This post came just in time for Thanksgiving a few years ago—and I am thankful for that!
I got a call from a very nice lady I met at my doctor’s office. She wanted to talk to me about a water leak on her back deck. She was having a difficult time figuring out where the water was coming from and, so far, after many months, no one she had consulted with had come up with a satisfactory answer.
She said that the roofer couldn’t find anything wrong with the roof and her electrician, a plumber, a pest control operator, a jack-of-all-trades person and a very cleaver son-in-law couldn’t figure it out either.
She was at her wits end by the time she called me to see if I had any ideas. I asked her a few questions to try and eliminate a few of the possibilities. After all, figuring this sort of thing out is a process of elimination–it is never going to be rocket science no matter how illusive or elusive the answer may seem.
I told her I had some time the next day, and I would stop by her house with my moisture meters and brain and see if I could figure it out.
She informed me that whenever it rains really hard, or for a long time, the wet spot shows up and gets worse the rainier it gets. Well that sure sounds like a roof leak, doesn’t it? In this picture you can clearly see the wet spot and it most certainly tested “positive” for moisture with my moisture meter.
There was a toilet on the other side of the wall in the area of the wet spot, so the bathroom, while not a great suspect, was a possible suspect too. But investigation of that area turned up nothing out of the ordinary and what the heck would a leak in the bathroom have to do with rain?
I checked the attic in the area above the wet spot. But again, nothing consistent with past, present or ongoing leaking could be found.
The moisture meter could find nothing in the wall near the wet spot and all the flashing details of the deck attachment to the house seemed well done—a lot better than most decks I see.
As you can see in the next picture, the ceiling of the roof that covers this deck is vaulted and there is virtually no way wind is going to blow water into this area—especially given that this spot is not on the side of the home that is most exposed to the prevailing winds and weather.
It was an opportune time to figure out the problem because Seattle had been in a monsoon for several days and it was raining hard when I got to her house.
The deck surface is a composite-type decking and the deck has a very long set of uncovered stairs that go down to the back yard. These stairs are actually the first clue as to what is going on–even though they are quite a distance from the wet spot.
Since I was just about out of ideas and I had already opened myself up to ridicule by stating that the solution was not rocket science, I was starting to think that perhaps I was going to have to eat the whole rocket!
Suddenly it all came together in a flash that I am sure it would not have come to me “after” turkey dinner.
However, I have to think that the anticipation and planning for the cooking of my 26 lb Thanksgiving turkey must have played a critical part in my epiphany.
I turned to her, and with some trepidation asked, “Do you keep a bag of salt where that wet spot is–for the stairs in the winter time?”
I knew instantly from the expression on her face that I had indeed hit upon the answer. In fact the ultimate “taste test” confirmed that the wet spot was indeed salty. The wet area gets bigger the more it rains because there is more moisture in the air to be collected by the salt. The wet spot was purely hygroscopic and getting rid of the salt deposit will get rid of the wet spot.
But now I need to get back to the “very clever son-in-law.” He perhaps came the closest to a possible answer with his guessing that perhaps it was a raccoon marking his territory–that would indeed be another way of getting salts to the area. Now I am having second thoughts about that “taste test.”
Sometimes you have to think outside the turkey!
Thanksgiving is just around the corner already.
By Charles Buell, Real Estate Inspections in Seattle
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