Home & Garden Columns

About the House: The Stinky House Syndrome

By Matt Cantor
Friday December 29, 2006

Mr. & Mrs. American home owner, are you suffering from Stinky House Syndrome? Does your house smell bad? Do strangers flee your dwelling soon after entering? Do relatives plan family gatherings at the homes of less scintillating family members? Are you engaging in microbial experiments without possession of the pertinent advanced degree? If you answered yes to any of the above, you may be a candidate for dehumidifier ownership. 

Once again, it’s the rainy season and the calls about stinky basements, green growths on baseboards and sneezing basement dwellers are pouring in (so to speak). As property values and rents grow, more and more people find themselves living in or using basements or backyard sheds that do not provide adequate protection against damp conditions. Even if you only have a damp basement below your living space, you can be subject to elevated humidity levels that can make your home feel clammy and cold. This is a complex area of home care and much needs to be said that I can’t cover in 1,000 words or less. But there is a formidable tool in the war on mold that is worthy of a some discussion, and that’s our friend the dehumidifier. 

A dehumidifier is essentially an air conditioner but with a few notable differences. The technology that’s used to chill air in your refrigerator or air conditioner chills a set of coils and then pumps the waste heat to another set of coils for discharge. In the case of an A/C those are on the outside. And if you put your hand over them, you can feel the heat. The cold coils also gather moisture in the air since moisture tends to condense on a cold surface, just as it does on your windows when you have the heat turned on. 

A dehumidifier condenses moisture in the atmosphere on those cold coils and allows it to drip into a pan. Rather than moving the warm coils to the outside, they are placed just past the chilling and dripping business in the system and warm the air back up before releasing it into the room. This way, you are able to remove the moisture without cooling the room. Of course, if you want it cool and dry, you can simply run an air conditioner, although they are somewhat less efficient at removing moisture since they are not designed to provide this as their sole function. 

Now, what to do with all that water? First, keep in mind that the water gathered from a cold system like this isn’t safe to drink, since it is likely to contain fungal matter and dust. So it’s best to simply discharge it down a drain or out to the garden. Small inexpensive dehumidifiers fill a small trough or tray which must be taken out and emptied from time to time, but larger ones are provided with drain pipes and can be set up to run with almost no maintenance for very long periods. These larger models (actually all of them) are rated in terms of “pints per day,” and it’s best to try to choose one using this system. Small models are less than 10 PPD and large ones can be over 40 PPD. The larger ones should be expected to cost well over $1,000 but may well be worth it if you’re experiencing real distress. 

Every year I meet a few people who have a bad situation that calls for a dehumidifier. One couple that I met last year had a tenant living in a basement apartment. Part of the tenant’s space was getting wet from leaks and featured a lovely zoological menagerie of fungi and protists (part of the mildew family). Everybody gets freaked when this is happening and all sorts of allegations of devil worship and bad genetics get hurled about but the simple truth is that people are dealing with this all the time. It’s not a basis for bad behavior or threats. It’s just nature doing what it always does when some basic requirements are met. It grows stuff. Fungi love moisture.  

They also need oxygen and food but that’s available at everybody’s house. I haven’t seen any houses that don’t have a nice source of sugar and oxygen. A damp 2 x 4 will work nicely, thank you very much but a sheet of paper surfaced sheet rock will work even better. We line the inside of our houses with paper and it’s no shock when stuff starts growing on the surface. We really ought to quit this odd habit and it is happening slowly. Alternatives to paper surface gypsum drywall have been around for some time and, in these litigious times, they’re really surging. I suspect that we won’t be able to find the paper type in another 10 years but I digress. 

So we have food, air and only need water. How much water do we need to grow fungi (that includes the molds and most mildew). The answer varies with the organism but it’s about 70 percent to 100 percent. Few of these things grow below 60 percent and 50 percent is quite safe and comfy.  

Basements often have walls that are damp and the moisture levels easily meet the requirement. When moisture is present on the surfaces it evaporates and becomes part of the atmosphere. If there is enough of this, the entire house can achieve levels where fungi begin to grow. While rare, it is not unusual to have portions of basement, window sills, closets and spots on ceilings where little farms are agrowin’. 

Although it may seem almost too easy to find plausible, the simple deprivation of an adequate level of moisture is all that is needed to prevent fungi from growing. They just stop growing when things dry out. True, the dead spores remain and can affect the immune systems of some fairly allergic persons but for the most part, when things dry out, the ill effects vanish. It is wise to clean the surfaces and possibly replaced damaged or deeply infested materials such as sheetrock if these have become filled or covered with culture (of course, doesn’t all the Bay Area have that problem?) but once the level of required dampness is gone, there just won’t be more growth. If you want to clean and kill mold spores, a dilution of bleach works nicely. 

There are many things that one can do to prevent this including creating proper drainage, venting the spaces below the house, the use of plastic barriers and sealants but for situations that are currently unmanageable, a dehumidifier is a quick, simple and relatively inexpensive fix. Downside?, they use electricity. If you’re thinking of getting one, especially a “whole crawlspace” or “whole house” model, check out the energystar.gov website. You can get a rebate for making the right choice and help to control your electric bill. Like their cousins, the air conditioners, dehumidifiers use a fair amount of electricity but given the important job they do, it’s worth it. I would make sure I bought enough but not too much capacity so as to control the energy cost. Better models have humidistatic controls that allow you to set the percentage of moisture you like. Don’t set them too low. It’s not comfortable and will only cost you more money. 

After the rainy season, you may want to take some other actions in response to mold and wetness but in the immediate, the use of a dehumidifier can be a lifesaver. It may save your hacking lungs, the frame of your lovely old Victorian or the precious relationship you have with the nice young man who lives down in the basement. 



Got a question about home repairs and inspections? Send them to Matt Cantor at mgcantor@pacbell.net.