Preventing Hidden Leaks in Outdoor Plumbing

Due to a leak in the outdoor plumbing, the corner of the house had rotted beneath the shingles.
wood rot

"We never saw a leak, but over some years the entire corner of the house had rotted beneath the shingles." —Patty O'Donnell

"During renovation, we’d created a drain beneath new patio stone, and installed a hand-held shower for rinsing beach sand off kids and dogs. We shut the water off before frost each year, and all seemed well until my son gave the dog a pre-season, early spring bath. When he went to shut the water back off, he discovered a cascade in the crawl space under the shower." —Patty O’Donnell

The Fix for Rotted Wood

When the shower apparatus was removed and the shingles taken off, the picture underneath wasn’t pretty. The corner sill and post, the wall sheathing, and even some fir porch decking had rotted. All the compromised wood, much of it “the texture of a rotten zucchini,” had to be cut out and replaced. Carpentry was the easy part. But what had gone wrong? 

Several mistakes were made from the get-go. The water lines and shower plumbing were located in an exposed corner of an unheated crawl space, with a turnoff in the cold zone and no good way to flush remaining water from the pipes. The shower fittings were a cheap indoor set: Apparently, their (former) plumber had said, “Nothing will hold up, so don’t spend a lot of money, just get used to replacing it.”

When it did fail—either from metal fatigue or a frozen pipe—the leak was undetectable from outside. Due in part to inadequate flashing, water was running into the corner of the house, hidden by shingles and sheathing, invisible unless someone were lying in the crawl space while the water was on. Annual inspections were not held. Years passed.

After the carpentry repairs, the fix should include using exterior grade brass fittings and better flashing. The plumbing fittings may be frost-resistant, but even the best are not frostproof: all it takes is one unexpectedly cold night for a pipe or fitting to burst. So the new valve and shower set should be removable. The plumbing can be configured so that the homeowner can disconnect it from inside and just slide it out from the exterior, to be stored and replaced for the winter with a blind cover made of painted AZEK. 

And since someone has to turn the water on and off anyway, he or she should have a helper on the outside. Then the person inside can check for occult leaks—every spring and fall.

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