The Problem of Indoor Moisture
by Building Inspector and Indoor Air Specialist, Dan Schilling
© Copyright 2002 Residential Inspections LLC, All Rights Reserved
Where does indoor moisture come from?
Indoor moisture can come from bathing, cooking, dishwashers, refrigerators, clothes washers and dryers, humidifiers, leakage and seepage from plumbing fixtures, leaky tub and shower wall enclosures, roof leaks, ice damming, condensation, migrating vapor penetration, basement floor leaks, foundation leaks, failed caulking, loose flashings, improperly installed windows, defective siding, poor attic ventilation, and improperly vented furnaces, water heaters and fireplaces. In short, there are plenty of moisture sources and areas where moisture can reveal itself within a home.
What are the evidences of moisture in a home?
Evidences most commonly include water stains on structural components and building materials within a home. A musty smell in a home is also a warning of an active moisture concern. Mold growth is another visual evidence of a moisture condition which should be looked into further. Loose wall tiles, cracked or missing grout and failed caulking in bath enclosures can also indicate the possibility of moisture damage within an interior wall. Often homeowners have no idea of hidden moisture problems until a trained inspector examines the home. When hidden moisture is discovered during the inspection, it may reveal a larger concern that is not readily visible.
When a moisture condition is discovered in an attic, basement, or on a wall or ceiling, it is a sure sign of a problem desperately needing a solution. For example, what appears to be a very minor problem on the outside of a wall can turn into a major repair problem on the interior of a wall cavity. Moisture problems do not get better by themselves; they only get worse and more expensive to repair as time goes on. The first concern is to the property itself regarding the rotting of building components. The second concern and perhaps the most important is the issue of health. If not promptly corrected and dried, moisture conditions can lead to serious mold contamination problems in as little as 48 hours.
How exactly does moisture cause a problem?
Moisture can affect indoor air while in a vapor form, but most commonly the serious problems begin when condensation of moisture occurs. At this point it can affect the structure, as well as, the air.
During mold investigations I have seen moisture condense on all sorts of building components and personal property. The colder the surface of a building material or piece of personal property, the more likely moisture will condense on it. I have witnessed moisture condensing on personal belongings kept in basements, on interior walls, and inside of wall and ceiling cavities. I have even seen it literally raining "inside" of attics due to escaping house moisture that had condensed on the underside of attic sheathing. The condensation had formed ice 1/4 inch thick on the underside of the roof. After the attic temperature warmed up, the ice began to thaw and it rained in the attic so much that water was coming through the ceilings!
Ultimately, wherever there is condensation indoors, you will find a mold problem. This is due to the fact that mold spores are everywhere in indoor environments and so is mold food. All that is missing is moisture. When the moisture arrives, the mold contamination begins.
If you are purchasing a home or will be continuing to live in a home that has any evidences of moisture problems as mentioned above, contact a home inspector who specializes in this area to have those suspect areas properly evaluated.
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