Waterproofing is the combination of materials used to prevent water intrusion into the structural elements of a building or its finished spaces. Its main purpose is to resist hydrostatic pressure exerted by moisture in the liquid state. Hydrostatic pressure is pressure exerted by a fluid at equilibrium at a given point within the fluid, due to the force of gravity.
Torch-On Bitumen Membrane Waterproofing
Torch-On Bitumen Waterproofing remains the most important base material for waterproofing today. Flow resistance over a temperature range of zero to ninety five degree centigrade is a prerequisite for South African conditions. Torch-On Bitumen Waterproofing is particularly required with the increase in the use of thermally insulated roof decks.
Torch-On Bitumen Waterproofing is perfect for the waterproofing of roofs on buildings due to being:
- Inherently waterproof.
- Elastic due to vastly improved elasticity that moves with the structure thus capable of accommodating thermal movements of roofs.
- Durable with an extremely long life span.
- Excellent adhesive properties.
- Flexible at low temperatures, which enables laying in cold weather.
- Strong, which allows for a single ply application.
- Resistant at application temperatures to permanent deformation, puncture and tear.
- A good ‘walk on’ property during and after application.
- Capable to bridge movements of cracks and joints in the substrate and better fatigue resistance.
- Liquid and will always find applications.
- A readymade membrane that eliminates uneven substrates that are virtually impossible to apply uniformly as some areas will have product in excess of and others less than specification, which could have been weak and problems could have occurred.
- Not too rigid.
- Protective for buildings.
- Harmonious with its environmental surroundings. It has a low carbon footprint as it is a hydrocarbon and it is created naturally from crude oil.
Advantages of Torch-On Bitumen Waterproofing include:
- Does not generate greenhouse gases.
- Sustainable way of storing carbon on the earth’s surface.
- Different mineral finishes can be applied to the top surfaces.
- Does not release harmful toxin.
- Does not affect human health as fumes given off during installation are not harmful.
- Low noise pollution during application.
- Bituminous membranes protect insulation and reflect harmful sun rays.
Cementitious waterproofing is the easiest method of waterproofing in construction. Cementitious waterproofing is often used in the internal wet areas such as toilets. Cementitious waterproofing 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. Cementitious waterproofing does not go through contract and expansion process. Cementitious waterproofing is manufactured from materials containing portland cement-based compounds with proprietary chemical additives to affect curing, strength, and chemical resistance.
There are two categories of Cementitious waterproofing materials:
- Cementitious Waterproofing Coatings
Cementitious waterproofing is similar to most non-cement based waterproofing materials. It is applied to a concrete or masonry substrate, which includes stone, brick, tile, cast concrete, pre-cast concrete, concrete block, asbestos-cement board, renderings and plasterboard. It forms a barrier to water penetration. This method of waterproofing is a barrier directly bonded to the substrate, to form a tight matrix that covers the pores in the substrate.
- Crystalline (or Capillary) Waterproofing
Crystalline waterproofing compounds chemically react with chemical compounds in concrete or concrete masonry to seal the naturally occurring pores found in concrete materials to prevent water penetration. The chemical reaction is dependent upon a proprietary chemical catalyst in the mix, which causes chemical compounds in the concrete pores to crystallize and become plugged to prevent water passage.
Cementitious and crystalline waterproofing can be used above or below grade, and on interior or exterior surfaces. Cementitious waterproofing consists of portland cement-based compounds with proprietary chemical additives to affect curing, strength, and chemical resistance.
Cementitious waterproofing is used in the following type of structures:
- Water Treatment Plants
- Sewage Treatment Plants
- Railway & Subway Systems
- Marine Cargo Ports & Docks
- River Locks/Channels & Concrete Dykes
- Parking Structures & Lots
Polyurethane Resin Liquid Membrane
Polyurethane liquid membrane method of waterproofing is used for the flat roof area and exposed to weathering. The Polyurethane resin liquid-applied waterproofing membrane is particularly suitable for roofing applications, possessing high strength, high elongation and good durability under outdoor weathering conditions in a broad temperature range. Polyurethane Liquid Membrane can offer higher flexibility.
Waterproofing membrane is a thin coating which consists of usually a primer coat and two top coats which are applied by spray, roller, or trowel. Liquid waterproofing membrane offers more flexibility than the cementitious types of waterproofing. The liquid cures into a rubbery coating on the wall. The elongation properties of the coating can reach as high as 280%. The durability of the waterproofing coating depends on what type of polymer that was used for the making of the liquid waterproofing.
Waterproofing membrane can be of spray-applied liquid membrane composed of polymer-modified asphalt. Polyurethane liquid membranes are available in separate grades for trowel, roller or spray.