Healthy Indoors Magazine
Issue link: https://hi.iaq.net/i/971754
Healthy Indoors | 27 After showering or bathing, operate the exhaust fan in the bathroom. In addition, leave the door open and operate an oscillating fan in the bathroom to help dry surfaces. If you have a central humidification system, keep the RH in habitable rooms under 40% (lower in extreme cold). The same holds true if you use a portable humidifier in any particular room. Always measure the RH with a thermo-hy- grometer. If you see moisture condensing on windows, you need to exercise more control over potential moisture sources in your home. Keep your exterior closet warm. A closet with one or more walls facing the exterior can develop conditions of el- evated RH. This can lead to mold growth on those walls, as well as on goods stored on the cool closet floor. It's best not to overstuff such a closet with personal goods; keep goods up off the floor and away from cool walls. Don't have rugs or carpeting on the closet floor, as car- peting captures biodegradable dust. Remove the dust from the floor and baseboard trim. To warm the air and help control the RH in an exterior closet, you can heat the closet with a heater specially made for the purpose (or just the light), or you can keep the door open to increase the flow of warm air into the space. You can also install a louvered rather than solid closet door. Be careful not to place any combustible materials near an exposed, incandescent closet lightbulb. Don't keep some rooms cold while you heat other rooms. In the winter, it's tempting to heat only the rooms that you use and leave other rooms cool. In homes with wood-burning stoves, I've often found that some rooms near the stove are toasty, while others are uncomfortably cold. This may save on the heat bills, but unfortunately, el- evated RH conditions can develop in the rooms that aren't adequately heated, even if they are above grade. And then you know what may happen next…mold growth. Isolate your crawl space. Unlike the Building-Code re- quirement, a crawl space should be isolated from the ex- terior and dehumidified; otherwise, humid air can enter the space and lead to condensation and mold growth on cool surfaces. And if a crawl space has a dirt floor, the dirt should be covered with a mesh-reinforced vapor barrier or even with appropriate cementitious material, to limit the evaporation of moisture from the soil. Mold growth on joists and subfloor in unfinished basement due to elevated RH, and not to leaks. May Indoor Air Investigations LLC Aspergillus mold growth on a basement beam due to ele- vated RH, and not to leaks May Indoor Air Investigations LLC If you have an indirect-fired, hot-water system or tank- less system (i.e. the boiler heats the domestic hot water), this will help control the RH, because the boiler operates year-round and produces heat as it does so. Don't over-humidify above grade: In the winter, we don't open windows and doors that much, so moisture can build up in a house in above-grade rooms. If you have an exhaust fan over your cook stove that vents to the exterior, use the fan whenever you cook or bake, and try to cook and bake at the same time.