BREAKING MOLD'S HOLD ON YOUR HOUSE

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BREAKING MOLD'S HOLD ON YOUR HOUSE

Saturday, October 29, 2005

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Drying -- as rapidly as possible -- is key to mold remediation. To

control mold, surface humidity should be less than 70 percent,

relative humidity should be between 40 percent and 60 percent and

moisture in the wood should be less than 20 percent. Confused? Here

are the steps to reach that goal.

Dress the part. For removing moldy belongings, wear boots, gloves

and a neoprene respirator rated N95 or higher. For removing drywall

and the like, wear a full-face air-purifying respirator and

disposable coveralls.

Isolate the area. Hang plastic sheets in doorways to separate

unaffected areas, such as upper floors or back rooms. Cover air

vents.

If it's porous, it has to go. That includes Sheetrock, ceiling

tiles, upholstery, carpet, vinyl flooring and insulation. Semiporous

products, such as some woods, might be saved, although anything

built in layers (like a floor) can harbor mold or bacteria between

the layers and should be removed. Plaster doesn't usually harbor

mold, but if there's insulation behind it, both have to go. Remember

that there's probably twice as much mold on the back of the

Sheetrock than what you see on the surface due to the absorption of

water into the wall to a level higher than floodwater reached. Solid-

core doors can sometimes be saved and restained, although hollow

doors, baseboards and door frames should be removed.

The process. In homes that were flooded with shallow water, where

mold is confined to the lower part of walls, remove the Sheetrock

with a horizontal cut several feet above the mold. A good rule of

thumb is to cut at 4 feet, since Sheetrock is sold in 4-foot widths

and can slide into the hole without having to be trimmed.

Total gutting of Sheetrocked walls and ceilings will be necessary in

more heavily damaged homes. Wood laths behind plaster must be

removed if they were submerged and display visible mold.

Before removing drywall, spray moldy areas with water to reduce dust

release. Or, before cutting into the drywall, tape a sheet of

plastic over it so that spores are not dislodged. Experts recommend

bagging discarded drywall.

Scrub or wire-brush discolored wood studs with disinfectant. Once

dry, affected joists can be encapsulated with a fungicidal paint

to " glue " any remaining mold in place and keep it from growing.

Clean and disinfect. Surface mold on non-porous materials, such as

glass, metal, concrete, hardwood or plastic, can be cleaned with a

nonphosphate cleaner (read ingredient lable to see if product

contains phosphates). Follow with a disinfectant containing bleach,

alcohol, hydrogen pyroxide or phenolics. The Terrebonne Readiness

and Assistance Commission recommends a combination, mixed in a

garden sprayer, of ¾-gallon of bleach; ¼-gallon of trisodium

phosphate, or TSP, a common ingredient used in pressure-washing that

is available in paint and hardware stores; and 1½ gallons of water.

Cleaning must remove, not just kill, mold, since dead spores pose as

much of a health risk as live ones.

Vacuum surfaces. Use a vacuum with a sealed High Efficiency

Particulate Air, or HEPA, filter, which is at least 99.97 percent

efficient at removing all particles in the air 0.3 microns (half the

size of a dust particle) or larger.

Dry it. Then dry it some more. Don't be in a hurry to cover up those

gutted walls. Fans, air conditioning and dehumidifiers can help dry

the air, but it takes a long time. The relative humidity of the home

(the amount of moisture in the air relative to the maximum amount it

can hold) should be between 40 percent and 60 percent for efficient

drying. You can invest in a hygrometer ($10 to $60) to measure it.

Dead mold doesn't return, but new mold can sprout in as little as

three days if things stay damp.

Test it. Before you rebuild, use a moisture meter (available at

hardware stores starting at about $100) to make sure studs and

joists contain less than 20 percent moisture. And since cleanup can

release lead paint dust or asbestos, you might want to test older

homes for those substances before reoccupying.