Damp Proofing Methods, Advantages, and Disadvantages

What is Dampness?

Dampness is a common issue with most properties; especially older ones that lack the modern-day damp-proofing. Although tiny patches of dark mold on the walls may not demand your attention; if you don’t fix things, things could escalate quickly.

Untreated dampness can lead to mold and mildew growth, unpleasant smell, poor quality air, health issues, structural problems, and poor-looking indoors.

In this post, we look at what causes dampness and how different damp-proofing courses can tackle this common household issue.

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Causes of Dampness

Essentially damping happens when the moisture is locked/absorbed by the building material. Since most materials are granular, it’s easy for water and moisture to find an easy way via the voids. When you throw capillary action in the mix, it further allows the moisture to make way across different directions in walls and floorboards.

Generally, damping finds its way through the interiors of a house; either via floor, roof, or walls.

Common causes of damp are –

  • Use of low-quality construction materials
  • Bad structural design
  • Faulty construction
  • Exposure to rainwater on the outer walls, causing the water to lock-in
  • A low-quality roof that doesn’t keep the rainwater from entering the house
  • Faulty junctions joining the roof slabs
  • Small roof slopes
  • Leakage through down passes

Common Damp Proofing Methods

Damp-Proof Course (DPC)

A DPC is a membrane that acts as a barrier against moisture. It is laid in the walls of the property generally 150 mm above the ground level. This prevents the damp from rising through the surface walls. Slates, pitch, asphalt, bitumen, and low absorption bricks have been commonly used as DPC through the years.


Cavity walls

A cavity wall is exactly what it sounds like. It’s essentially two parallel walls/skins that are separated by air space between them. There are 3 parts to a cavity wall – outer leaf, air space, and inner wall. It’s not necessary for the leaves forming the cavity to be the same thickness.

Cavity walls are excellent in that the outer wall efficiently prevents moisture from traveling through the inner wall. Cavity type construction is the ideal kind in hot-dry and hot-humid areas.

Surface Treatment

Surface treatment involves filling up the surface pores that are subjected to moisture and dampness with water repellent materials. Generally, this involves using water repellant soaps like aluminum oleates, calcium, and stearates to protect the building against heavy rainfall. Transparent coatings, varnishes, paints, cement coating, and bituminous solutions are all part of this category.


Guniting consists of applying a rich layer of cement mortar. This layer is deposited over the surface to act as a barrier against water. A cement gun is used to carry out this operation. The entire assembly entails a machine that mixes different materials followed by a compressor. The compressor pressure mixes the material via a flexible hose pipe with a 50mm diameter.

At the free end, there’s a nozzle through which water pressure is supplied via a separate connection. Before beginning the surface treatment, it is important to clean the walls thoroughly. Cleaning removes any loose particles, dust, grease, grime, dirt, etc. Because of pressure application, the material is densely compacted and adhesion is strong.

Silicone Damp Course

Silicone damp course is primarily a kind of wax that carries strong water-repellent properties. As part of the damp-proofing course, it uses fluids mixed in a spirit base to further render antifungal property.

Plastic Sheets

Plastic sheets are a common DPC material that is essentially all-black color polythene. In terms of thickness, it can be anywhere from 0.5 mm- 1 mm. Plastic sheets are applied directly to the wall.

Advantages of Damp Proofing

  • The #1 advantage of DPC or damp proof course is that it eliminates humidity and maintains the quality of air. You can prevent myriad health issues by avoiding moisture build-up.
  • Mold and mildew can cause a musty and pungent smell to form around the house. This can sometimes be too much to handle. DPC ensures that mold doesn’t form.
  • Damp proofing course improves the life of the paint on walls.
  • It keeps the structural integrity of the walls intact.
  • Application of DPC maintains the value of the property.
  • It prevents dry and wet rot from happening.
  • It cuts down on the cost of timber replacement, floorboard replacement, and myriad other repairs/fixes in the long-run.

Disadvantages of Damp Proofing

  • At times during the damp-proofing process, normal cracks can develop.
  • Often DPC can lead to leveling problem
  • It’s not uncommon for DPC to create ugly patches around the walls.
  • It adds an additional layer of weight to the structure.


Installing a DPC around the house is one of the best decisions you can take to safeguard your property. It will improve the life of your house while also avoiding ugly patch formation.  It’s a great investment in both long and short-term.