Leak Inside a Wall? Who to Call and How It Is Found

In older houses the pipes to a bathroom, a radiator or an outside tap were chased into the brickwork and plastered over. In newer houses and in most refurbished bathrooms they sit behind plasterboard, in stud walls or behind tiles. Either way, the pipe is hidden and the first warning is usually on the wall surface. Paint bubbles, plaster softens, a tide mark appears, or the grout darkens behind the shower. Sometimes there is a faint hissing with the house quiet. Many people call a plumber first, and a plumber will often say the leak needs to be located before it can be fixed.

The difficulty is that water inside a wall rarely stays where it leaks. It runs down the back of plasterboard, follows the chase, soaks along a course of bricks and comes out at the lowest or thinnest point. A stain at skirting level can come from a joint a metre above. A damp patch in a hallway can come from the bathroom on the other side of the wall. Opening the wall at the stain often finds wet plaster and no pipe, and a second and third hole follow. Each hole is more making good, and the leak is still running.

We start by finding the pipes. The thermal imaging camera shows hot pipes inside a wall and the cooler, wetter area where water has spread. A moisture meter maps how far the damp runs. For the cold mains the acoustic microphone listens on the wall surface for the sound of water under pressure. Where the pipe is silent, we drain it and introduce hydrogen tracer gas. We then sample the wall surface, the skirting and the tile joints until the detector finds the gas. The gas is a tracer only and this is not gas-safety work. If you ever smell gas, leave the property and call the gas emergency number.

Once the leak is pinpointed, one small chase is opened at the mark, usually a few tiles or a patch of plaster the size of a hand. The pipe is exposed, the fault photographed and, if you want, repaired in copper or barrier pipe on the same visit. Tiles stay on everywhere else. Your written report records the thermal images, the moisture readings and the location, which is what buildings insurers expect to see for a trace and access claim. If a wall cannot be read without opening it, for example behind a thick tiled render, we tell you that before we start.