Keep indoor humidity below 60 percent relative humidity and ideally between 30 and 50 percent, dry anything that gets wet within 24 to 48 hours, and fix the water source rather than the stain. Those three sentences are the EPA guidance and they are the whole of prevention. Everything below is where in a house those three get tested.
Mold can grow on virtually any organic material as long as moisture and oxygen are present, so the food and the air are already in the building. Moisture is the only variable a homeowner controls, which is why a prevention list that talks about anything else is talking about the wrong thing.
Buy a hygrometer first
It is the cheapest instrument in this trade and the only one that turns a hunch into a number. Put one in the basement and one in the room that worries you, read them morning and evening for a week, and write the numbers down. A basement here that reads above 60 percent through August has told you what to do before anybody visits.
If the readings sit high, a dehumidifier sized for the space, running through the humid months and draining to a pump or a drain instead of a bucket somebody has to empty, is the single most effective prevention purchase in a house like this.
The basement, which is where it starts here
- Get stored contents off the floor and away from exterior walls so air can reach the surfaces.
- Lift rugs off a cool slab in summer, because the underside stays damp long after the top feels dry.
- Check for efflorescence, the white powdery deposit on masonry. It is salt left as water moves through the wall and evaporates, and it means water is passing through the material.
- Test the sump pump by lifting the float before the wet season, and find out whether it has a battery backup.
- Insulate cold water pipes and any uninsulated duct that sweats in summer, because condensation on a cold surface is a moisture source with no leak behind it.
Along the Passaic River corridor in Passaic County, and in the border towns of Essex County and Bergen County, basements take water in heavy rain, so the outside list below matters as much as anything done indoors.
Outside, because most basement water starts there
- Clear the gutters twice a year, and more often under trees.
- Extend downspouts so they discharge away from the foundation and not beside it. This is the cheapest useful fix available.
- Check the grading so the ground falls away from the house for the first several feet, and look for beds that have been topped up until they slope back.
- Look at the flashing at every roof penetration, including where a chimney passes through, because a failed joint appears inside as a ceiling stain feet away.
- Clear window wells, which fill in heavy rain and push water at a basement window that was never meant to hold it.
Bathrooms, kitchens and laundry
- Run the bathroom exhaust fan during the shower and for twenty minutes after it, and check that it vents outside and not into the attic.
- Keep grout and sealant closed at the base of a shower and around a bath, because that joint is where water gets behind the surface and into framing.
- Look under sinks with a flashlight twice a year, feeling the joints with a dry hand and looking for a white crust or a green stain.
- Check the washing machine hoses for bulging and rust at the crimp, and look at the wall behind the machine.
- Make sure the dryer vents outside and that the duct is clear, because a blocked run puts warm moist air into the room.
The heating and cooling system
Change the filter on the schedule the equipment asks for, keep the condensate line clear so it does not back up into a ceiling or a closet, and have the coil looked at if there is any smell when the system runs. A system that draws from or passes near damp material moves that air into every room it serves, so an HVAC problem presents as a whole house problem.
After anything gets wet
- Stop the water and photograph everything before it moves.
- Get standing water off the floor the same day.
- Dry the material, not the room, which means moving air across the wet surface and taking the moisture out of the air instead of pushing it somewhere cooler.
- Check what is under and behind: the pad, the subfloor, the base of the wall, the back of the cabinet.
- If the material is still damp after two days, or if it smells, treat it as a job for meters.
What not to do
The EPA does not recommend a chemical or biocide that kills organisms, chlorine bleach for example, as a routine practice during mold cleanup, and it warns never to mix a chlorine bleach solution with cleaners containing ammonia because toxic fumes can be produced. Painting over a stain, spraying a fragrance and closing a door on a damp room are the other three habits worth dropping.
The EPA also gives the line for what you can handle: an area less than about 10 square feet, roughly a 3 foot by 3 foot patch, in most cases. Above that, or where the water was sewage or floodwater, or where the growth is in or near the heating and cooling system, it is contractor work.
The seasonal version
Spring is for the outside list and the sump pump. Summer is for humidity readings and the dehumidifier. Fall is for gutters and flashing before the wet months. Winter is for frozen pipe prevention, which is the same list from the other end: insulate exposed runs, drain the outdoor spigots and keep heat in rooms nobody uses.
If prevention has already been overtaken by events, the inspection is the next step and it is set out in What happens during a mold inspection in New Jersey. The remediation method is on Mold Remediation and the drying side is on Water Damage Restoration, with a free written estimate before any work begins.
This article is about Mold Remediation.