Mold Issues in Perspective
Got an e-mail today. Lots of questions about mold issues as they relate to structural drying. Happens almost daily these days. Where are we going? Who's leading the charge? Why that direction? Does anyone know what's what?
Simple questions, complicated answers.
Let me start by saying that insurance companies, in general, are in a state of chaos over these issues because they are talking to a lot of the wrong people. Some 65 percent of insurance claims dollars are spent on floor coverings. Proper drying procedures can result in 40 percent of those dollars being saved. Our book, Flood Damage Restoration - Part I, covers the pricing and procedures issues quite well.
Sooner or later insurance companies need to stop listening to people who keep saying, "We've never done it that way before."
The Institute of Inspection, Cleaning and Restoration Certification (IICRC) is trying to be two years ahead of the industry, to anticipate where we're going, and to project our future training and certification needs. Dedicated volunteers on IICRC committees are meeting regularly - sometimes 15-17 hours in a day - to debate issues pertaining to structural drying, psychrometry, mold, etc. Then they go back into laboratories to prove or disprove the theories they discussed before the next meeting. Insurance companies need the input of this international, independent, non-profit certification body.
End of sermon. Now to the facts:
There are four principles of drying:
* Remove the excess water
* Promote evaporation
* Increase dehumidification
* Control temperature
With these principles in mind, you can dry anything quickly and efficiently, with guaranteed documentation as to the result. Let's talk a little more about each:
Excess water removal
Since carpet and cushion are the primary flooring materials used in the US and Canada, I'll focus on that. But remember, we have 18 categories of certification involving inspecting, cleaning and restoring many different construction materials. Assuming a clean water source and timely conveyance of the Notice of Loss, there are three ways to remove excess water: Absorb standing water on furnishings and floorings, pump it out of below-grade construction areas, and - primarily - extract it with wet vacuum equipment. Extracting water with a light wand removes about 7 percent of it from carpet and cushion. A drag tool moves us to around 18 percent. Today's specialized extraction equipment allows us to remove some 77-88 percent of flood water, thus reducing drying time up to three days.
By far, this is the most violated principle of drying, and there is no excuse for it. Insurance companies must stop listening to those who say, "We've never done it that way before," or, "We tried that and it didn't work." The translation is, "We aren't willing to make the investment in equipment or training for our people." They know that insurance companies also are reluctant to change and besides, contractors are making a ton of money charging for unnecessary services. Of course, when new ideas are introduced, those contractors throw up the old "mold smoke screen."
Do the job right from the outset and mold simply isn't a problem. Careful extraction of carpet and pad should cost around 40-50 cents per square foot.
Changing liquid into vapor is what evaporation is all about. We use high velocity airmovers to accomplish this, at a general cost of about $25 per day. The rule of thumb for airmover quantities is one per 10-14 linear feet of wall space. Airmovers are placed at a 45-degree angle to the wall and touching the baseboard, with the venturi, or inlet, side toward the room.
Using this quantity of air moving equipment does several things. First, it dries baseboards and walls with wicked moisture in them. Second, it speeds the drying of carpet and pad in the 10-foot + area immediately in front of the airmover. Repositioning airmovers every 24 hours on the monitoring trip ensures rapid overall drying, even when plywood or OSB subfloors are present. We hardly ever have to remove, replace or repaint baseboards anymore. Although there are situations that mandate cushion removal, we're saving about 60 percent of the cushion these days because of increased knowledge and much-improved, high-capacity equipment. Everything has changed in the last year or two.
Moreover, air movement and evaporation have a lot to do with mold growth, or lack thereof.
Let me add that as carpet or other materials dry, fine soil particles (dust, mold particles, allergens) wick to the tips of yarns where they are rendered airborne by all the airmovers we've set up. At that point, asthmatic or sensitive occupants begin to experience allergic reactions that are totally unrelated to water loss or mold growth. It's simply a reaction to its own household soil, which had been trapped harmlessly in the carpet pile. This is why air scrubbers with pleated pre-filters and HEPA final filters may be needed inside buildings to contain this problem, not diverting attention to a non-existent "mold problem."
The insurance industry's lack of knowledge on IEQ issues in this area is alarming and costly to itself and its policyholders. Again, insurance companies are talking to the wrong people.
Once moisture evaporates into air, relative humidity (percent) and specific humidity (weight) go up. But so does vapor pressure, which is the force exerted by gasses on its surrounding environment. It is vapor pressure that moves moisture into - even through - solid materials, equalizing its moisture content with that of the surrounding air.
So how many and what type dehumidifiers are needed? Good question. But to answer it, we must know the extent, or "Class," of water damage. According to IICRC, there are four "Classes" of water damage (not "Category").
Classes of Water Damage
* Class 1: Slow Rate of Evaporation. Water losses that affect only part of a room or area; or losses with low-permeance/porosity materials (e.g., plywood, particle board, structural wood, VCT, concrete). Little or no wet carpet and/or cushion is present. Minimum moisture is absorbed by materials, which release that moisture slowly.
* Class 2: Fast Rate of Evaporation. Water losses that affect the entire room of carpet and cushion. Water has wicked up walls less than 24 inches. There is moisture remaining in structural materials (e.g., plywood, particle board, structural wood, VCT, concrete).
* Class 3: Fastest Rate of Evaporation. Water may have come from overhead. Ceilings, walls, insulation, carpet, cushion and subfloor in virtually the entire area are saturated.
* Class 4: Specialty Drying Situations. These losses involve wet materials with very low permeance/porosity (e.g., hardwoods, subfloor, plaster, brick, concrete, stone, crawlspaces). Typically, there are deep pockets of saturation that normally require very low specific humidity.
Determining Dehumidifier Requirements
Calculate the cubic footage of the room or area to be dried. Example: 30' x 50' = 1500 sf x 8' = 12,000 cf. Initially, effective drying of structural materials requires that air in a structure must be exchanged based on the dehumidifier's ability to remove a specific number of pints per day. On-going equipment use is based on psychrometric calculations to verify adequate and safe drying.
Today, we have three types of dehumidifiers: Conventional refrigerants, low grain refrigerants (LGR) and desiccants. LGR dehumidifiers are in a separate category because test results indicate they are about 20 percent more effective than conventional refrigerants, especially in the latter stages of drying and where less porous materials are involved.
OK. To figure the number of pints of moisture we need to remove from a structure, we divide by a number from the table above based on the Class of water damage and the type of dehumidifier we have available for use, or, in the case of desiccant dehumidifiers, calculate the number of air changes per hour (ACH) required for efficient drying.
Example: 1500 sf Class 2 water loss @ 12,000 cf ? 50 = 240 pints at AHAM
Drying capacity, based on both equipment manufacturer and AHAM ratings.
**Manufacturer published specifications
> **Association of Home Appliance Manufacturers
Alright, to achieve the 240 pints of dehumidification capacity needed to adequately dry this structure, I'll need, for example, two Phoenix 200s (124 pints at AHAM each) or two Drizair 2400s (148 pints at AHAM each). Obviously, power requirements and circuitry within the structure must be considered as well.
Further, the charge for those dehumidifiers should be around 50-60?per manufacturer-rated pint of dehumidifier capacity per day. Why manufacturer-rated capacity rather than AHAM? The manufacturer rating usually is written on the front of the dehumidifier for everyone to see.
Controlling temperature throughout the job is critical for promoting rapid evaporation (warm air holds more moisture than cold air), for promoting efficient dehumidification, and for controlling mold growth (at least to some extent).
OK. Admittedly this probably is more answer than you had question. We have an "Advanced Water Damage Restoration" Seminar at our Dothan training facility, in which we actually flood and dry two rooms of carpet and pad to illustrate all this stuff I've referenced above. Our book, Flood Damage Restoration - Part 1, Organizing, Management and Marketing, has an entire chapter devoted to pricing: Price lists, price justification and how to price multiple jobs in major flooding situations.
Further, IICRC now has a new certification category in which approved schools flood an entire house, complete with plywood subflooring, drywall and insulation. Then, approved instructors demonstrate in-place drying techniques over the course of three or four days. We look forward to seeing you at these courses in the future.