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How to Buy Underlayment

The 4 W's of Underlayment

While many flooring products today feature attached underlayment, you may have questions about when you what it is and when you need to worry about it.

What exactly is underlayment?

Underlayment is installed on top of the subfloor, and provides a barrier between your subfloor and your new floor. The underlayment layer may be made of felt, foam, cork, rubber, cork/rubber, or a mixture of wood products. Underlayment can help provide cushion for more comfortable walking and standing, warmth (especially in basement areas or on concrete slabs), and sound insulation, reducing noise levels.

When do you need a layer of underlayment?

Damp Areas

If you are in a very damp area, some underlayment can increase your risk of mold or mildew. Damp basements are a good example of this type of environment. Some flooring products with attached underlayment are recommended even for rooms where moisture may be a problem. Talk to one of our flooring experts if you have questions about the suitability of a product for your installation.

You may reach us by phone at: 888-735-6679, or, feel free to send questions by email and we will respond within 48 hours.

If you want to use a flooring product without an attached underlayment, you can install a vapor barrier first, and then add your underlayment layer. Some foam products have a built-in moisture barrier. Or, you can use a rubber underlayment product directly over the subfloor to help minimize the chances of the moisture impacting your new flooring. The rubber provides sound absorption as well, and the recycled rubber underlayment is an environmentally responsible solution.

Note: Cork is not a good choice for wet environments as water may damage it. So, while cork is great for sound absorption, is mold and mildew resistant, and has insulating properties, you will want to avoid using it in basements, kitchens, bathrooms and laundry rooms.

Uneven Subfloor

If you have an extremely uneven subfloor, underlayment may help create a better final surface. Most underlayment is 2-3mm; but, in cases where you have nicks and imperfections in the subfloor, thicker underlayment may prove beneficial.

Noisy Areas

Long halls with hardwood surfaces can be extremely noisy, as can living rooms with high ceilings and no draperies. Underlayment can help reduce the amount of noise as it provides another layer of material to absorb the bouncing waves. Foam, rubber, and cork all have great noise cancelling properties.

Heat and Cold

Slabs and concrete basements both are known to hold in the heat and cold. Underlayment can add a layer of insulation between the concrete and flooring, helping reduce your energy bills.

How to know which underlayment (if any) to use

Flooring manufacturers typically note which types of underlayment are appropriate for their products and their warranties may indicate instances where installation choices (such as type of underlayment and/or adhesives) may void the warranty. If you cannot find this information, we can some general rules of thumb. But, it is best to check with an expert if you are unsure how to proceed. The flooring experts at are happy to help you to ensure you have the best outcome for your new flooring installation.

Rules of Thumb

  • Never use rubber or rubber cork underlayment under vinyl flooring as it can causing staining. Felt, foam, and cork are usually safe; but, check the manufacturer's instructions and warranty information, or reach out to our flooring team before purchasing your underlayment.
  • In most cases, whether you use underlayment or not, you may want to use a moisture barrier. Check the manufacturer's instructions and warranty information to be sure.

How to Install

  • If you are installing planks, roll out your underlayment in the opposite direction (perpendicular) to the direction your planks will run. Ex: If your planks are running north and south, lay your underlayment east and west. If you are installing square tiles, the direction of the underlayment is not important.
  • You will need to tape the strips of underlayment together at the seams by butting the seams to each other and applying the tape across the two sides to hold the strips together. Do not overlap the underlayment.

Final Notes

If your flooring comes with an unattached underlayment, do not lay an additional layer of underlayment down as you may damage your flooring. You may, however, still lay a layer of moisture barrier (vapor barrier) between the subfloor and your new flooring. As always, if you have any questions, please don't hesitate to reach out to one of our flooring experts. We are here to help!

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