I’m looking at a parquet floor, as one does, admiring the rich brown hues and subtle contrasts in the grainy patina, yet feeling a little confused. This floor is slightly bouncy and warm underfoot; it gives a little, compared with oak, which, much as I adore it, does tend to be hard and cool. What is it?
It’s cork, and before you turn away with a head full of visions of corduroy flares and Bay City Rollers tunes, it is a million miles from Seventies cork floor tiles, which looked warped and tired even before being laid.
Cork comes from the bark of the Mediterranean cork oak, and new processing techniques mean that 21st-century cork interiors include carpet underlay, upholstery covering, wallpaper, thermal insulation and those parquet-style floors. But the best thing about cork is that it is probably the greenest building material available. Not only is it a recycled material from a renewable source but its use protect s the last remaining habitat of the Iberian lynx, the Iberian imperial eagle and other endangered species. It also provides jobs for thousands of Portuguese and Spanish cork workers .
Yet less than 10 years ago, ecologists were warning that the remaining Mediterranean cork forests were dying out. The vogue for screw-top wine bottles was decimating the cork stopper industry, the raison d’être for their conservation.
However, a combination of cork forest farmers improving the reliability of cork wine stoppers and increasing acreage of cork forest becoming FSC-registered has meant a renaissance . Bark is harvested every nine years and each tree lives for up to 200 years.
Cork tiles and wallpaper come from waste material produced in wine-stopper manufacture. Cork’s natural insulation properties have inspired researchers to view it as an alternative to synthetic materials, such as polyurethane foam. It has extremely low thermal conductivity: walls lined with cork lose heat slowly. In tests, it outperforms breeze blocks, bricks, plasterboard, cement and plywood.
“Cork was used quite extensively in the house-building industry until the Fifties, when oil-based products out competed it on price,” says Allan Creaser, director of Cork Insulation, a company at the forefront of cork research for buildings. “It is now coming back into vogue because it’s natural and is the only completely carbon negative building material.” At £23 per square metre for 100mm thick boards it is more costly than synthetic insulation, but Allan says that overall, the final difference is only slight, as cork does not require finishing.
Architect Susan Venner is one of the first home owners in the country to use cork cladding on a period building to try to reduce heat loss. Dark brown 180mm-thick boards cover the north-facing wall of her Victorian terrace in south London. “It has performed brilliantly,” she says. Her house is monitored by University College London’s Bartlett Faculty of Research for the Built Environment. “Air pockets in the cork trap heat and although it gets wet when it rains, moisture does not penetrate into the lower layers and just dries out again when the rain stops. It’s naturally mould-resistant so it doesn’t rot either.” Heat loss through the walls has been reduced by a factor of 10 .
The National Trust is also using cork insulation in its refurbishment of the stables at Morden Hall Park in Surrey.
Cork is a super-insulating alternative to conventional foam underlay, blocking out cold air from underneath floorboards and still allowing wood to breathe. At £1.50 a square metre, it competes well on cost and does not disintegrate as foam does.
Techniques to produce ever thinner layers of cork have resulted in a fine soft leather, washable at 30C, with a beautiful natural grain that lends itself to upholstery; slightly thicker layers create natural-look wallpapers. “It’s so eco-chic it’s unbelievable,” says Ruary McGregor, of Jelinek Cork. “The beautiful thing is that there is no waste at all in the manufacturing process – every grain is used.”
Useful information:
Cork leather, wallpaper and flooring: jelinekcork.co.uk
Insulation: cork-insulation.com
Details of WWF’s cork forest projects: mediterranean.panda.org
