Take a look at this home's roof, covered with fresh snow. You can see a wide band where a large amount of snow has prematurely melted, the result of heat escaping from the home (up go the utility bills). This early melt will refreeze when it gets down to the gutter line. This is the birth of an ice dam and the start of a whole lot of moisture problems. If this is your roof, it needs better ventilation. That ice dam was just your first headache.

Here's one of the classic symptoms of in-home moisture problems: water leaking in through the basement foundation blocks. Many people think this means the water must be coming from the ground through a leak in the foundation itself; but this isn't always the case. Water from higher up, like from an ice dam, can intrude into the house walls and drip down through the wall cavities until it hits bottom - the basement block - and has nowhere else to go. This water can be drawn back into the home through the block and result in stains like these.

Here's where old "conventional wisdom", in hindsight, turned out to be not so wise. It used to be that everyone was gung-ho to put vapor barriers everywhere, including between the upper level ceiling and attic floor. But this allows rising moisture nowhere to go... except back down. The force of the moisture pressing back with nowhere to go over time is what's peeling this closet ceiling's paint. Yes, those are giant paint chips. Moisture, as a rule, needs a way to go up and out if you want to avoid this sort of predicament.

Look closely. The white paint at the front of this house is peeling. Why? Same principle as with the attic above. Here, the trapped moisture made it to the attic, but there isn't sufficient ventilation to allow it past the roof. Therefore, in an effort to escape, the moisture will push out through the attic walls... and through this force over time, peel the exterior paint. Going another direction, this same process will cause shingles to cup and curl and bring your roof's useful life to an end in a relative hurry.

It's not just the paint job the suffers when trapped moisture tries to force its way past the wall, it's also the wall itself. When the structural members are saturated with excess trapped moisture for long enough, they're going to start rotting. Behind the sheathing paper of this wall from which the ruined, paint-chipped siding has been pulled away, you can see the wood has rotted to the point of breaking up and creating holes in some places. This saturated part of the wall and everything that went over it - siding, paint, etc. - must be replaced.