Question

Can a cork floor in the basement hold up if there would be excess water?

Asked by Lynne Hamm
Honey Brook, PA

We would like to put a cork floor in our basement but worry about chance of excess water entering the basement. If this would happen and we shop vac it up would the cork dry out, or need to be replaced.

Answer

This is a great question because the common notion about cork is that it might mold and mildew if it gets wet. Mold and mildew will grow as long as there is moisture and food.

  • However, cork poses a serious challenge to mold growth because of its near impermeability.
  • Cork is hydrophobic which means it is difficult to wet.
  • One cubic inch of cork is said to contain millions of tiny cells of suberin which is a gas that helps insulate and  protect cork from physical or biological intrusions. It not only resists moisture but it also is  resists fire and denting.

Generally speaking it is difficult for mold to grow on the surface which is why cork has been used as stoppers in wine bottles for centuries. Have you ever seen mold grow on a wine  stopper? No. How about a cork fishing bobber? Ever see a moldy one? Nope.

Cork flooring is an engineered product

We don't want to give the impression that you can put your cork flooring underwater and nothing will happen. Most cork flooring is an engineered product that has a high density  fiberboard (HDF) core that is made of recycled wood fibers.

  • While most companies use an  exterior grade HDF, the best ones impregnate it with wax around the perimiter.
  • Even with this, it the HDF core is subject to mold in the presence of excessive moisture. 

The surface of most cork floors is typically coated with a polyurethane or acrylic finish. While these are very durable and long lasting under normal foot traffic and normal damp mopping, they will lose adhesion if they are left under water for long periods of time. 

Falling Water

Having said all this, it is only fair to provide an example of one of America's greatest architects, Frank Lloyd Wright. Two years ago my wife and I toured his famous Falling Water home in Pennsylvania. We were surprised to see the original cork used on the floors, walls and inside the showers of almost all six bathrooms. Considering that this home was built in the 1930's, what was really shocking was that there was no evidence of mold or mildew anywhere.

I am fully aware that this is a historic home and is probably cleaned weekly, but the fact that Wright used this product in the frist place gives one confidence that this product will hold up in damp conditions.

Comparing cork's performance to bamboo and linoleum 

Here's one more story that is worth mentioning. Our company typically displays at trade shows and one year the venue was outdoors in a quanset hut in August. The temp was about 95 and the humidity was about the same. Everyone was perspiring and the concrete floors were so wet you could see pools of water everywhere.

We had three types of flooring displayed directly on top of this floor; bamboo, linoleum and cork.

  • The bamboo and linoleum were covered with water and the cork was dry as a bone.
  • The architects and builders that visited our booth could not believe their eyes when we pointed out how dry it was.
  • We reasoned that the thermally insulating quality of cork actually blocked the cold concrete from transferring through and condensing on top of the cork.

It was a real experience that taught us some lessons and helped us sell cork that day.

Can cork hold up?

Back to your question: Cork generally does not get wet as it seems to shed moisture very well.

  • But under prolonged contact it might absorb a small amount.
  • Can it be dried out? I certainly believe it can dry out with fans, heaters or dehumidifiers. 

I would spend some serious time and attention on preventing this moisture problem in the first place

  • Should you use your cork flooring in a damp basement, I would still advise using moisture barriers such as 6 ml plastic underneath the flooring to help control excessive moisture.
  • In the event of excessive moisture you should try to mitigate it with ventilation and dehumidification.

Non-toxic penetrating concrete sealers such as GBS Penetrating sealer are helpful as are good crack sealants such as M-1 made by Chemlink.

If basement moisture is a persistent problem, you may need to look at the drainage and landscape around your home. While excavation may be costly, it will avoid other more serious problems with your foundation.

Further questions or comments write to: info1@greenbuildingsupply.com or call 800-405-0222.

 

For more information:

Read "I just finished remodeling my basement. Can you help me choose mold-resistant flooring?" a Q&A answered by Mary Cordaro.

Tagged In: basement flooring, basement moisture

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