Damp Proofing

Damp proofing is a conventional method aimed at preventing unwanted moisture from infiltrating the interiors of buildings. Despite its common usage, the effectiveness and necessity of damp proofing are often disputed among professionals, particularly concerning the accurate identification of the root cause of dampness.

The Mechanics of Damp Proofing

Damp proofing typically employs a two-pronged strategy:

  1. Injection Treatment: This involves drilling holes and injecting a siloxane thixotropic cream or previously, silicone into the perps (spaces perpendicular between bricks) or bricks in a wall below floor level, aiming to reduce the wall’s absorbency. This can be done either internally or externally. The primary goal here is to impede groundwater from rising through the wall, although in reality, groundwater is seldom the actual cause of dampness.
  2. Plaster Replacement: The other aspect of damp proofing entails removing the normally absorbent plaster and replacing it with an impermeable slurry. This action supposedly masks hygroscopic salts, which are believed to emanate from groundwater, among other sources. However, in most cases, the underlying issue tends to be condensation, which proves to be a challenging and less commercially valuable problem to resolve.

The Misdiagnosis of Rising Damp

The misidentification of rising damp, which damp proofing seeks to address, can have various adverse implications:

  1. Undetected Root Cause: The real cause of dampness often remains hidden, leading to prolonged damage. For instance, in situations where condensation is the actual culprit, the reduced absorption in treated walls can exacerbate vapour absorption elsewhere in the building.
  2. Property Damage: Incorrectly diagnosed rising damp and subsequent damp proofing treatments can lead to damage to walls, plinths, and can be aesthetically unpleasing.
  3. Financial and Structural Implications: Damp proofing is not only expensive, disruptive, and messy, but its effects may need rectification within 10 to 20 years, despite the guarantees offered which rarely prove beneficial. Moreover, it’s likely to diminish a property’s value unless the true cause of dampness is correctly identified and addressed.
  4. Adverse Neighbourly Impact: Sometimes, the repercussions extend to causing dampness in neighbouring properties, thereby escalating the problem rather than resolving it.

Independent Professional Perspectives

A considerable number of independent professionals argue against damp proofing due to several reasons:

  1. Unlikelihood of Groundwater: Groundwater, being the supposed root cause of rising damp, is highly unlikely, rendering the damp proofing practice ineffective.
  2. Long-term Damage: By hiding the real issue, long-term damage continues unabated, sometimes even extending to neighbouring properties.
  3. Aesthetic and Structural Damage: Damp proofing can cause both aesthetic displeasure and structural damage, further lowering property value.
  4. Economic Burden: The financial strain coupled with the messiness and disruption during the process, and the probable need for re-treatment in the future, make damp proofing an unattractive option.


Damp proofing, though a common practice, seldom addresses the actual causes of dampness in properties, particularly in British urban settings. The focus should rather shift towards accurately diagnosing the root causes of damp, which will, in turn, lead to more effective and long-lasting solutions. This approach not only averts unnecessary financial expenditure but also preserves and potentially enhances the structural integrity and value of properties.

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