As the population continues to increase rapidly, the need for housing increasingly becomes a goal for governments. To provide accommodation, people are building using unique building materials that take a shorter time to complete.
Proper maintenance is required to ensure these buildings and houses last for decades.
One major factor is ensuring they remain dry to avoid dampness. However, dampness may affect poorly built or old structures.
In such a case, damp proofing treatment in buildings becomes essential to prevent health hazards to occupants.
What Is Damp Proofing?
Damp proofing is a construction technique that is used to prevent moisture from going through concrete and into interior spaces or the process of keeping walls, basements and floors dry.
It is important to note that damp proofing doesn’t keep all the moisture out. However, it slows down water penetration through concrete by blocking concrete capillaries.
Damp proofing is usually recommended in commercial buildings, but it is also acceptable in residential construction.
How Does Damp Occur?
Damp can be caused by so many factors, such as shoddy construction and defective materials. Some of the causes responsible for dampness in a structure include;
- Poor construction- a poorly constructed building with holes, defective roof joints, and improper connection of a wall's interlocking blocks will cause dampness.
- Defective building materials- some contractors use cheap materials that easily allow moisture through them. Such materials will cause dampness to walls, floors and ceilings.
- Moisture rising from the ground- there are instances where a building is constructed on land where the soil allows moisture to pass through and the foundation absorbs it. This causes dampness to the floor.
- Heavy rain shower- heavy rain pouring on a wall that is not properly protected becomes a source of dampness.
- Bad design- poorly designed buildings allow moisture to deposit on its walls and floors. The moisture comes from condensation.
What Are The Effects Of Dampness?
Building materials are not harmful under normal conditions. However, buildings with dampness are hazardous. Below are some of the effects of dampness;
- Pest breeding site- damp building creates a suitable environment for breeding mosquitoes and termites that will make the building unhealthy for occupants.
- The metal used in construction and concrete walls will be corroded.
- Dampness causes ugly patches on walls and ceilings and ruins the aesthetics of a building.
- It also damages wall decorations and paintings.
- It causes plaster to soften up and crumble.
- For houses built with timber, dampness causes rotting of the wood.
- It damages the floor by reducing the adhesion when moisture enters it.
- Dampness may cause outages or fires when it comes into contact with electrical fittings.
- Germs that are bred by dampness may cause diseases such as tuberculosis, rheumatism and breathing problems.
Damp Proofing Treatment In Buildings (5 Effective Methods)
There are several treatments and methods to prevent and maintain buildings affected by dampness. These strategies can prevent damages and rot to buildings.
Homeowners and contractors should always inspect their buildings for any signs. If dampness is detected and the durability of the building is affected, consider the following treatments and methods.
1) Membrane Damp Proofing
A more familiar name for this treatment process is the damp proof course (D.P.C). It involves introducing a damp membrane between the affected part of a building and the source of the dampness.
Flexible water repellent materials like plastic, polythene sheets, metal sheet, bitumen and mastic asphalt are used for damp membrane proofing.
See below general guidelines for using a damp proofing course;
- The materials should be used to cover the full thickness of the walls.
- To avoid damaging the damp proof course, the supporting mortar bed should be spread evenly without any projections.
- The horizontal damp proof course should be used on corners of walls and it should be continuous.
- Always ensure that each damp proof course that is placed relates correctly with the next damp proof course. This will ensure that you get a continuous and complete barrier that keeps the water out.
- Always cover the damp proof course to avoid exposure and getting damaged when you are doing your wall finishing.
2) Integral Damp Proofing
Another efficient method is integral damp proofing that involves mixing concrete and waterproofing compounds to form an impermeable layer.
The waterproofing additives that are used to include;
- Chalk, fullers earth and talc that fill the concrete voids
- Calcium chloride, aluminium sulphate and alkaline silicates that react chemically with the concrete to form an impenetrable layer.
- Oils, soap, petroleum and fatty acid compounds like ammonia and sodium that repel water. These compounds when mixed with concrete they form a water repellent layer that helps to deal with dampness.
- Other additives are silka and permo.
The quantities to be mixed with concrete are dependent on the supplier or manufacturer.
3) Surface Treatment
This damp proofing measure is the process of filling up pores of the walls, ceiling or surfaces affected by dampness.
Surface treatment works best when the dampness is mild and has just started to ruin the surface. This dampness corrective measure uses waterproof material made from water repellent additives like magnesium, zinc, soap and calcium.
The water repellent compound is applied on the affected surface where moisture enters. The process must be done carefully and it will be effective when the moisture is not under pressure and shallow.
Surface treatment also helps to prevent surfaces from raindrops.
For this damp proofing method, a cement gun is used to deposit a waterproof layer of rich cement mortar over exposed surfaces. The operation involves using the machine to force the cement and sand mixture through a 50mm pipe under pressure.
Before using the cement gun, ensure that you clean the surface removing any grease, dirt or unwanted particles. Once the surface is clean, wet it properly and then you can start guniting.
5) Cavity Wall Construction
As the name suggests, this method uses two walls and a cavity. The gap or cavity is left between the outer and inner walls. In a nutshell, cavity wall construction comprises the exterior wall, interior wall (the wall to be protected) and the cavity.
The cavity and the outer wall prevent moisture from getting to the inside wall. Also, the cavity offers good heat and sound insulation.
Be careful with this method as it requires extra care in its design and supervision. Otherwise, it won’t be efficient as an insulator against heat and heavy rain. Be sure to pay more attention to the top and bottom of the walls and the cavity openings.
What Materials Are Used For Damp Proofing?
Some of the best materials to use for damp proofing are;
- Rigid and impervious materials like slates mortar and bricks
- Mortar with water repellent additives like oils, soap, chalk and sodium
- Flexible materials including copper, bitumen, plastic sheets and butyl rubber
- Coarse sand layers placed under floors
- Others include stones and semi-rigid materials like mastic asphalt
Damp Proofing Advantages & Disadvantages
- Value addition– Damp proofing protects the structural integrity of your home. It makes it a safe place and therefore increasing its value.
- Prevention of health issues– this may be one of the most essential advantages of damp proofing. Avoiding the health issues caused by dampness and moulds like headaches, coughing and wheezing is a big plus.
- Easy to maintain– damp proofing methods are durable and do not require a lot of attention. They also help to fill cracks and voids that may have appeared on surfaces.
- Cracking surfaces– When damp proofing is not done correctly, walls or ceilings may develop cracks.
- High cost– exterior damp proofing methods and associated labour costs are typically pricey.
Frequently Asked Questions
What Is The Best Way To Damp Proof A Wall?
There are several methods but the most popular one is damp proof course method because it is flexible and easy to install.
What’s The Difference Between Rising Damp & Lateral Damp?
Rising damp is the movement of moisture or water from the ground going up walls of a building. While lateral damp is the penetration of moisture through walls, basically from outside walls to inner walls.
What Happens If Rising Damp Is Left Untreated?
It destroys your home’s or building's structural integrity and poses health problems.
Is Damp Dangerous?
Yes. As mentioned, it causes health issues and destroys surfaces.
Does Insurance Cover Rising Damp?
The simple answer is no since most home insurance companies don’t cover it. However, some insurers offer specific covers for rising damp.
Damp is a common problem in buildings and homes. You should inspect your home for any signs of dampness and moulds, especially if it’s an old structure.