Lateral Damp

What is Lateral Damp?

Lateral damp is the ingress of ground based moisture migrating horizontally through a permeable structure normally associated in subterranean walls found in cellars and basements and/or in walls that were previously situated above ground level that have been subsequently covered by soil/aggregates when elevating ground levels for example to create driveways, parking and/or for decorative purpose such as flower beds. In such circumstances the raised ground level will permit moisture to saturate masonry or bridge the horizontal Damp Proof Course (DPC), thereby compromising the building’s defences. 

In both cases ground water will travel horizontally, until it reaches an exposed surface, where it will disperse or evaporate. 

Water content increases as it descends through the substrata, as a result lateral damp (or water ingress) becomes more severe the deeper an excavation. Other factors affecting lateral damp will include water and soil types. 

Lower water tables and well drained ground present a more benign environment for combating lateral damp, high water table/less permeable soil. 

What are the signs of Lateral Damp?

  • Discolouration and/or damage to internal surfaces rendering, plasterwork, decor and/or woodwork situated in the vicinity

Note: Lateral Damp is often misdiagnosed or misinterpreted as rising damp as both are closely associated with lateral damp migrating horizontally through the walls and rising damp migrating vertically within the walls.

Is Lateral Damp a problem?

Lateral Damp is only considered a problem where the area of property in question is needed to be used for storage and/or habitation. 

Where pressurised water ingress is occurring the external diversion or drainage is impracticable for example in civil engineering project such as tunnels it may be possible to deploy highly specialised solutions involving extreme water leak ceiling techniques. 

Later Damp for example in storage or habitable areas may resolve by installing a continuously sealed proprietary impervious membrane system referred to as tanking to the floor and wall surfaces situated below ground level and where applicable incorporating a horizontal damp proof course designed to prevent the migration of gtound based moisture into the internal environment. Where water ingress is involved more sophisticated interventions may include a water sump(s) and pump(s) to designed to disperse water from behind the tanking system out to the exterior. The most robust solution is the dispersal of water before it reaches the outer wall. Such outcomes may be achieved by the installation of an external sacrificial wall system which will protect vulnerable walls within the property against lateral damp (prevention is better that the cure). 

If you experiencing such problems
an ISSE Member may be able to help

If you would like to learn more
take a look at our training courses.