Tracer gas leak detection beneath a solid wall

An ADI investigation at an old town house believed to be Grade II listed. Tracer gas and acoustic equipment located a leak on the cold mains beneath a solid wall between two rooms.

Water moving with nothing turned on

The property was empty, and the combi boiler had been drained down. At the external meter just outside the property, the engineer saw constant movement with nothing in use. The meter showed a leak rate of approximately 1 litre per minute.

The internal stopcock could not be found, and the customer did not know where it was either, so the water could only be isolated at the external meter.

Narrowing it to the cold mains

The engineer isolated the cold feed to the boiler and checked the meter again. It was still moving, which pointed to a leak on the cold mains inside the property rather than on the hot water side.

Tracer gas and acoustic leak detection found the leak

With the water turned off at the external meter, tracer gas was added to the cold pipe under the kitchen sink. Scanning the rooms, the engineer quickly picked up gas between the living room and dining room, coming from under a solid wall. A large damp patch was creeping up the wall in the same area.

Acoustic equipment confirmed that the leak was in this area, and the engineer could also hear it by ear.

Photographs from the visit

These are ADI’s photographs from the same visit. They show equipment used during the investigation, not a repair.

Acoustic listening equipment on the floor beside a damp wall corner and a dark timber post
Acoustic listening equipment in use beside a damp wall during the visit.
A moisture meter held against damp plaster beneath a dark timber beam
A moisture meter against the plaster during the visit. Its display is not a measurement of the leak rate.

Why the repair waited

A repair was not carried out at this visit. The report records that the wooden floor would need to come up in this area, and that because the property was believed to be Grade II listed, clarification was needed on what could be done. The customer was advised to contact their insurance company to assess the next step.

No repair or retest is recorded for this visit, and this account does not describe what happened afterwards.

For another building, the proposed work and its permissions need their own assessment. Read about planning access for an investigation and checking listed building consent.

About this case

This anonymised account is based on ADI’s engineer report and photographs from the visit. The report says the property is believed to be Grade II listed; that has not been independently verified here. Names and the property’s location are omitted.

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