Installing Cork Underlayment

In 2014 the number of inquiries I received for the use of Cork Underlayment for sound reduction grew dramatically. Sound reduction for multi-family dwellings and apartments continues to grow and grow.

Cork is an excellent choice for sound reduction and offers many advantages:

  • Environmentally safe – rapidly renewable
  • Excellent in-room and below-room sound reduction
  • Thermal insulation – warm under foot
  • Will not degrade or compress over time
  • Anitmicrobial – great for people who suffer from allergies and asthma
  • Resistant to moisture, mold and mildew
  • Low height requirement – available in 1/8″, 1/4″ and 1/2″
  • Lays flat – available in sheets and rolls
  • Easy to install under all types of flooring products

Cork Underlayments come in a variety of thicknesses depending on the floor covering application.

2 mm, & 2.5 mm Cork Underlayment – generally are used for under glue down and floating Engineered Hardwood, Laminate, & Luxury Vinyl Tile and Plank. Glue down Fiberglass and Felt- backed sheet floors. VCT, Vinyl Enhanced Tile, Linoleum, Homogeneous & Heterogeneous Sheet and Tile, Rubber Sheet and Tile. Glue down Luxury Vinyl Tile and Plank.

3 mm, 5 mm, 6 mm, & 10 mm Cork Underlayment – Glue down and floating Engineered Hardwood, Laminate floors

1/2′′ Cork Underlayment – Ceramic Tile, Glue down and floating Engineered Hardwood, Laminate floors.

Listed above you may have noticed that only glue down and floating Hardwood is recommended, not nail down Hardwood. Never mechanically fasten through any sound underlayment barrier, as this severely diminishes the acoustical performance of the entire sound rated floor system. Sound will travel through the fastener and transmit it to the area below. For instance, a 12′ x 12′ room that is having a 3-1/4′′ wide Engineered Hardwood floor nailed/stapled down every 4′′ will have 1,595 nails/staples protruding through the sound underlayment barrier. If someone insists on a nail/staple down application, an option would be to loose lay or glue down the sound underlayment barrier underlayment over the subfloor. A double layer of 3/8′′ plywood, glued and screwed together at right angles is then laid over the sound underlayment barrier, and the wood floor is then nailed into the plywood, not the through the sound underlayment barrier to preserve the integrity of the sound rated floor system.

I receive calls from dealers asking for products that meet a specific IIC rating. IIC (impact insulation class) IIC measures a floor/ceiling assembly’s resistance to the transmission of structure-borne or impact noise. IIC is measured in terms of sound impact, or how well sound vibration travels through a floor, to the room below. Before giving them an answer, there are many subfloor/ceiling factors to consider that can affect the IIC rating. Many sound reducing membrane manufacturers publish ridiculously high IIC rating, but do not give any specifics as to how and what the tested flooring, subfloor, ceiling, insulation system is, which can make a huge difference in the IIC rating. So before asking for a product with an IIC rating, you will need to know what the flooring, subfloor, ceiling, insulation system consists of. Different systems will provide different IIC numbers.

Cork Underlayments may be installed floating or fully adhered depending on the type of flooring installation and what the Cork manufacturer recommends. An advantage Cork Underlayment has over gluing down some foam underlayments is that I do not need a special adhesive to glue the foam down and then another adhesive to glue the flooring to the Foam Underlayment. Generally the adhesive to glue the flooring down, can be used to glue the Cork Underlayment down.

Glue Down Cork Underlayment

  1. Test the subfloor for moisture prior to the installation of the Cork Underlayment.
  2. If excessive moisture is present (normally 5-lbs. or less with a Calcium Chloride test) in the subfloor, corrective action must be taken by using a moisture retarding system.
  3. Install the a perimeter isolation barrier vertically around the perimeter of the entire floor including any openings or protrusions such as electrical boxes, heating ducts, cold air returns, columns or pipes in the subfloor installation. The perimeter isolation strip MUST be installed prior to the underlayment being installed. By not installing the perimeter isolation, sound can travel out and down through the perimeter.
  4. Cut and position the Cork Underlayment to the space to be covered.
  5. Butt the Cork Underlayment against the perimeter isolation barrier.
  6. Apply Adhesive to the subfloor and roll in both directions with a 75 or 100 pound roller. For specific recommendations, consult the Cork Underlayment manufacturer.
  7. Cover the entire room, making sure the sheets are tightly butted together, without gaps. Rolling the floor area in both directions using a 75 or 100 pound roller. Never mechanically fasten the Cork Underlayment to the subfloor, as this will severely diminish the acoustical value of the product.
  8. The Cork Underlayment should cover the entire floor area without gaps and be securely bonded with the joints of the Cork Underlayment tightly butted.
  9. Allow to dry over night, and install flooring the next day following the flooring manufacturers guidelines.
  10. If baseboard or shoe molding is to be installed, leave a minimum 1/8” gap between the flooring and the bottom of the shoe or baseboard. This gap must be filled with an Acoustical Grade Sealant.

Below are Cork Underlayment Suppliers JJ Haines deals with:

The Flexco/Roppe AcoustiCORK CorkPLUS 250 covers the needs of most commercial floor coverings in need of sound reduction and comes with a Limited Ten (10) Year Residential Warranty and a Limited Five (5) Year Commercial Warranty.

Approved for Use with (Always Check with Flooring Manufacturer Prior to Use for Approvals)

Luxury Vinyl Tile & Plank
Solid Vinyl Tile & Sheet (Heterogeneous & Homogeneous) Fiber & Felt Backed Vinyl Sheet
Rubber Tile & Sheet
Vinyl Enhanced Tile
Vinyl Composition Tile
Floating / Loose Lay Floors



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