How To Look At A House

McGarry and Madsen's home inspection blog for buyers of  

site-built, mobile/manufactured 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:

Why is my roof sheathing sagging between the trusses?

Why is granule loss a problem for an asphalt shingle roof? 

What would cause a home inspector and roofing contractor to disagree on the remaining life left in a roof?

What are the mistakes to avoid when doing attic improvements?

What causes roof shingles to curl up at corners?  

What causes shingles to buckle along a line on the roof?

What causes leaks at a fake roof dormer? 

What causes a sagging roof ridge line?

What causes bubble-like blisters in a built-up and gravel roof?  

Why does it cost so much more to replace a steep roof than a low slope roof? 

What is "ponding" on a flat roof?

Is an attic required to have a light by the building code? 

How can I inspect my roof for hurricane damage?

Why is premature curl of roof shingles a problem?

How can I tell if a roof has more than one layer of shingles? 

What are the common problems with attic insulation? 

What is the life expectancy of an asbestos cement shingle roof? 

What's the average lifespan of a roof?

Why is it a mistake to replace a roof and not replace its flashings? 

Why is there no attic access hatch in the house?

What is the building code requirement for an attic access hatch, scuttle, or door? 

Does a roof with multiple layers of shingles last longer?

What can I do to prevent roof leaks?

Are roof trusses better than roof rafters (stick framing)? 

Why is a popped nail in a shingle roof a problem? How do I fix it?

What are the most common problems with wood roof trusses?

What causes a lump or dip in the roof? 

If my roof is not leaking, why does it need to be replaced?

How can I be sure my roofing contractor got a permit?

How many layers of roofing are allowed on a home? 

What are the dark lines running parallel to shingles on my roof?

Can metal roofing be used on a low slope/pitch roof? 

How can I make my roof last longer?  

What are the warning signs of a dangerous attic pull-down ladder?

How can I find out the age of a roof? 

Should I buy a house that needs a new roof?

Should I buy a house with an old roof? 

What are those metal boxes on the roof?

What does "lack of tab adhesion" in an asphalt shingle roof mean?

Why do roof edges start leaking?

Why do my dormer windows leak? 

Do home inspectors go on the roof? Do they get in the attic?

Should I put gutters on the house? 

How much of a roof truss can I cut out to make a storage platform in the attic? 

What's the difference between an "architectural" and a regular shingle roof? 

What does a home inspector look for when examining a roof? 

Do stains on the ceiling mean the roof is leaking?

How can I tell if the house needs a new roof?  

 Why does my homeowner's insurance want a roof inspection?

What are the hazards to avoid when going into an attic? 

    Visit our ROOF AND ATTIC page for other related blog posts on this subject, or go to the INDEX for a complete listing of all our articles.

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