Polyurethane Waterproofing Treatment
Polyurethane is made up of two components, base and reactor. Polyol acts as the base, while isocyanide is the reactor component. The combination of both these in a specific design ratio creates a liquid coating for waterproofing applications. Polyurethane is a rather popular choice due to its ease of installation. Unlike other waterproofing systems like sheet membranes and liquid applied membranes, this polyurethane application requires comparatively less skill and supervision. Application is fast and this type of treatment can be used for post construction applications aswell.
Detailed methods for surface preparation and application are prescribed by the product supplier and often supervised by them in large project applications. Waterproofing is an expensive business, still it is better to prevent leakages and take all precautions during construction stage itself.
Advantages of Polyurethane waterproofing systems:
- Easy and fast installation
- seamless finish
- Long term durability and wear resistant
- UV and weather resistant
- Resistant to alkaline cleaners, battery acid and fuels
Polyurethane Waterproofing Procedure
- The roof surface is thoroughly cleaned and is made free of any foreign matter
- Any cracks on the surface preparation bed is cut to V section, cleaned and filled with a 1 part polyurethane based crack filling compound and 2 part white cement (1:2)
- The surface must be neutralized by removing alkalinity through the means of acid application
- A two pack polyurethane primer coat is first applied to the surface to serve as an adhesion coat. It is allowed to dry for at least 8 hours.
- Three successive finishing coats are then brush-applied, each with 2 component polyurethane mixed as per design ratio. Each coat is allowed to dry for at least 12 hours before applying the next.
- The PU coating is continued 150 mm up the parapets or walls. It should also be continued at least 100 mm into the rainwater pipes
- The final Polyurethane coat is sprinkled with a layer of 300 micron of sand
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