Does a home inspector check the plumbing under the floor slab?
Thursday, October 25, 2018
There are two types of plumbing pipes under the floor slab in a modern “concrete slab on grade” home: pressurized water supply pipe and unpressurized drain pipe. Any leakage of the water supply piping, even a small fracture, causes visible problems pretty quickly--whether the leak is in a wall or under the floor slab--because the water pressure accelerates the damage, and we can locate the leak with an infrared camera. See our blog post How do you accurately find a broken water pipe leak under the floor slab? for more info on under-slab water pipe leaks.
But a defect in the drain piping, such as tree roots getting into the pipe or cracking from age or impact damage, can be harder to diagnose. We test the drain plumbing primarily by doing stress tests, such as turning on the bathtub and sink faucets and flushing the toilet, all at the same time. Or filling up a sink and checking for leakage around the collar, then opening the drain to look for leaks at the slip joints.
While our infrared camera will pick up drain pipe leaks located at, or just below, the floor slab but, for all practical purposes, once a pipe heads further down any leakage becomes less detectible with infrared.
But there is an alternative. If you have concerns about the underground drain piping, particularly the main drain pipe running from the house across the front yard to the sewer connection at the street, a good person to call is James Freeman, of J. W. Freeman Plumbing. His company, along with many other plumbers in the area, uses a plumbing snake with a video head to evaluate the drain piping in older houses. Starting at a vent pipe on the roof, James fishes the snake down through the house drain system and then out to the sewer connection at the street, checking everything from the inside.
That’s him in the picture above, doing a followup to a recent home inspection of ours, with homebuyer standing by and watching the video tour of his plumbing system. It can be entertaining to watch as he traverses the pipe bends, occasionally coming upon roaches scurrying away or looming tree roots. And you finish the video inspection with the peace of mind that your drain system is sound--or an additional line or two on the home’s repair list. You can contact James Freeman at email@example.com or (352) 316-3229.
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Here’s links to a collection of our other blog posts about PLUMBING PIPES:
How To Look At A House
McGarry and Madsen's home inspection blog for buyers of
site-built, mobile/manfuactured and modular homes
for Links to Collections
of Blog Posts