Cork Flooring Buyer's Guide:
What it is, how it's made and how to choose the right one for you
Cork flooring is perhaps one of Nature's greenest miracle floors. Made from all natural and renewable ingredients, cork floors are highly versatile,
beautiful and sustainable. They're priced about the same as most hardwood floors, from $3.99 to $6.99/SF; plus natural cork flooring is a DIY floor that's easy to install, easy to maintain and very long lasting.
The number #1 reason people like cork flooring is because it feels soft but firm to the feet, and is very quiet. The minute you step onto a cork floor your knees and back relax. You'll love the feeling of cork flooring against your body and the quiet insulating qualities it provides whether you stand in the kitchen for hours, practice yoga in your rec room, living room or bedroom, or just want to sit quietly in prayer or meditation.
Fact: Cork can last from 50-75 years in most applications.
What makes cork so special?
Here a few of its amazing attributes:
Highly compressible and resilient
Excellent thermal and sound insulator
Naturally resistant to mold and mildew
Warm to the touch
Naturally resistant to fire
Hypoallergenic and insect-resistant
Stable in various temperatures
Highly versatile with not just many, but with hundreds, of uses
Read below for the incredible story about cork.
Where does cork come from?
Cork comes from the bark of the cork oak tree which grows in the forests of Mediterranean countries. It's truly one a nature's miracle products renewing itself over and over again. The largest concentration of plantations are found in Spain and Portugal which were founded by the wine industry centuries ago. After 25-30 years, a new cork tree develops a thick bark which is about 2" thick. Skilled farmers with special tools carefully peel off about ½ of the bark. This does not hurt the tree; it all grows back again in 8-12 years and the process begins all over.
Fact: One cork oak tree yields 50 harvests over its useful life of 300-500 years. That supplies thousands of cork floors! Compare that to most hardwood flooring which requires killing the trees, and only a few floors and you'll see why cork is one of the most sustainable products available.
The bark is then cut into large uniform sheets 4'-5' long x 2'-3' wide. They're carefully transported to a mill where thin layers are veneered off the surface. Right beneath the outer bark layers are the most dense, while the inner layers are softer and less dense.
The cork patterns that you see on a cork floor come directly from the grain pattern of the veneer. Just like the grain of oak is different from maple or walnut, so there are different grain patterns of cork. These veneer patterns appear on the top layer of most cork floors.
The bark of the cork oak tree was designed by Mother Nature specifically to protect the tree during its lifespan. Not only is the bark inherently fire retardant to protect the tree from forest fires, but it's also resistant to extreme temperature changes prevailing in those regions, as well as resistant to more than 38 species of insects including the termite, and to the development of microbes.
The properties of cork are derived naturally from the structure and chemical composition of the inner cells. For example, each cubic centimeter of cork's honeycomb structure contains between 30 and 40 million cells! It's this unique cellular structure that gives cork its innate characteristics, and each of these cells contains suberin, a waxy substance that gives cork its resistance to insects, mold and mildew.
There are hundreds of different uses for cork such as bottle stoppers, floats for fishing nets, women's purses, soles of shoes and sandals, and even
furniture. In 1891 an American, John Smith, discovered that it was possible to produce agglomerated cork, opening a new range of applications such as wall tile, flooring, and underlayment. The agglomeration process involves gluing small pieces of cork together to form larger pieces in various shapes and sizes.
Cork floors have been popular in Europe since the turn of the 20th century and can be found in many prestigious locations such as the Library of Congress, the Mayo Clinic and Plummer Building, the offices of several Fortune 500 companies, several churches and museums, and the Frank Lloyd Wright Fallingwater residence.
Recently, with improved technology, an array of new patterns and colors have become available to meet the demands of today's design trends.
Cork flooring: floating planks and glue down tiles
How is cork flooring made?
Originally, cork flooring was made in the form of a ¼" thick tile: 8" x 8" or 12" x 12". These tiles were made of solid cork and glued down to the subfloor with adhesive. They were also glued to walls for decoration. The finish was mainly oil and wax. Many people report that these original tiles are still going strong even after 75 years or more! Others have complained that the edges have curled up or the cork has dried out and become brittle and very worn out.
Since 2000, cork has advanced considerably as a resilient floor covering. Not only has the finish improved, but the way it's installed has also changed significantly. Today, most cork flooring comes in two basic forms: engineered floating floors and solid tiles.
Engineered floating floors - 3 layers
Top layer - veneered cork (1/16" to 1/8")
Middle layer - high density fiberboard (1/4")
Bottom layer - agglomerated cork (1/16")
Styles of floating floors:
Panels: 12" wide x 36" long - most common
Strips: 5" wide x 48" long - newer wood look
Squares: 12" x 12" or 18" x 18" - newer travertine stone tile look
Floating floors versus glue down tiles
Engineered floating cork floors have literally taken over the cork flooring market in the last 15 years for several good reasons:
Easy DIY installation - no professionals needed
No glue required - no nasty fumes
Less subfloor preparation
More styles to choose from
More stable - no edge curling
Better finishes for easy maintenance
No initial sealing required
Numerous colors and designs:
Traditionally, all cork was one natural color of light tan, with darker elements throughout. Today, cork flooring is made in numerous colors that involve staining the surface layer. These stains look nice and unique, and can enhance the appearance of any room. However, there are some drawbacks.
Most notably, if the floor is scratched or gouged deeply, the natural cork color will appear below and contrast with the surface color. This will require special colored touch up which is not often easy to find. Cork manufacturers typically don't sell matching stains in a kit to help you out, so you have to find them on your own. Also, lighter colors such as white tend to show the seams more easily which detracts from the overall look. These are not serious, but they should be understood up front before purchasing.
The natural cork colors (i.e., not stained) are by far the most popular because:
The warm colors blends with most cabinetry and furniture
They hide dirt extremely well
They hide the seams extremely well
Which design is best?
When you begin looking at all the intricate designs it can be overwhelming. Some designs are busy, some are quiet, some are plain, some resemble wood or travertine, and some melt into the room beautifully. Looking at small samples are very helpful, but you need a good imagination to envision how it'll look in your home.
Generally, we've found that the color is more important than the design because the design tends to blend into the color, especially when seen at broad angles and in dim light. If a particular wild design excites you, then go for it. If you're conservative, however, then pick something neutral and quiet, and you will be safe. It also depends on the lighting and what angle you're viewing it from. In our experience, the natural cork color (unstained), along with almost any style, works very well in most homes. But get some samples and try them out.
What about maintenance?
Many people are concerned about the finish of a cork floor. That usually means moisture, kids and dogs. Regarding moisture, we have discussed how suberin naturally protects against moisture. In addition, cork manufacturers have developed polyurethanes, UV-cured acrylics, and proprietary blends that hold up extremely well against moisture and abrasion. As a consequence, there are few complaints with cork flooring - and many manufacturers now offer wear warranties that extend from 15 years to a lifetime.
Cork is used in wine bottles and as fishing bobbers without becoming moldy. In his internationally famous home, Fallingwater, Frank Lloyd Wright used cork on the floors, on the walls and inside the showers of several bathrooms. See amazing photo below. This is the original bathroom created in the 1930's. There's no mold anywhere on the cork.
However for demanding applications such as kitchens and other high traffic areas like entryways or hallways, you may want additional protection. In these cases we recommend sealing the floor with a non-toxic polyurethane such as AFM Safecoat Polyureseal BP.
Regular maintenance requires only sweeping and damp mopping. If your floor starts to show signs of wear, a new coat of polyurethane will rejuvenate the floor. A properly maintained cork floor will last for decades.
Cork has also become a popular underlayment to reduce sound and to improve thermal efficiency. Cork underlayment generally comes in 1/8" to 1/4" thick rolls, or in 1/2" thick large sheets 2' x 3'. Cork underlayment has become the product of choice beneath ceramic tile, hardwood flooring, carpeting, and other solid surface floors, mainly in apartments and condos.
What to look for in a cork floor
Cork flooring is one of the best green floors no matter who makes it, right? Wrong. While cork flooring may appear similar from one manufacturer to one another, the secret of their differences usually surfaces months later in performance, indoor air quality and maintenance.
Let's take a deeper look into how cork is manufactured to understand some of these differences.
Density + resiliency = durability:
For the top layer, manufacturers use a cork veneer taken from the outside portion of the cork bark because it's older and denser than the inner portion, which is younger and softer.
The inner portion of the cork bark is ground up and used on the bottom of the plank and acts as a built-in underlayment.
Densities are measurable and labeled by some manufacturers - the higher the density the better. There may not appear to be big differences but careful examination and testing will reveal some cork is softer and less resilient than others, while some are much more firm and dense providing a more durable product.
It's well known that cork has a great 'memory' or impact resistance. Try digging your fingernails into some cork and you can easily dent it; but after about an hour or so, most of the dent will have disappeared. The denser the cork, the more cells of suberin, and therefore the better the performance.
There are also differences in overall thickness of both top and bottom layers. Hold two pieces of cork flooring back to back and you will easily see these variations. Thicker cork on the top and bottom is preferred but it does not always mean it's denser. You have to test them yourself or check the specs.
Adhesive are used in between each layer of cork as well as between the granules of the backing. As most cork comes from Europe, the standards for adhesives and their emissions are usually very high compared to the US. Most manufacturers exceed E0 and CARB 2 standards for urea formaldehyde, however, not all are third-party certified. You have to check as everyone now says their product has no added formaldehyde.
There is also competition from China for cork flooring. Unfortunately, the standards there are questionable. Therefore, to be sure you're getting products that are safe, insist on seeing independent certifications to verify a manufacturer's claims.
High density fiberboard core
All cork floating flooring uses a high density fiberboard (HDF) in the middle section of the panel. Some have added urea formaldehyde and some don't. Some are made from FSC certified wood fibers that have been recycled and some are not. FSC stands for Forest Stewardship Council, an independent world wide organization that certifies sustainable harvesting, social equity and environmental stewardship. We recommend any HDF material that is FSC certified, has no added urea formaldehyde, exterior grade, and has been impregnated with wax all around the perimeter.
Ultra low VOC finishes
Here is where some major differences may appear. Before modern high performance finishes existed, natural oils and waxes were all that was used. For
hundreds of years natural linseed oils and beeswax worked very well. If you visit older court houses or libraries you'll find cork flooring still going strong with oil wax finishes.
While most new finishes are UV-cured in the factory, some may still off-gas for weeks or months after installation. This information should be available in the MSDS of any reputable manufacturer.
Commercial finishes are now available for cork which are extremely tough and will extend the life of the cork for years before recoating is necessary. While this is practical and useful, the feeling of the cork on your feet is not the same, nor is the odor.
If you're chemically sensitive or have allergies, it's best to test a sample first for its effects. (link to testing formaldehyde and VOCs)
Most residential warranties are for structural integrity which means the top, middle and bottom layers won't delaminate. Some include a warranty for the finish on the top layer which is ideal, although they rarely cover normal wear and tear. They usually cover any defect in the finish such as peeling, pitting or being too thin. Most cork brands warrant their products for 10 years and some are for a lifetime, which is excellent. Commercial warranties are usually much less, usually around 5-10 years, but with new finishes come longer warranties extending up to 15 years.
Keep in mind, if you have large dogs or kids with skateboards, a residential or a commercial warranty will not cover abuse. In general, deep scratches and gouges can be repaired with wood putty, and the natural color variances hide them very well. Same holds for hiding dirt.
Bottom line: go for the best warranty but understand that all flooring warranties only cover manufacturing defects and never pay for removal or
installation costs unless you can prove negligence on the part of the manufacturer.
Note: We've been selling cork for 17 years to hundreds of customers without a single warranty claim.
Cork tiles (solid 1/4" cork) are glued to a perfectly smooth level subfloor. However, cork floating floors (planks, squares, large or narrow tiles) can be installed over most wood or concrete subfloors. Most brands work in the same manner. They can even be installed on top of existing vinyl or laminate flooring. (please refer to the manufacturer's installation guidelines)
The edges of cork floating flooring are designed to click together; no glue is required. With only a few tools required, installation is relatively easy for most do-it-yourselfers. Most rooms can be completed within a few hours.
Consider a professional if:
you're not handy with tools
you want a flawless looking floor
your subfloors are uneven and need prep work
you don't have the time
your mother-in-law or father-in-law is moving in
your spouse doesn't exactly love your carpentry
Consider doing it yourself if:
you have some basic skills and own some tools
your subfloors are relatively even
you have time to do this properly
you need to save money
your spouse is not fussy
Where is cork flooring installed?
Cork is commonly used in kitchens, bathrooms, rec rooms, dens, living rooms or bathrooms. The more cork you use, the better it looks. Large areas of cork really look much better than a small area here or there. This is true of most flooring.
What about basements and bathrooms?
Cork and water get along very well which is why it's used in wine bottles and on fishing bobbers. However, the finishes and adhesives are not designed to be underwater for long periods of time. The high density fiberboard core on most cork floating floors has been impregnated with wax to prevent absorption of moisture. Make sure your cork flooring has this feature.
If you have young children we don't recommend using cork in their bathroom. If your basement floods every so often we don't recommend that either. However, dry basements are fine and so are bathrooms where constant moisture is not an issue and good ventilation is available.
What about radiant-heated floors?
Yes, cork works fine here too. Remember, radiant heat is infra-red which transfers through just about any material including concrete, wood, glass, metal, insulation, etc. Cork is a thermal insulator, and a good one, but it does not stop infra-red heat from penetrating through. We have worked with dozens of customers with radiant-heated floors that all say 'no problem, it works fine.
Which style or pattern to choose?
Cork comes in busy patterns and quiet patterns. Depending upon your taste and the style of your home or office, don't be
afraid to experiment with some wilder ones as they rarely look that wild after installed on the floor. Patterns is a misnomer as they are never repeating but always random.
Regarding styles such as floating plank vs squares vs large tiles or narrow tiles: The standard planks (12" x 36") or squares (12" x 12") have a square edge detail that provides a more uniform smooth floor. The large tiles and narrow tiles have beveled edges, and create a more traditional look. You have to see several pieces together to really get the feel of them, but they do have their place.
How is cork flooring maintained?
Caring for cork flooring is similar to caring for hardwood, linoleum or bamboo flooring. Regular dusting and damp mopping is all that's required to keep it in good shape. Most manufacturers plead with customers not to flood with water as repeated flooding will cause the edges to swell. As with all flooring, avoid harsh cleaning chemicals and excessive water. If maintained properly, cork flooring should last as long as your home. We recommend: Bona Kemi Floor Cleaners (link)
In case repairs are needed, normal wood putty will work for most deep scratches or gouges. In high traffic areas, you may want to apply a couple of coats of polyurethane to extend the life of the finish. We recommend: AFM Safecoat Polyureseal BP for the finish.(link)
How much extra should I order?
In general, 5-10% extra. This depends upon the size and shape of the room(s). Large square rooms with no closets will have the least amount of waste. Add closets, hallways, L-shaped areas or curved or angled walls and your estimates should include 10% extra.
While cost may be a factor, getting an extra box or two is always a prudent idea. This is true for all flooring. As retailers since 1991, it's very common for us to receive inquiries for old outdated designs or patterns of flooring to be used in a new addition or for a damaged area. Customers spend hours searching high and low for a few extra planks that should have been purchased with the initial order as an insurance policy. After all, flooring is a large investment. Isn't it worth protecting?
Want to learn more? Go to the Green Building Supply Learning Center to browse our entire collection of articles, FAQs and white papers for every product. How to Buy a Green Floor (link) has more details about installation.
Need help measuring or making decisions? Call one of our experts at 800-405-0222 and we'll be happy to help you choose the right floor for your application and budget.
Beautiful, soft, warm, non-toxic, renewable, insulating and sustainable, cork is clearly one of the best green floors available. Give it a try in one room and you'll see why.
This category was written by Joel Hirshberg