This post is another installment in my series about flooring choices. Cork is a great “green” choice for those interested in a picking a sustainable and beautiful material that avoids the health and environmental problems I wrote about in “Killing Me Softly with Carpeting.”
Why Cork is Sustainable
No trees were killed in the process of making the beautiful floor shown at right! That’s because cork is actually the bark of a cork oak tree, genus Quercus suber. It can be stripped off of the tree every nine years or so without damaging the tree.
Cork oaks live up to 200 years, and their forests — “Montados” — are treasured and have been passed down through families in the Mediterranean areas where the trees grow. Most of those forests are concentrated in Portugal, which is home to 30% of the world’s cork trees and 70% of world cork production. (The trees have been grown in California, but they haven’t produced bark with the same qualities as the European trees, which come from Spain, Algeria, Tunisia, Italy, Morocco and France, as well as Portugal.)
In fact, you can feel good about choosing a cork floor, because in recent years, a flagging demand for cork — much of which was used to stopper wine bottles — has devalued the forests. As wine corks have been replaced with metal screw tops or plastic stoppers made from petroleum products, families have sold or abandoned cork forests and land, shrinking the trees’ available habitat.
That’s a shame, because the business of growing cork has been around for centuries. The first Portuguese regulations protecting cork trees were written by Portugal’s King Dinis in 1320, and cork floors have been used in churches and libraries since 1898, long before they were used in private homes.
Cork’s Natural Advantages
Cork contains a natural, waxy substance called suberin, which is not only waterproof, but also resists insects, mold and mildew. That’s great if you or you loved ones suffer from allergies. Suberin is fire resistant, and cork doesn’t release any toxics when it burns.
Cork is pleasantly springy under foot — much kinder to your back than a cement or tile floor — and because it’s filled with little air pockets, it insulates and absorbs noise. It’s also naturally flame-resistant. Structurally, cork bark is a cellular honeycomb structure of 14-sided polyhedrons; inside they are 90% air. Those qualities make it a nice choice for a kitchen.
Because cork is rather elastic, it can take foot traffic or heavy furnishings and still recover. The cork honeycomb contains about 40 million of cells per cubic centimeter, and they allow cork to be compressed up to 40% and still spring back to its original shape. That elasticity also makes cork forgiving enough to install over rather uneven surfaces. You can mount cork on top of a wood or linoleum floor, or you could also use it as an underlayment for ceramic, wood or stone.
Cork can be purchased in rolls or in tiles, and it can be mounted on walls, as well as floors. (I’m currently eyeing some beautifully colored cork tiles for a bedroom wall. The wall is cold because it’s poorly insulated and it’s on the outside perimeter of the house. That particular wall is also showing some cracks and has old, uneven plaster, so cork tile might be just the answer.)
Cork also comes in an astonishing range of colors and patterns, so it can enhance not only the tactile and audial qualities, but also play a starring role in a room’s design.
Care, Feeding and Lifespan
Cork floors, like cork trees, can be remarkably long-lived. With fairly straightforward care, your cork floor should last for a very long time. Your cork floor will be dressed with a wax, acryllic or ceramic coating, and it’s primarily this coating that you will be maintaining. (Ceramic is the most durable of these choices and UV-cured wax is the greenest.) Here’s all you need to do:
- Vaccuum or sweep weekly
- Damp mop monthly, but don’t use a lot of water
- Use a mild soap that is PH-balanced, and make sure the surface is free of grit and sand
- Avoid abrasive cleaners and oil or ammonia-based cleaning products
Downsides to Cork
You will note that the cautions above mention both grit and abrasives, and there’s good reason for that: Cork flooring scratches! The scratches usually marr the coating on top of the cork rather than the cork itself, but it’s still a problem.
Cork is soft – its Janka hardness rating is 200, harder than balsa but softer than pine. But cork is so different in character that it’s not entirely comparable. For example, cork actually has the ability to spring back and “heal” a cut so that you later can’t find it!
For this reason, you should pay attention to the durability of the coating on top of the cork. The wear finish on a cork floor may either be applied at the factory or in your home, and it’s usually varnish, oil or sealer that is hardened with ultraviolet light.
Cork is not a good choice for bathrooms because it will buckle when exposed to too much water. In addition, the darker shades can be prone to fading, particularly in sunny areas.
The Fine Green Print
The question of sustainability is always complex, and although I have extolled many of cork’s green virtues above, there is one notable drawback. The cork we buy must be shipped across the ocean, making for a large carbon footprint.
The processing of cork is fairly simple. Cork sheets or pieces are cured, boiled and pressed. Scraps are collected for reuse, so almost nothing is wasted.
But toxics can definitely come in to the equation! Some cork flooring is made with binders, finishes or substrates that contain carcinogens. I would avoid cork composition floors because cork is sometimes combined with Polyvinyl Chloride (PVC) to make a resilient flooring that looks like linoleum. But while linoleum is a green material, vinyl is not! The vinyl manufacturing process may hazardous byproducts and the disposal may leach toxins into the environment. (The U.S. Green Building Council has acknowledged “strong environmental and human health concerns” with vinyl.)
The cheapest cork comes from China, and because it is subject to very little environmental regulation, it is likely to contain toxic glues.
Installation of Cork Floors
Like pre-finished wood floors, cork floors can either be installed as “floating” floors from panels that snap together with a tongue-and-groove system, or they can be glued down. Having your floor glued down will save you on material costs, but you will pay more for labor, and it can be harder to repair a glued-down floor should you later need to do that.
Some floating floors can be installed over hard surfaces — vinyl, wood or tile — but cork needs more stability that you would get from a carpet or soft floor. If you don’t have such a surface, you will need to have a contractor install a stable subfloor.
Cost and Suppliers
The cost of having a cork floor installed in your home runs from $5 to $10 a square foot, with the flooring itself priced about $2.50 a square foot (2009 costs). The best quality, non-toxic versions are within that range. The European Union’s standards for toxics are 100 times stronger than those here, so one good, non-technical way to find a cork floor that doesn’t contain harmfull chemicals is to search out European flooring.
Here are some manufacturers and suppliers whose websites you might wish to browse:
- Duro Design Flooring
- WE Cork
- Natural Cork
- Globus Cork
- American Cork Products (cork wall tiles as well as flooring)
A Drunkard cannot meet a Cork
Without a Revery —
And so encountering a Fly
This January Day
Jamaicas of Remembrance stir
That send me reeling in —
The moderate drinker of Delight
Does not deserve the spring —
Of juleps, part are the Jug
And more are in the joy —
Your connoisseur in Liquours
– Emily Dickinson