Green Underlaying Materials for Floating Floors

Sustainable underlay options include wood, cork, and wool.

Posted by Steve Graham | Oct 15, 2009
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Sustainable flooring should start under your floorboards. There are plenty of green underlay options. Be sure to consider toxicity, recycled content, and insulation when choosing what to place under the floors.

First, don't try to reduce your use of "stuff" by skipping the underlay. Your frugality might be counterproductive if the floor requires quicker replacement. The underlay can keep moisture and mold off the floors. Bamboo, cork, laminates, or other floating floors may also develop cracks and gaps and wear down faster without a soft cushion. Finally, underlay can block noise and make flooring more flexible, so it is easier on the knees.


Nasty chemicals are often the easiest way for manufacturers to create a flexible, mold- and noise-resistant insulator. For the planet's health, avoid toxic chemicals and minimize volatile organic compounds. For your health, look for formaldehyde-free, antimicrobial and hypoallergenic materials. Don't assume a natural material, such as wool or wood, is pure. It may be chemically enhanced to prevent mold and moisture. On the other hand, some synthetic rubber and polyurethane products may be formulated with minimal VOCs, and could be safer for allergy sufferers.

Recycled and Renewable Content

It can be hard to find underlay with large amounts of recycled content, but CoraZorb Green is a widely applicable option. The material is 92 percent recycled rubber. It is designed for use with a thin-set mortar under tile, but can also be used under hardwood and floating wood floors. It is moisture resistant and designed for easy installation. The next best thing is a renewable virgin material, and a few options are available.

  • Cork underlay certainly fits the bill. Cork is a rapidly renewable bark, and stripping the bark is considered beneficial for the tree, extending its lifespan. Consider putting a soft cork underlay under a solid cork floor.
  • Likewise, try wood under wood. Redupax is designed for use under floating laminate and engineered wood floors. It is primarily compressed wood certified by the Forest Stewardship Council. Note that the manufacturer does not promote Redupax as VOC- or formaldehyde-free.
  • Another option for floating-floor underlay is a 100-percent sheep wool covering. Remember, though, that wool is a common allergen.
  • SoundStop Underlayment is mostly made from wood and sugarcane fibers sustainable sourced close to the manufacturing facility, and glued together with a formaldehyde-free vegetable starch binder.


Our insulation advice may seem counterintuitive. On energy-efficient radiant heat flooring, ignore all the standard sustainability advice about maximizing insulation R-values. You need more heat to come through the floor, so lower R-values are better. On the other hand, maximize sound insulation no matter the flooring or sub-floor. Wool and cork block both sound and heat, so they are not a great option for radiant heat applications, but highly recommended for other floors.

Don't forget to consider sustainability when choosing an underlay for floating floors. Cork, recycled rubber, and wool are among the many green flooring underlay options.

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