How to Find Sewer Line Under Concrete Slab
Mostly, houses built on a concrete slab have concrete columns and beam around the edge that is typically about 600mm wide. The concrete slap on the floor that sits on a compacted gravel foundation is usually 100mm to 150mm thick and has wire mesh (BRC) with steel reinforcing bars within it (reinforced concrete). This concrete slap is often called a floating slab because it ‘floats’ on the soil.
In many homes, sewer and drainage pipes are often placed below this slap or within the slap, and sometimes even the electrical circuitry has to be placed in before the concrete slab is poured. Therefore, it means that these pipes and drainage channels are basically embedded into the slab, and if pipes are damaged, and you want to replace them totally, you will have to cut the slab and dig them up.
How to Locate Pipe Under a Concrete Slab
Bathroom and Kitchen remodel in houses built on concrete slabs floor presents a huge and unique set of challenges, especially when locating in the home’s sewer line. Cutting into the slab at the precise location will keep the schedule intact and costs down.
But then, how do you go about finding the sewer line location on the slap?
Here is a device called Pipehorn that can be used(video below). The device emits a signal through the line that can be read by a wireless receiver.
You start by running a fish tape through the sewer line, which he then hooks up to the Pipehorn transmitter.
The Next step is to tune the receiver’s frequency, then use it to trace the path of the pipe in either direction of the line.