Question

I just finished remodeling my basement. Can you help me choose mold-resistant flooring?

Asked by Meryam Sheriaty, Baldwin, NY

I just finished remodeling my basement but cannot decide about flooring. Is tile safe for kids? Should I use Marmoleum, or will mold be a problem? Please help.

Answer

Mary Cordaro

Answered by Mary Cordaro

Southern California Areas, CA

Mary Cordaro, Inc.

February 19, 2009

I'd like to address the whole issue of "finished basements" first. Unfortunately, sooner or later, finished basements almost always end up moldy-smelling, and if you smell mold, you have mold, even if you can't see it.

  • Basements are built below grade, and so moisture vapor from the earth is constantly rising up from below, through the materials and into the basement space.
  • The amount of moisture vapor will increase when the water table in the ground below your house is higher.
  • To make matters worse, rain and irrigation water around the basement may add chronic sources of water intrusion, in both liquid and vapor form.
  • Unfortunately, no amount of waterproofing or drainage will be 100-percent fail-safe regarding moisture and resulting mold in a finished basement, without a high degree of building-science expertise and planning during the design and construction phases of a building project.

If your basement materials are breathable, allowing moisture to pass through, and if those materials don't provide yummy food for mold, you may be able to prevent a moldy-smelling basement.

  • For example, unfinished concrete-block walls or concrete walls finished with plaster instead of drywall are two options for allowing good vapor transmission.
  • But if you use materials that mold loves to eat (for example, the paper on the back of drywall, or the jute backing on natural linoleum), then you could end up with an even bigger mold problem, even though you are using green materials.

That was a long way of saying: don't add to the problem by using soft or resilient materials on your basement floor. In my opinion, there are only three safe flooring options for basements: concrete, stone, or glazed ceramic tile.

  • If you use nontoxic installation materials, keeping in mind the possibility of moisture from below, you will not only be avoiding flooring that could trap moisture vapor and feed mold, but you'll have a safer floor for your children. 
  • If you choose not to cover the concrete, you might consider a wonderful service called RetroPlate for mechanically polishing concrete. The look is really gorgeous.
  • Prescriptions for a Healthy House, a book written by two Bau-Biologists (one of whom is an architect) and a holistic medical doctor, contains suggestions for nontoxic installation of stone and ceramic-tile flooring. (Note: If you are severely chemically sensitive, you may or may not be able to tolerate the materials listed in the book.)
  • For an overview of the pros and cons of different stone and tile products, read GreenHomeGuide's "Green Buyer's Guide to Stone and Tile."

Finally, you may use natural, nontoxic area rugs on your tile or concrete floor, but avoid dusty types like sisal, or rugs with permanent chemical treatments such as moth repellent. For better moisture "transmission," it's best not to use any carpet padding or underlayment. Clean the rugs and air them out in the sun a few times a year.

 

For more information:

Read Shannon Demma's Q&A "Should we install cork flooring in our moisture-prone basement?"

The website of the Building Science Corporation offers free articles with guidelines for properly isolating and ventilating your basement—and for controlling perimeter drainage to mitigate exterior sources of moisture.

Tagged In: basement flooring, basement moisture, basement remodeling

Do you have a question about greening your home? GreenHomeGuide invites you to Ask A Pro. Let our network of experienced green building professionals – architects, designers, contractors, electricians, energy experts, landscapers, tile & stone specialists, and more – help you find the right solution.