Sleuthing out moisture problems We noticed some water stains around our house. How can we determine if they are new or left over from an old, and hopefully remedied, problem?
—RICHARD LOSPINOSO, CHATHAM, NJ
TOH building engineer Ross Trethewey: It’s smart to pay attention to water stains; when left untreated, minor leaks can lead to mold or cause major damage to insulation and other building materials. Finding the source of the problem can be challenging because stains can be caused by a host of different exterior issues, such as a missing roof shingle or a cracked boot on a vent pipe, or by interior problems like a leaky pipe or condensation on metal ducts. Often, the source of the leak is a distance away from the stain. Fortunately, there are some simple tools that can help you identify the leak and trace it back to the source.
A thermal camera may be the most convenient detection device, but it’s also one of the most expensive. Starting at around $300, these long-range scanners are standard gear for home-energy assessors; these technicians rely on thermal cameras to quickly inspect walls, floors, and ceilings for temperature fluctuations. Because wet material will be at a different temperature, a leak will show up as a blue patch, as shown above. Although the camera is easy to read, it’s not perfect. A cold spot like this one could be water, missing insulation, or even a hole in the siding or sheathing, so more investigation would be necessary.
Although they aren’t able to scan walls as easily, electronic moisture meters can quantify moisture levels, enabling you to measure the extent of the damage and identify the wettest section in order to track down the source of the leak. There are pinless and pin-type meters. Pinless meters start at about $50, but pros prefer them because they don’t damage walls or woodwork. Pin-type meters send an electric current between two sharp pins that must be pressed into the material being scanned.
It helps to know what the numbers mean, and when you need to worry. Under typical conditions, moisture-content levels for drywall should range from 6 percent to 9 percent,
