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Of all of the defects we look for in a home inspection, moisture is always the one that causes the most concern. Moisture is one of the worst enemies your home can have. It can cause your clothes and furnishings to mildew, ruin interior surfaces, reduce the insulating value of your insulation, cause squeaky floors and nail popping, cause paint peeling and stains on the walls and ceilings, and can ruin the structural frame of your house through fungus growth and rot.

Moisture levels in a home depend on a variety of different factors such as lifestyle (showering, cooking, heating and cooling), number of occupants, leaks and ground/atmospheric moisture. Moisture wants to move from areas of high vapor pressure to areas of low vapor pressure. Vapor pressure is the pressure exerted by water molecules in a mixture of air. When a home is being heated, moisture wants to move outside, and when it is being air-conditioned, moisture wants to move inside.

Since Central Oregon’s climate is generally dry during the summer months, moisture in homes during this period is usually caused by plumbing problems or building envelope (roof, window and wall) failures. The most destructive leaks are the slow leaks that go unnoticed for a long time. These can occur under sinks, behind dishwashers and refrigerators, and in bathrooms, or long term exposure to sprinklers. This creates a perfect environment for bacterial growth. While not all mold is toxic, it can lead to musty odors, deterioration of the house, and aggravate people with allergies.

Moisture in building materials can destroy structural integrity and nurture mold. The first step in moisture problem remediation is to quickly and accurately locate and remove all sources of moisture. Infrared cameras can show you what’s wet and what’s dry by highlighting differences in temperature due to thermal mass variations. IR cameras can help find the ultimate source with little or no physical disassembly of the premises and minimal disturbance of inhabitants.

What can you do to control moisture?

Bathroom vents can remove excess moisture from showers and baths. Often people do not use the bathroom fan because it is noisy, or they don’t want to let it run while they are gone from the house. We recommend using it! If not, leave the door open when you are done. Closing the door traps moisture in you bathroom which can cause a lot of problems. One great solution is to install a timer switch to control the fan after you exit the bathroom.

Kitchen vents, if vented to the outside, can remove excess moisture from cooking. Range hood fans that vent back into the room can remove smoke and odor by passing the exhaust through a filter, but they do not remove moisture from steam. If your house or condo is small, and you have a recirculating vent (one that blows back into the kitchen), be sure to leave a window open.

Clothes dryers that are not vented properly can produce large amounts of moisture in a house or garage. We recommend that you do not use a lint trap. These are considered a fire hazard, and they allow lots of warm, moist air into you house or garage. Even if your dryer vents to the outside, periodically check the duct for obstructions or built-up lint. This is a fire hazard, and can lead to blockage which will force the dryer to vent into the house.

Ventilation of your garage, crawlspace and attic are a must. Do not block the vents in your garage. There are several reasons for this. In many houses the furnace, water heater, and washer and dryer are located in the garage. These all create heat in addition to parking a car in the garage. If moisture is present you can create a perfect environment for mold. Be sure you have enough ventilation for your crawlspace and attic. The general rule is that you should have one square foot of ventilation of every 150 square feet of crawlspace or attic space. If you have had a room addition added to your house, be sure proper ventilation was installed.

Another big help in avoiding moisture problems is drainage, both around and under the house. This includes rain gutters and proper grading which direct water away from the structure. Good drainage will get rid of surface water and high ground water before they become a moisture problem. If you house has a raised foundation, consider installing a vapor barrier on top of the dirt.

Many homeowners will experience high humidity conditions in a new home the first year it is occupied. One reason for this is the amount of water that is present in the paint, plaster, concrete and other building materials. This moisture must be evaporated before the house thoroughly dries out. This problem usually corrects itself after the first year. If it does not and moisture problems persist, look for other causes of moisture problems and then correct them.

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Moisture is the most destructive force