Rising Damp

rising damp on common passage wall
rising damp in a tenement
rising damp in external wall

Rising damp is the name given to a slow upward migration of dampness up a wall or ground supporting structure, groundwater rises by moving up through interlinked masonry pour structures via capillarity action which over comes the effect of gravity. For it to occur there must be a sufficient source of groundwater and the absence of a damp proof course or some other barrier for instance slate in the mortar bed or dens stone or brick work.

 The height of is controlled by the thickness of the wall, masonry pours size and the amount of water at its base and if rate of surface evaporation is reduced it can rise until it can no longer overcome gravity.  

Black speckled mould growth rising from floor level is not rising damp it is caused by atmospheric moisture.

Is there a cure

YES: At the time of construction prevented by installing a physical barrier called a Damp Proof Course. In Edinburgh, I have seen this work in building work from 1830. This is why it’s so unusual to find in a well-built building.

What happens if I think I have rising damp”

Arrange for an inspection by a suitably qualified surveyor as it is more than likely you have a more common type of damp.

When it has been diagnosed?

  • Install a remedial chemical damp proof course to control the groundwater by controlling capillarity movement by fluid injected under pressure or cream injected into the mortar joints. 
  • Install a remedial electro-osmotic system to control the rising groundwater by reversing its flow. This is a scientific method of dealing with rising damp.
  • Drain the ground around the property.  This may not be practical and needs to be monitored.
  • Cut into the walls and install a physical damp proof course, but this could affect the building structure.