I have recently presented a number of discussions about mold, including the causes and the remedies. Many have appreciated the science and we have been fortunate to have helped many folks with their mold challenges. People understand that when you either eliminate the food or water, you can also eliminate the potential for further mold growth.
The devastation at the Jersey shore and New York’s Staten Island and Queens, however, has taken the practical application of mold science to a new level. Tens of thousands of homes were inundated with Category 3 sea water, in some cases four to six feet. Most homes were not destroyed but suffered extensive water damage. The lucky homeowners were flooded only in their crawlspaces and were able to avoid demolition of building finishes in the living space. Many others had a foot or two of water in the living space and face extensive demolition.
The question I have been answering for the last two months is “How do I avoid mold growth from all of this water damage?” The good news (probably the only good news) is that mold growth is not an immediate concern in this disaster for one simple reason: the storm occurred at the end of October when we have generally cold fall and winter temperatures in the northeast.
The cold temperatures have given us some breathing room, since mold does not enjoy temperatures in the 30’s and 40’s. The weather has given us time to consider our options and make the right decisions. The folks in New Orleans did not have this luxury when Katrina struck on August 29, 2005. Temperatures were over 100 Degrees F. every day and mold growth just exploded. So we are at least fortunate in that regard.
Warmer weather is coming, of course, and mold will absolutely grow if the building conditions have not been properly managed. So how do you avoid mold growth in the wake of Sandy? The process is relatively simple and involves three main steps: dry, clean and treat.
Drying after Sandy:
Drying is straight forward as long as you consider several potential stumbling blocks. Since we are in winter, the cold weather will affect how you dry. Standard dehumidifiers are rated for operation at 80 Degrees F., and their efficiency decreases markedly at lower temperatures. Below 50 Degrees F., their efficiency drops to near nothing. So unless you have heat in the building, you are wasting your time with dehumidifiers in cold weather.
And of course if you have heat, you do not need dehumidification. Heating provides natural dehumidification, as I have explained in previous discussions. We have had great success with propane forced air heaters, which can get the temps up to 90 Degrees F. to expedite drying. Just make sure to crack open the windows to allow the moisture (and carbon monoxide) to escape.
Wall and floor cavities must be opened. There is no way you can dry a wall cavity, especially one that is insulated, from outside. That means cutting drywall a foot or two above the flood line and removing all affected insulation that holds moisture like a sponge. Most folks have understood this, as evidenced by the massive piles of demolition debris that appeared on curbs from Queens to Wildwood. Taking out the wet drywall and insulation is just common sense.
More troubling is the issue with floor finishes. Carpet is recognized as a sponge and so it goes away. Hardwood flooring will start to cup and also usually goes away. People have the most trouble with ceramic and vinyl tile, since the tiles themselves are not usually damaged by water. But what about the floor beneath? Keep in mind we are talking about drying and it can be very difficult to dry plywood under tile, since the tile acts as a vapor barrier. This is even more of a problem when there is more than one layer of plywood, such as the luan that is under many tile floors. The rule for floors is to get down to one layer of floor, usually the subfloor. If this layer is structurally intact it can be dried, cleaned and salvaged. The floor finishes, however, including the ceramic and vinyl tile, usually need to go if they got saturated with water.
The exceptions are vinyl and ceramic tile on a concrete floor slab. As long as the flooring is comprised of inert materials that do not provide food to the microbial critters, it can stay. You just have to get it dry and clean, and you are good to go.
The tiled walls of bathrooms and kitchens present a similar dilemma. Most folks prefer to salvage the bathroom, again because the tile itself is unaffected by the moisture. But it also acts as a vapor barrier and retards the drying of the underlying drywall. Drying tiled bathroom walls is a long and arduous process but it has to get dry. Remember, the drywall is the mold food that we are trying to salvage. We can avoid mold only by controlling the moisture. It has to get dry.
By the way, for those forward thinking folks that constructed their bathroom walls with cement board instead of drywall, the issue of drying is essentially a non-issue. The cement board does not readily absorb moisture and is also not food to the microbial critters. You are definitely ahead of the game with the cement board products.
Cleaning:
There seems to be a lack of understanding on the part of some restoration contractors regarding the meaning of cleaning. For most of us, it is what our parents made us do as children, “and use a little elbow grease while you’re at it.” For those of you who did not get the memo, allow me to quote from the seminal industry publication Bioaerosols: Assessment and Control, published by the American Conference of Governmental Industrial Hygienists (ACGIH) in 1999:
“Cleaning is the process of removing all foreign material (e.g. soil, fungal growth or other organic matter) from hard surfaces.” Duh.
We clean so that the dirt and debris that can become mold food is removed. We also clean so that any disinfectant product we may decide to use is more effective. As stated in the Standard and Reference Guide for Professional Water Damage Restoration, published by the Institute of Inspection, Cleaning and Restoration Certification (IICRC) in 2004, “An important limitation of using biocides is that they are deactivated by organic contaminants in water or on surfaces”.
So the key point is to get it clean. This means wiping or mopping with a good detergent cleaner, or cleaning with a shop vacuum equipped with high efficiency particulate air (HEPA) filters. These filters are available at Home Depot for the Rigid brand shop vacuum. They work very well and we use them in our own business.
Treatment:
The indiscriminate use of disinfectants (biocides) in lieu of cleaning is not recommended by any standard setting agency. In fact, the standards are unanimous in warning against the uncontrolled use of biocides. To quote IICRC again, “In Category 3 and Category 2 water damage situations, the preferred remediation procedures rely more on thorough cleaning and source removal, rather than application of strong, potentially hazardous biocides.”
The reasons for the biocide warnings are several. Biocides are registered pesticides because of their potential human hazard. After all, they are designed to kill organisms. In addition, their use on organic materials such as wood and paper is ineffective, since the chemical reacts with the organic material and all you are left with is water, which generally comprises more than 99% of the product. As stated by ACGIH, “application of water-based biocides introduces additional moisture into the building environment, which may not be desirable.” The situation is summed up by the NYC Department of Health in their 2008 Assessment and Remediation of Fungi in Indoor Environments: “The use of gaseous, vapor-phase or aerosolized (e.g. fogging) biocides for remedial purposes is not recommended.”
So where does that leave us with antimicrobial treatment? Over the years we have come to favor the use of antimicrobial encapsulants (paint) in areas that are subject to moisture. While encapsulation may not be necessary in areas of the home that are not exposed to moisture, in a marine environment like the shore just about everything is exposed to moisture. This is particularly true after the Sandy devastation, when flood waters inundated crawlspaces and living spaces. We have found that a good encapsulating paint has several significant benefits:
1. After wood has been flooded with water, the grain and pore spaces swell open. Painters know this and frequently use water to open the grain of wood prior to applying their primer, to improve the adherence of the paint. But for our purposes, the pore spaces provide micro-niches that mold and bacteria love. The encapsulant fills in these pores and makes the surface more inhospitable to future microbial activity.
2. High quality antimicrobial paints have been on the market for years and have a solid track record. I have seen several situations where a water loss was remediated with cleaning and encapsulation, and when a repeat water loss occurred years later, the encapsulated wood did not care. I have never seen mold grow on a good quality antimicrobial paint.
3. Encapsulation is essentially what we do with our homes when we keep them painted. The paint resists weathering and prolongs the life of the painted component. The situation is similar in crawlspace that is open to the marine environment. The encapsulated beams and floor deck are going to hold up better to the weather than bare wood.
I have found that while encapsulation does add cost to the remediation project, it is well worth it. The level of future odor, microbial activity, and moisture damage will be significantly reduced.
To summarize, the remediation process needed to avoid future mold growth is dry, clean and treat. Spring time is coming and temperatures will soon favor mold activity. The sooner you get the building open and dry, the better your chances of avoiding mold growth.