Recently we performed a pre-purchase inspection of a newer home that had a tremendous moisture problem. Upon entering the house, a wall of thick, humid air was unmistakable. Because that has potentially serious consequences to the structure and our client, we began searching for clues.

Where hot, wet air meets a cold surface, like a window or an un-insulated wall, it turns back into liquid water called condensation.

In this inspection, the aluminum sash, thermopane windows and the lower back corners of every closet’s exterior walls were affected.

Closets are notorious areas of poor circulation at best, but add high humidity to stagnate areas with cooler lower wall areas and you will get mold and mildew; that velvet- black, gray-green or pasty-white "munge" growing up the back walls. Besides damaging the wall surfaces, certain types of molds, called "Stachybotrys," are toxic and can be a very serious health hazard.

The next part of our inspection was under the house. Here we found the dryer vent lying on the ground, pumping hot moist air into a foundation area with far too few foundation vents and for who knows how long.

Spider webbing, another clue to high humidity, was very prevalent.

Our continued inspection led us to additional plumbing leaks, water inundation from downspouts that were too close to the foundation and a big hole in the down-draft fan vent from the Jenn-aire stove.

We also found some wood components damaged by some or all of these conditions. It was good that 6 mil. black plastic was on the ground or the damage could have been much worse.

The inspection proceeded into the attic. It was here that we found a humidity-caused situation, the likes of which we had never experienced.

The exposed undersides of the roofing paper was literally dripping wet – not from a roof leak, but from the moisture created by every shower that had been taken, at least that day, and by the fact that neither of the two bathrooms’ fans were vented through the new metal roof.

To add to this already bad scenario, the gable-end roof vents had been capped off with plywood leaving no chance for this daily addition of moisture to escape. Maybe that’s why they had to replace a 50-year shake roof in less than half its life!

Parts, or all, of this inspection example are all too common to nearly every house we have ever inspected. Our recommendations, which are always the same, need restating.

To stop the problems caused by moisture means preventing outside sources of moisture from coming in, conveying moisture created inside directly to the outside and monitoring these sources and mechanical solutions during your annual maintenance survey.

What’s a homeowner to do?

First, you may need to think differently about the simple acts that make your house so vulnerable to the cumulative sources of moisture.

Your should understand that dealing with every source of moisture counts, from daily baths, wet clothes and wet pets… to cooking, cleaning, and even the very breath of the occupants. The solutions are relatively inexpensive and will benefit your house as well as your health.

The simplest behavioral changes will go a long ways to protect both.

For instance, anytime a bath or shower is taken, leaving the bathroom fan on 30 minutes afterwards will remove most of the moisture in the air. If you don’t have a bathroom fan, vented to the exterior, install one as soon as you can. In the meantime, an open window will help.

After you’ve dried off, using your towel to wipe off the shower walls and door will remove a remaining source of a lot of water.

In the kitchen, whether you’re cooking a big pot of soup or boiling water for tea, all that steam going into the air is seeking a cold spot to turn back into water. Remember what we’ve told you about mold and mildew?

Unless the steam is removed by a vented fan, or even an open window, all that moisture will stick to the interior surfaces and act like an open invitation for mold and mildew to party at your house.

Again, leaving the kitchen fan on for a short period after the cooking is complete can make a world of difference.

Of course the same goes for doing laundry. Avoiding accumulations of wet towels or soaked jackets is good prevention. When you do tackle the laundry, stay alert to excessive moisture in the air, lint behind the dryer or steamy windows. These are clues that that the dryer hose has a tear or has come undone from its vent. This situation will need your immediate attention and repair.

What about those soaked boots and raingear? Establishing a routine of shaking off or wiping up as much water as possible, then leaving them in a ventilated area to dry is always a good idea.

Humidity is relative, but if it is raining in your house you have a problem.