F03B2 Cork Selection

F03B2 - MATERIAL GUIDES - CORK SELECTION

F03B2-1 General & Technical Information
F03B2-2 Cork Flooring
F03B2-3 Cork Flooring installation
F03B2-4 Cork Flooring issues

Preface:
This study guide provides a brief and simple overview for the selection of "cork" as a floor covering material.

1 • GENERAL AND TECHNICAL INFORMATION

.01 Cork flooring manufacturers and suppliers have samples as well as technical information on their products available to the design authority. Some caution should be exercised in reviewing this material so that any one flooring type can be fairly compared to another. This involves careful scrutiny of the material specifications and test data.

.02 Technical information regarding installation methods is also available from cork flooring manufacturers and suppliers in regard to their specific products. General information on product installation is also available to a degree, from Provincial Floor Covering Associations.

2 • CORK FLOORING

.01 What is Cork Flooring?

The primary or first use of the harvested cork bark is for the extraction of cork stoppers to meet the demands of the world's wine and champagne industries. The remaining cork (called "blocker waste) is then ground up and processed for use in the production of agglomerated cork and cork and rubber compounds. These materials are used in a variety of applications from construction and gaskets, to bulletin boards and decoration, and most importantly in the fabrication of flooring materials.

Cork flooring is manufactured from granular cork particles which are graded / sorted for uniformity, mixed with a binder, and compressed under heat and pressure into "agglomerated" cork which is then cut into various sizes and thicknesses. Agglomerated cork flooring is available in tile form that may have an attached backing and an engineered (laminated) plank form. Cork flooring is generally factory pre-finished but is also available unfinished for site finishing.

Because of its aesthetic and environmental appeal, and comfort under foot cork flooring may be used in both residential and commercial applications. This type of flooring, as with other types, must be reviewed in regard to its substrate, usage, and specific performance requirements.

In addition, because of its unique appearance cork flooring offers the designer a different choice of flooring and an opportunity to create a design statement. Before choosing cork flooring however the design authority must be aware of the basics of cork materials available.

Note: This unique type of flooring may be classified by some as wood flooring because of its material composition (fabricated from cork tree bark) or even as a resilient flooring because of its resilience and tile form.

.02 Cork Flooring Characteristics:

Cork's unique properties derive from its distinctive honeycomb cellular structure. In fact over 50% of cork is captive air (a 25 mm (1") cube of natural cork contains more than 200 million tiny air-filled pockets). Each of these air cells function as a miniature sound and thermal insulator, as well as a miniature pressure and shock absorber. This results in cork flooring having the following characteristics:

Insulation: As cork consists of entrapped gaseous matter, the density of cork flooring is extremely low giving the materials insulating, thermal, as well as acoustical properties. As a result cork flooring maintains an optimal floor temperature all year round and reduces sound transmission between and within rooms, creating a quieter, and therefore more peaceful environment.

Low conductivity: Cork has one of the best insulating values of any natural material, with very low conductivity of heat, sound or vibrations.

Lightness and Low Density: The cellular structure of cork makes it very lightweight, resulting in cork's celebrated buoyancy.

Impermeability: Due to the presence of suberin, an inherent waxy substance, cork is impervious to both liquid and gases. This sealing capability is not only an ideal characteristic for flooring but also for other cork materials such as gaskets and sealing rings. Suberin is also a natural insect repellent.

Durability: because of its cellular composition, cork flooring is remarkably resistant to wear and is less affected by impact and friction than other hard surface flooring material. This high friction coefficient results in a durable wear surface.

Resiliency / Elasticity: when corking flooring is subjected to pressure due to foot traffic, the gas in the cork cells is compressed and volume reduces considerably. When released from pressure, cork flooring recovers / rebounds very rapidly to its original shape. This characteristic results in a more comfortable surface to walk and stand on and also relieves strain on feet, joints, legs, and back.

Fire resistance: because it has a remarkably high tolerance to heat, does not spread flames and does not release toxic gases during combustion cork is a natural fire retardant.

Hypoallergenic: As cork flooring does not absorb dust or entrap dirt, germs or fungus it does not aggravate allergies thus actively contributing to a healthy and hygienic environment.

.03 Cork Flooring Types: Cork flooring material is manufactured in three different forms:

Cork Tile Flooring: This is the primary and original form of cork flooring available in "massive" solid cork tile or "veneer" cork tile with a composition cork base.

Cork Plank Flooring: This is an engineered (laminated) flooring assembly with a top wear layer of cork, a centre core layer of a water resistant medium density fibreboard (MDF), and a bottom balancing layer of cork for stability.

Cork Sheet Underlayment: This cork material is used for underlayments only and not as a sheet flooring.

For a full description of these flooring types refer to F03C2.

.04 Finishes: Cork tile and plank flooring is available in natural or stained form with a number of finishes available each with their own design possibilities:

Unfinished Flooring: The top (exposed) face of cork tile or plank is lightly sanded and left ready for site applied finishes (such as polyurethane, acrylic, or wax).

Pre-Finished Flooring: The top (exposed) face of cork tile or plank is lightly sanded and factory finished with a clear sealer and a number of clear polyurethane or acrylic vinyl top coats that may also have a aluminum oxide or ceramic granules added durability. Prior to finishing cork flooring units are either natural or may be stained a variety colours.

3 • CORK FLOORING INSTALLATION

.01 Installation Methods:

Depending on type of cork flooring it may be installed either glued to the substrate (typically tile form) or installed as a floating floor (typically plank form) without the use of fasteners or adhesive. The latter may require a separate underlayment under the flooring to allow it to move freely. In both cases flooring must be installed over a substrate that is approved by the flooring manufacturer.

4 • CORK FLOORING ISSUES

.01 Cautions:

Although cork floors may be installed anywhere in residential applications including kitchens, excessive moisture may affect a floor's performance. As a general rule, it must be noted that cork flooring is unsuitable for installation in rooms where wet or damp conditions prevail or where accidental water flooding may occur, such as in bathrooms, laundry rooms, storage rooms containing hot water tanks, etc.

Although cork tiles are cut to exactly the same size, one tile can expand fractionally more than another resulting in tiles of slightly different sizes. This is due to the fact that the amount and composition of cork granules in each tile is never exactly the same. This is important to understand and factor in when planning a cork floor installation. The easiest way to correct for expansion size variation is to install tiles in a staggered pattern (much the same as a running bond pattern used in brick installations) as opposed to attempting to align tile joints in a grid pattern (which is still possible but tends to be more difficult).

The durability of cork flooring in residential or commercial areas depend largely on the type and frequency of the traffic to which the floor is subjected to. When selecting cork flooring, attention must be paid to this issue. In all cases the manufacturers recommendations on type and finish of cork flooring must be heeded.

Although cork flooring is generally impact resistant it can be damaged by heavy furniture loads, by dragging heavy objects across its surface, and it can be punctured by sharp objects.

.02 Cork Flooring Warranties:

Cork flooring manufacturers offer warranties on their products that will vary from one manufacturer to another. In general such warranties include the following provisions:

Cork flooring must be installed in strict accordance with the manufacturer's instructions on acceptable substrates using manufacturer's recommended materials and accessories.

Cork flooring must be installed in interior locations only.

Any surface wear or damage is not the result of accidents or abusive conditions such as, but not limited to, damage caused by severe impact, scratching or cutting, insects, improper alterations or modifications.

Cork flooring water resistant warranty provisions are usually limited to resistance to topical water that is cleaned up immediately. Such warranties usually exclude damage caused by washing the floor (except for damp mopping), leaking appliances (including but not limited to dishwashers, washing machines and refrigerators), leaky pipes or faucets and overflow of fixtures (e.g. sinks), pet urine, hydrostatic pressure, flooding, or acts of God that result in the penetration of moisture.

Cork flooring manufacturer's wear warranties usually cover wear, staining, and fading within a specified warranty period provided that the flooring is cleaned and maintained in accordance with the manufacturer's instructions. Use of cleaning products and methods other than those recommended by the manufacturer may void any warranty claim.

.03 Caveat Emptor (Buyer Beware):

To alleviate problems resulting from the improper selection and/or installation of cork flooring, it is the Consumer's responsibility to be properly informed. Both the design professional and the cork flooring dealer also have an obligation to inform the consumer of the pertinent facts in choosing cork flooring.

One way to be assured of receiving a professional installation is to deal with reputable and knowledgeable firms who will charge a fair and reasonable price for all materials and installation services. Firms that are proud to provide a quality installation are aware that by doing so they have created one more satisfied customer who will return to purchase again or one who will recommend them to others.