Some newest waterproofing materials for roof
Roof slab is prone to direct atmospheric changes which lead to severe rainfall and structural movements.
The roof of a building should be designed and constructed in an efficient manner through adequate large rainwater pipes to ensure that the rain is discharged d from the building without inducing dampness in any segment of the walls, roof or foundations of the building or an adjoining building.
Preferably, the concrete is considered as extensively and regularly applied construction material that is presumed to be water resistant with co efficient of hydraulic permeability among 10-8 to 10-10 m/sec. A well-made concrete with correct mix design and pouring and curing practices is treated as a very low porous material. However, practically it is found that concrete drops its permeability.
Concrete is naturally weak in tension; cracks and voids can also develop because of thermal expansion, contraction and shrinkage. Consequently, water will penetrate through these voids. So, waterproofing is essential to retain the roof water-tight as they are uncovered to the weather.
While construction process is going ton, proper care should be taken to resist unnecessary moisture from being trapped among the reinforced concrete roof structure and membrane. Due to this, flat roof waterproofing failure happens frequently.
With the progressions in chemicals and better greater conception of construction materials, various types of water proofing methods are emerged out. The methods which can provide maximum protection to the roof should be chosen.
Given below, the details of some newest waterproofing methods with their broad chemical compositions :-
- Hot applied bituminous materials: Bituminous substances with fabrics or felts
- Cold applied bituminous materials: Asphalt emulsions or asphaltic mastics, reinforced with fabric
- Liquid applied membranes: Single or multi-component products like neoprene, neoprene-bituminous blends, polyurethane, polyurethane bituminous blends, and epoxy-bituminous blends. Epoxy emulsions facilitate the concrete to exhale but not permit rainwater penetration.
- Sheet-applied materials : Neoprene, Butyl, EPDM, PVC, etc. which are attached with adhesive sealing or chemical welding (solvent bonding).
- Cementitious membranes The thickness of membrane can fluctuate according to the type of material, its physical and environmental exposure, and loading conditions. Generally, the waterproofing membrane is used to give protection to roof from water. The membrane should be safeguarded from traffic and weathering. On the basis of the material types, the roof waterproofing systems are categorized as follow :
- Liquid applied membrane system (LAM)
- Prefabricated or preformed membrane system (PFM)
Roof Membrane System
The waterproofing membrane is treated as the most vital element of the roofing system as it primarily discharges water from the building. Some of the most recognized waterproofing membrane methods are liquid applied waterproofing membranes and pre-formed sheet waterproofing membranes.