Today’s post is about one such little detail. In this case the risk of its being a “big deal” is small but I have seen similar installations where, over time, considerable damage does occur.
This is a typical lead flashing common on houses in the Northwest.
The flashing is made of lead. It is designed to fit over the pipe and be lapped by the shingles on the plane of the roof. The cap you see on the top is a nice way to finish off the installation and is quite common when the roof portion of the flashing is not quite tall enough to extend to the top of the pipe. When it is tall enough, the excess above the pipe is simply folded inside the pipe. When the top is “counter-flashed” with this type of cap it is designed to lap both the outside of the lead flashing and the inside of the pipe. Without the cap, any water that hit the pipe would run down the pipe behind the lead flashing.
Now you might ask, well how much water could that amount to really?
If you look at this next picture you can see where the blue arrow points to two water lines that show how water hitting the inside of the cap is still finding its way outside of the metal flashing. The red arrow points to a water line that is clearly running down the pipe and into the roof/house structure.
In this next picture we can see “why” this is happening. When they installed the nice counter-flashing the piece that is supposed to be inside the pipe got scrunched and no longer directs water inside the pipe. While the blue arrows show where they have been “lucky,” the red arrow show where they have not been lucky.
In our area of the world, where it can rain or drizzle for weeks on end, it actually can result in a fair amount of water getting into the roof/house structure. Sometimes these vent pipes make an immediate right angle below the roof line to move over to where the pipe actually comes up through the house. There are lots of reasons why a plumber might do this. For example if the pipe would end up coming through the roof on the “street side” of the home, they will often run it to the back of the house where the pipe would not show.
At any rate, even a half a cup of water a day---or any amount that would not dry in 24 hours would keep ceilings below the leak wet and eventually cause damage to the ceiling. As a Licensed Structural Pest Inspector, this lack of attention to detail is what we would consider a “conducive condition.” A condition that if left un-repaired could result in wood decay/rot or promote infestation by wood destroying insects.
I have found several damaged ceilings with “unexplained” past/ongoing water damage from improper flashings around pipes. Repairs are a very easy fix, but certainly worth noting.
This defect, I might add, could likely not be determined from a ladder at the edge of the roof---another important reason for the home inspector to walk the roof when it is safe to do so.
Charles Buell, Real Estate Inspections in Seattle
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WA State, Home Inspector Advisory Licensing Board