sound Transmission Lost Test” (STC) rating of 66. Its “Impact Sound Transmission Test” (IIC) is rated at 67. The underlayment comes with an adhesive strip that easily allows you to link each run. This makes seaming the underlayment together quick and effective.
The best underlayment for tile floors is Schluter DITRA. The DITRA product is a polyethylene underlayment with a grid structure top in the style of an egg crate and a fleece backing. It is designed specifically for ceramic and stone tile installations.
DITRA is an uncoupling membrane that provides a separation layer between the tile and the subfloor. This separation layer prevents tile and grout from cracking because it allows movement as materials expand and contract from temperature changes, humidity, and other environmental factors.
Schluter DITRA is a great alternative to cement board which is usually used with tile floor installations. It costs less than cement board, is lighter weight, and can carry the load of heavy tile.
DITRA is waterproof which makes it ideal for areas where tile is typically installed such as bathrooms where water damage is a risk. When installed correctly, this product will help protect your OSB or plywood subfloor from splashes and accidental overflows.
The egg crate-style top serves as a matting for the tile to lay on top of. This allows excess water that seeps through the tile flooring to have a place to drain without damaging the finished floor.
The fleece backing ensures a tight bond to the subfloor with a layer of Thin-set mortar. Thin-set is used to bond the underlayment to the subfloor and the tile to the underlayment.
The DITRA underlayment comes in two sizes. The standard size is 1/8” and the DITRA-XL size is 5/16”.
The DITRA-XL is suitable for subfloors installed on joists that are spaced 24” on center. The XL model allows a greater movement accommodation for natural stone tile and oversized tile. Since it is thicker, it can also be used to raise the tile, making it flush with flooring that sits higher (such as hardwood). This makes the transition between rooms look seamless.
Q: How is underlayment attached to the subfloor?
A: It depends on the type of subfloor and the material the underlayment is made of. If the subfloor is concrete, an adhesive is required because you cannot staple into concrete. An adhesive is also required if the underlayment has a moisture or vapor barrier. Staples create holes and you do not want holes in a barrier meant to protect your subfloor from moisture. If you are applying the underlayment to a wood subfloor, without a moisture barrier, and the manufacturer allows staples for your particular product, then the underlayment can be stapled to the subfloor.
Q: What type of underlayment should be used for hardwood floors?
A: Felt underlayment is most commonly used with hardwood floor installations.
Q: What are the benefits of using floor underlayment?
A: Underlayment offers cushioning, moisture protection, noise reduction, surface correction, and insulation.
Q: Is underlayment necessary for all types of flooring?
A: Not for hard floors, but an underlayment is recommended because it’s the foundation of your floor installation. In most cases a padded underlayment is required for carpet.
Q: What types of floor underlayment are available?
A: The most common types of underlayment are foam, rubber, felt, and cork.
Q: How much underlayment do I need for my project?
A: Purchase about 15% more than the square footage you are covering. For example, if your room is 15’ x 20’, you are covering 300 square feet. Plan on purchasing about 350 square feet of material. If each roll of underlayment is 100 square feet, you would need 4 rolls.
Q: Can I install underlayment over concrete?
A: Yes, but there are special considerations when installing underlayment over concrete.
Q: Can I install underlayment over an existing floor?
A: Generally, yes. However, make sure the floor you are installing over is in good, solid condition since it is serving as the foundation for your new floor. A major exception is hardwood floors. It is not recommended installing hardwood floors over an existing floor due to issues with expansion and contraction. If you choose to install over an existing floor, consider using an underlayment that is designed for that purpose.
Q: Is it necessary to use a moisture barrier with floor underlayment?
A: A moisture or vapor barrier is necessary when installing over concrete, installing a floor at grade or below grade, rooms subject to humidity or has historically been prone to moisture, and rooms such as kitchens, mudrooms and bathrooms where moisture can be reasonably expected.
Q: Are there considerations for underlayment in different climates?
A: In humid locations or areas prone to moisture, an underlayment that has a vapor barrier and suitable for expanding and contracting is required.
Q: Why is waterproof underlayment important?
A: Waterproof underlayment should be installed in the bathroom, kitchen, laundry room, mudroom, and any other areas that are prone to water. For example, if kids splash water out of a bathtub, a toilet overflows or leaks, washing machine overflows, pipes bust, or any other scenario when water comes in contact with the floor, a waterproof underlayment will save your subfloor from damage.
Q: What can be done to prevent tile from cracking?
A: To prevent tile from cracking it is imperative the tile is installed on a stiff, solid, and completely flat surface. Otherwise, the tile can shift and has a high risk of cracking over time. Tile is typically installed on cement board or an underlayment designed specifically for tile such as Schluter DITRA.
When purchasing floor underlayment, there are a few key items to consider.
The different types of materials floor underlayment are made of include foam, cork, rubber, felt, and cement board.
Each of the material types are described below in detail. However, in cases where the floor manufacturer requires a specific type of material for the underlayment, follow the manufacturer’s directions.
Foam is the most popular type of underlayment as it is relatively inexpensive, lightweight, easy to install, provides cushioning, and in some cases insulation.
It is a basic, but versatile underlayment that can be used under vinyl, laminate, and wood floors. It is offered as a thicker material for carpet to provide extra cushion.
Foam underlayment is typically manufactured from two types of material – polyethylene and polyurethane. Polyethylene is lightweight, flexible, and usually cheaper than polyurethane. Polyurethane is a higher quality material which does a better job at dampening sounds, providing a layer of insulation, and is overall more durable than underlayment made of polyethylene.
Rubber is the most durable type of underlayment due to its strength and flexibility. This makes it a great option for areas with high foot traffic.
Rubber is one of the best materials for areas where moisture is a concern, such as basements, bathrooms, or mudrooms.
Rubber underlayment is a viable option for laminate, carpet, or real wood floors. However, it is not recommended for use under vinyl. Rubber contains oils that can interfere with the adhesive on vinyl floors and can cause staining. Foam or cork underlayment is the better option for vinyl floors.
Cork underlayment is a great option for sound absorption and noise reduction. It is commonly used in apartments, multi-family housing, and other structures where sound transmission is a concern.
Cork is the most environmentally friendly material of the different types of underlayment.
Cork should not be used in damp environments unless it is specifically designed for moisture prone areas or coupled with a vapor barrier.
Felt underlayment is comparable to foam, but denser. It great for noise reduction, cushioning, and providing an extra layer of insulation.
Felt can be used on all floor types. It is not suitable for damp areas such as bathrooms, laundry rooms, and basements.
Felt underlayment is made by pressing and condensing fibers together. In many cases it is made of recycled materials which makes it an eco-friendly option.
Cement board underlayment is made from cement and fibers. It is very strong and sturdy as it is often reinforced with wire or mesh. Cement board is typically used with tile installations since tile requires a flat and sturdy underlayment to prevent them from shifting and cracking.
Cement board is water resistant which is ideal for areas where tile is typically installed such as bathrooms, kitchens, and laundry rooms.
Before getting started with installing floor underlayment, measure the space you are covering to determine how much material you will need. Be sure to purchase enough to allow about three inches of overlap between runs.
The following are high level steps that will suffice for most installations. As always, follow the manufacturer’s instructions when specific instructions are provided.
The type of floor you are installing (i.e. vinyl, laminate, wood, tile, etc.) determines the type of underlayment material required.
In wet areas such as a bathroom around bathtubs and showers, be sure to use underlayment that is waterproof and specifically designed for damp or wet areas.
There are special considerations on concrete floors or below grade areas such as a basement. Vapor barriers are often installed to prevent moisture from rising and damaging the finished floor.
Remove the old flooring and dispose of it. After the old flooring has been removed, you will need to prepare your subfloor by repairing any unevenness, cracks, or other minor imperfections such as raised nails.
It’s important that your subfloor lays as flat as possible. Underlayment can correct minor unevenness, but if it is significantly out of plumb the floor will need to be repaired before proceeding.
If the floor is below grade (i.e. in a basement) small cracks in the subfloor can allow moisture to seep through and cause damage to the underlayment and finished floor. Any cracks in the cement will need to be repaired before moving forward with the installation.
Finally, you will need a clean surface to work on. Be sure to sweep up any dust and debris before installing the underlayment.
After the subfloor has been prepped, the next step is to trim and lay the underlayment. In most cases, the underlayment comes in a roll.
Begin on one side of the room and start unrolling the underlayment. Leave about three inches of extra material to overlap the next run.
Be sure to trim around walls, pipes, doorways, air vents, and any other permanent fixtures in the room. A utility knife can be used to trim.
Underlayment is attached to the subfloor by staples or adhesive. It’s best to do a “dry install” first to make sure you have made the correct cuts before permanently bonding the underlayment to the floor.
Adhesive should be used in lieu of staples for installations that contain a moisture or vapor barrier. Puncturing a vapor barrier with staples would allow liquid to leak through the barrier. Installations over concrete also require an adhesive.
Foam or felt underlayment installations can be stapled to a wood subfloor as long as there is no moisture barrier and it is allowed per the manufacturer’s instructions.
As always, be sure to check the manufacturer’s instructions in case there are steps that need to be taken for your specific product.
The following tools are required to install floor underlayment.
When purchasing floor underlayment, there are a few measures or ratings that can be used for comparison.
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