How Do I Control Humidity In My House?

by Erik North on November 5, 2011

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I get a few funny looks during audits when the conversation turns from insulation to water and moisture control. But the two are interconnected whether or not it is obvious.

Your entire house is made of wood, paper, concrete and plastic. Every one of those materials either holds loads of moisture or stops it.

The good news about your house: two of those materials will never have mold issues. The bad news is that the other two can. Over long periods in high humidity situations, mold can become an issue. Because of this we need to be conscious of how to control humidity in your house.

Dehumidifiers – Just Say No (At First)

The first place most thoughts go when discussing humidity control is dehumidifiers. Kinda makes sense, it’s right there in the name. And dehumidifiers do a bang up job of condensing humidity from the air. Sometimes they’re absolutely necessary for moisture control. However dehumidifiers draw an absolutely huge amount of electricity and there are loads of other things you can do before resorting to them.

I’ve had one particularly data conscious customer who figured out that their dehumidifier increased their electric bill by 70% while running. Yech. They’re so expensive to run, it makes sense to do other household projects before defaulting to the dehumidifier.

How to Control Humidity – Avoid Some Bad Habits

First, a few improvements in habits can help. Maine is known for fantastic lobster and beautiful foliage. Our whole tourist industry is based on the idea that you (the rest of the country) should come here and view the colorful foliage and eat a lobster roll. Well, Maine has gobs of foliage and so has gobs of trees some of which get cut down for firewood.

Wood as a heat source is regaining some of its popularity as a green, local alternative to importing OPEC oil at $100 a barrel. An increasingly common sight is green wood drying indoors. This is bad. From an interior moisture stand point, real real bad. A cord of green wood will dry out thousands (yes, thousands) of pounds of water while seasoning. A gallon of water weighs a bit over 8 pounds. Imagine dumping 200 gallons of water on your basement floor.

Another household habit that’s gaining green traction is drying laundry outdoors. However, those same folks move the drying indoors once the weather turns cold. In a similar vein, do not vent your dryer exhaust into the house. Some folks imagine they’re heating their home but they’re actually dumping water inside. Each dryer load contains 5-10 gallons of water. Just like the wood example, imagine dumping 10 gallons of water on your basement floor.

Household plants are another major source of interior moisture. All that water poured into the pots will evaporate. If you have high interior humidity, consider reducing the number of plants.

How to Control Humidity – Some Smaller Household Projects

OK, we’re through the habit items, onto household projects: first up, landscaping around your house. Anywhere the ground is level or slopes toward your house, rainwater will pool against the foundation.

As I’ve mentioned before, concrete is a giant stone sponge absorbing some of that rainwater into your basement. Landscape an aggressive slope to direct rainwater away from the house.

How to Control Humidity – Bathroom Fans

Hot showers and bath generate a huge amount of humidity. Bathroom fans move this swampy sauna air out of the house. If you have a fan, make sure you are using it. The simple addition of a timer switch (where turning on the lights starts the fan for a set period) can make this easy. If you don’t have a fan, consider installing a low some (quiet) model.

How to Control Humidity – Gutters

Installation of gutters is tied to controlling water around the foundation. A typical rain storm dumps hundreds of gallons of water on your roof system. This can saturate the surrounding ground, soaking into the porous concrete foundation. Use downspouts and extended drains which move rainwater away from the foundation, preferably toward a significant slope or a tree or brush root system.

Important note:
Ice dams can be a serious problem with houses in cold climates. They are formed when the top portion of the roof is above the freezing point and a lower portion is below the freezing point. Snow melts then re-freezes around the roof edges, forming an ice lip. Because gutters form a natural stop and freezing point, make sure that any ice dam problems are addressed before having gutters installed.

Gutters on a residential house

Lovin' me some gutters

How to Control Humidity – Kitchen Hood Fans

Kitchen hoods are another important tool for controlling moisture. The strong fan systems are mounted over your stove and vented to the outside. Picture a full stovetop with boiling pots filled with pasta, pasta sauce, green beans and rice pilaf. That’s four pans cranking out a ton of steam. An oven vent hood sucks this humidity up and pipes it outside. And don’t confuse these with microwave-based air recirculators which merely blow the air out their top.

There are tons of different ways to control your house’s humidity levels. So how do you control humidity in your home? Mechanical systems like dehumidifiers are expensive to operate. By using other approaches to minimize humidity, you can reduce the workload of your dehumidifier, and save money on your electric bill.

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