Waterproofing is the process of making an object or structure waterproof or water-resistant so that it remains relatively unaffected by water or resisting the penetration of water under specified conditions. Such structures may be constructed in wet environments or underwater to specified depths. It makes impervious layer on a surface of structure.
Waterproofing in buildings and structures are generally required for foundation in waterlogging affected areas, retaining walls, underground and overhead water tanks, kitchen, toilets, bathrooms, balconies, decks, terrace or roofs, and swimming pools etc.

Here is some waterproofing methods are given which are used in construction :
1. Cementitious waterproofing
2. Sheet based waterproofing membrane
3. Liquid based waterproofing membrane
4. Cracks free silicon polymer based waterproofing

1. Cement based waterproofing :
Cement based products applied internally, externally or sandwiched within the structure.can be used for new build constructions.

This method is often used in the internal wet areas such as toilets. This method is usually a rigid or semi-flexible type waterproofing, but since it is used in internal areas such as toilets, it is not exposed to sunlight and weathering. Thus cementitious waterproofing does not go through contract and expansion process.

2. Sheet based waterproofing membrane :

Sheet Membrane
Al Bredenberg

These are membranes that arrive at the site in the form of rolls. These are then unfurled and laid on a firm surface. The most common type of sheet based membrane is a bituminous waterproofing membrane. This type of membrane is stuck to the substrate with a hot tar based adhesive using blowtorches. 
Self-adhesive compounds comprise asphalt, polymers and filler; additionally, certain resins and oils may be added to improve adhesion characteristics. The self-adhesive type has low shelf life as bonding properties of the membrane reduces with time.

3. Liquid based waterproofing membrane :

Liquid Waterproofing Membrane - MEL-ROL LM - W. R. Meadows

Liquid membrane is a thin coating which consists of usually a primer coat and two coats of top coats which are applied by spray, roller, or Brush.

These are generally considered to be superior to sheet based membranes as they are joint-free. However care must be taken in application to provide just the right thickness. The membrane can tear or break if it is too thin. The adhesion of the membrane to concrete must be good.

4. Cracks free silicon polymer based waterproofing :
Silicone Polymers can offer higher flexibility. which are then either sprayed or brush-applied on the surface.4 Coat Application.The liquid cures in the air to form a seamless, Cracks -free membrane. The thickness can be controlled by applying more of the liquid chemical per unit area.

Waterseal PSv is a heavy duty durable terrace waterproofing system. composed of specially developed highly elastic & durable Silicone polymers, incorporated graded fillers, light fast & weather durable, micro-fibers, additives. Is suitable for both indoor & outdoor Roof and sealing work.

Waterproofing methods are applied in the following parts of a building:

  • over terrace slabs and balconies
  • in toilets
  • underneath and around basements
  • in concrete water tanks (use a food safe membrane)
  • in swimming pools
  • over landscaped concrete decks, between the soil and concrete
  • ​in gutters

Check for the following properties of the membrane:

1. UV Stability - if the membrane is to be exposed to the sun, than it must be UV stable or UV resistant, else it will degrade over time.

2. Elongation - this is the ability of the membrane to stretch. It is measured in percentages. An elongation of 150% means that the membrane can stretch to 1.5 times its length when pulled. Elongation is a must in buildings that will move, such as high-rise buildings, or buildings made with steel, which is flexible. This property will allow the membrane to stretch over cracks that may develop in the future. Membranes with elongation properties of over 200% are available.

3. Breathability - one disadvantage of good waterproofing is that if water does happen to enter into the structure from a point and spread across a surface, that water is trapped inside the structure, and cannot get out. Breathable membranes help to release that water to the air in the form of water vapor. So some membranes are designed to prevent water from passing through them, while at the same time allowing water vapor to pass through. So over time, breathable membranes allow trapped water to evaporate into the atomosphere.

4. Tear Resistance - this is an important property, as many membranes that have good elongation also can tear easily. Take a small sample of the material in your hand, and try and tear it into two pieces. This gives a fair idea of its tear resistance. You are looking for a membrane that will not tear even if a reasonable force is exerted on it. 

5. Abrasion Resistance - this is the ability of a membrane to withstand wear and tear. As most membranes are covered concrete screeds and tiling, the abrasion resistance comes into play during the construction period, when workers are walking on the surface, dropping nails and screws, and scraping hard objects like rebar against the membrane, which can damage it. A very soft membrane with low abrasion resistance may get damaged in such a situation, which can cause it to leak.

6. Chemical stability - check that the membrane is chemically inert with respect to its environment in the building. Some membranes, especially outside basement walls, are exposed to the soil and rainwater outside.


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