Q. We are rehabilitating an older house that had a leaky roof, which caused extensive mold problems inside the house. We have already cleaned up a lot of the mold, using a cleaner from a home center, but are looking for more information and tips. Can you help?
A. Homeowners can clean up small areas of mold, but extensive mold damage should be handled by a mold-remedial expert.
Small areas – those that can be treated by do-it-yourselfers – are generally defined as covering no more than about 10 square feet. If a professional is needed, look for names under Fire and Water Damage in the yellow pages.
Mold often appears as a black or gray coating on surfaces that have been exposed to water for some reason, such as floors or ceilings under roof leaks, walls that contain trapped water, areas around plumbing leaks, seeping basement walls, and the like.
It is usually recommended that interior mold cleaning be done by scrubbing with a solution of household detergent, not with chlorine bleach. If bleach is necessary, dilute 1/4 cup with a quart of water.
An effective dust or respirator mask should be worn, along with gloves, goggles and other protective clothing. Rooms being treated should be sealed off from other parts of the building while work progresses. Kits sold for mold testing are not recommended.
There is a great deal of information on dealing with mold on the Internet. One excellent source is the site of the Washington State Department of Health, www.doh.wa.gov (enter Got Mold in the search space).
There is also useful information at www.epa.gov/mold, the site of the Environmental Protection Agency.
Q. We have a damp basement that has a musty odor. We use a dehumidifier regularly to remove moisture. Is it a good idea to open basement windows for ventilation?
A. I think it is a fine idea to ventilate basements by opening windows on fair days when the outdoor humidity is low – not more than 40 or 45 percent relative humidity.
The dehumidifier should be turned off when ventilating, of course. If possible, set up a fan at one of the windows to exhaust damp, stale air and pull in fresh air.
I don’t recommend ventilating when the outdoor relative humidity is high; it will add more moisture to the damp air and possibly increase the chances of condensation and foster formation of mold.
Q. My central air-conditioning unit is quite old and I am considering getting a new one to take advantage of tax credits. I use oil for heating and my oil bills are moderate. I live in a cold-climate area and don’t use the air conditioner much. A contractor recommended installing a heat pump. I understand these don’t work well in cold weather. Do you think the heat pump is a good idea?
A. Heat pumps, which provide both heat and air conditioning, are popular in warm climates, where they are quite efficient and cost-effective.
However, typical air-to-air heat pumps, which draw heat from outside air in winter to provide heat inside the building, aren’t very effective in cold temperatures, causing expensive all-electric backup heat to kick in. It is possible to substitute oil or gas heat for backup in some pumps.
I have talked to a number of heat-pump owners in cold-climate areas, and some who own conventional air-to-air pumps are very unhappy with the winter performance. Some newer air-to-air models of pumps are more effective in lower temperatures, and pumps that draw heat from the ground or underground water are also more efficient (and more expensive to install) than typical air-to-air models.
If you are interested in a heat pump, ask the contractor for names of others in your area who use them. Check on the performance. If the reports aren’t positive, and judging from the information you supplied, I would keep the existing heating system and consider updating the air-conditioning unit only.
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