How To Look At A House
McGarry and Madsen's home inspection blog for buyers of
site-built, mobile/manfuactured and modular homes
How does a home inspector find roof leaks? What about wet spots in the walls?
Friday, October 19, 2018
Back when we were building contractors in Key West, the #1 roofing contractor in town was a guy named Michael Chodzin. He had been doing roofing since the 1970s, and the slogan on the side of his trucks said “Chodzin Roofing - We Are Smarter Than Water.” Ask most anybody in town for the name of a good roofer, and Michael sat at the top of the list.
Seemed like a truly dumb business promotion to me. Smarter than water? But he was proud of his slogan and, after years of dealing with moisture intrusion problems in homes, I realized that water is—if not smart—at least very sneaky and hard to predict. Turns out, being smarter than water is not easy.
Let’s start with the science. Water has three different states according to it’s temperature, each with different physical properties: liquid, solid (ice), or gas (vapor).
Liquid water rolls downhill due to gravity, right? Yes, except where capillary action, the phenomena you see when a sponge sucks up water out of a puddle, comes into play. And, of course, wind-blown water in a storm can be pushed upward six inches or more into any unsealed opening in a home’s exterior, where capillary action sometimes takes it anywhere else it wants to go.
Then there’s ice. Most materials shrink when frozen, but water expands. And it expands with tremendous force. This is the property that causes ice dams along the edge of roofs in colder northern climates that back up and leak into a home.
And finally, there is water vapor to consider. House-wrap material, which is applied over wall sheathing of a house under construction before the siding is applied, is specifically designed to deal with the perplexing issue of water vapor movement through walls and it’s tendency to condense back to liquid form when it reaches a colder surface. Modern house-wrap allows water vapor to pass through, but not liquid water, because trapped water vapor that condenses inside a wall create an insidious mess.
In our job as home inspectors, what we call “water intrusion” (water that gets into a home at a place it’s not supposed to be) is the one defect that can cause the most expensive repairs. Mold, wood rot, crumpling drywall, electrical shorts, and a myriad of other problems follow. A good roof is the first line of defense against water, but well-sealed exterior walls and good plumbing are important too.
One of the tools we use to look for water in the home’s envelope is an infrared camera. Unlike a regular camera, which sees light, it sees heat in the form of the temperature of the surfaces it scans. Because water that gets into a concealed area of the home will start evaporating almost immediately, and the evaporation cools the area around it, the camera is able to spot abnormally cool areas for further probing and evaluation.
After a scan with this hi-tech tool, the next weapon in our water-fighting arsenal is our fingers, which, like everyone else’s, are sensitive to moisture at a touch. Then there’s our moisture meter, an electronic device that measures the percentage of water in a material.
Finding water intrusion is difficult, but figuring out how it got there is sometimes even more complicated. Michael Chodzin always had amazing stories about how he tracked a roof leak back to it’s source that had stumped lesser tradesmen.
Being “smarter than water” is a big job, but we’re on it. Michael died several years ago, but we remember him fondly—always with a laugh—and talk about him often.
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To learn more about roofs and attics, see these other blog posts:
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