Basement Makeover Advice is All Wet.
Earlier this week, I had a conversation with Walter Arnold, of Kelly Floor Covering in Seaford, New York. I called Mr. Arnold to discuss an ad he had sent me that appeared in Newsday, a large newspaper serving New York City and Long Island. The ad was for a local home improvement company and the headline read, Around the House: A Basement Makeover. The ad targeted people who were looking to renovate their basements in environmentally-friendly ways, and it made various suggestions for paints, wall and floor coverings, etc. About carpet, the ad said:
In carpets, opt for natural/woven/non-VOC blends over synthetic/tufted ones for lower eco-impact and more durability.
Mr. Arnold, who has more than forty years’ experience selling carpet in the Long Island area, was astounded that a home improvement professional would offer the public such bad advice. “They’re suggesting people put wool carpet in their basements,” he told me, then asked, “Have you ever had a wet wool sweater that you lost and then found again about a week later?” suggesting that before too long the basement would smell like a wet sheep. I love hearing from people about the carpet issues that concern them, and I really appreciate Mr. Arnold bringing this one to CRI’s attention.
Is using carpet in a basement a good idea or not? I asked independent carpet expert and technical consultant Lew Migliore for his views on the subject.
CRI: For some people, using carpet in a basement is a real concern, because they are afraid that the carpet will encourage the growth of mold and mildew. Are they right?
LM: It’s understandable that people might be wary of using a textile floor covering in an area like a basement, but the truth is that all carpets manufactured with synthetic fibers - nylon, polyester or polypropylene, for example - are inherently immune from mold and mildew.
CRI: How is that?
LM: To support mold growth, certain specific conditions must exist: humidity consistently above 60%, temperatures between 50 and 90°F, continued darkness, a pH of 3 to 8, and a food source. As a form of thermal plastic, carpet cannot, in and of itself, be a food source for supporting the growth of mold and mildew. Things like dirt and food that get trapped in the carpet fibers can become a food source, but the carpet alone cannot.
About the other factors that promote mold and mildew, frankly, if a building has a humidity reading that stays above 60%, there’s a lot more to worry about than the possibility of mold or mildew in the carpet. Under such moist conditions, other surfaces, like drywall, wood, and natural fiber materials will be prime targets for mold and mildew to grow on. Mold spores are everywhere – they are present in 100% of building interiors and unless moisture is controlled mold will grow – but this has nothing to do with the carpet per se.
In terms of indoor temperature, temperatures on the floor where carpet is installed are normally too cool and dry to pose a threat. The pH of carpet installed over concrete is predictably not at a level conducive to mold growth. In fact, in the forty years since carpet mills started using synthetic backing materials instead of natural fibers like jute, synthetic carpet has not generated or perpetuated complaints for mold or mildew.
CRI: What about installation?
LM: Carpet installed in a basement directly over concrete can be laid using either the direct glue-down method or a stretch-in over cushion. Virtually all adhesives used in the industry today do not support mold growth. There are also anti-mold cushions available that actually prevent the growth of mold, mildew and bacteria. Any carpet placed on these kinds of cushion is protected from potential threats that originate from beneath the carpet. Of course, moisture that comes up from beneath the slab does pose a problem, but it’s not related to the carpet.
CRI: Where does basement moisture come from?
LM: Sources of moisture that would perpetuate the growth of mold or mildew in a residential basement include: leaks, “sweating” or condensation off cement block or poured walls, over-wetting from cleaning by an uninitiated operator or do-it-yourselfer, an unbalanced humidifier or HVAC system, or moisture in the substrate. The most likely sources of moisture coming up from the floor are either moisture in the concrete slab itself or moisture vapor emissions coming up from beneath the slab.
CRI: Water in the concrete?
LM: Moisture in a concrete slab comes from two sources: water of convenience, which is the term for the water necessary to mix the cement to a workable consistency, or free water, which is essentially water that doesn’t combine with the dry cement, but instead roams free inside the slab and constantly tries to escape. Water vapor that comes up from beneath a concrete slab usually comes from failing to install a low-permeance vapor retarder directly below the slab. Not using a barrier to stop the moisture sets the stage for problems.
CRI: Why so many problems keeping basements dry?
LM: Moisture-related flooring problems are common today for a number of reasons. One of the biggest causes is rushing the job – concrete isn’t given sufficient time to dry to an acceptable level for installing floor covering. Often, the vapor barrier beneath the slab is missing, inadequate, or positioned incorrectly. Moisture protection should be placed directly below the concrete, and it should be from10 to 15 mil thick so it won’t tear. One good product is Stego Wrap vapor barrier, but there are several others available. Anything less can be compromised too easily.
CRI: Anything else to consider?
LM: A properly working and balanced HVAC and air filtration system, plus an owner knowledgeable in their efficient operation are of prime importance in preventing conditions that propagate the growth of mold and mildew in the living space. Maintaining carpet by vacuuming frequently with a high-efficiency vacuum that may also have a HEPA filter will keep carpet free of dust and dirt and free of substances that can infiltrate carpet and become food sources for mold and mildew. Cleanliness of all surfaces, not just carpet, is key to preventing mold and mildew growth in any space.
CRI: Would you say that carpet is environmentally friendly?
LM: Sure. Carpet is recyclable - nylon carpet can be recycled into new carpet or other plastic products such as automobile parts. PET polyester carpet is made from recycled water and beverage bottles. The carpet industry is one of, if not the most conscientious industry relative to recycling and waste control. Work is continually being done to find more uses for recycled carpet and to keep it out of landfills.
CRI: Okay, Lew, I’m sold. Synthetic carpet is a good choice in a basement.
LM: There is no reason for carpet not to be used below grade, or above grade, in residential or commercial applications. In fact, with the right cushion, carpet is actually the best flooring material to use as it adds comfort to the space, provides thermal insulation, and helps thwart sound and noise. Carpet is also safer for young children to play on, as a fall on carpet is much less threatening than a fall on hard surface flooring. Carpet breathes, which means that small amounts of moisture vapor under the carpet will have a chance to dissipate into the air, instead of being trapped under a non-permeable material like sheet vinyl flooring, for example. Simply put, there is no logical, rational, reasonable, or viable reason not to use carpet in a reasonably dry basement area.
Thanks, Lew – I’d say that about covers it.