How to Waterproof your Terrace using Waterproof Coatings

Waterproofing an existing terrace/roof slab 

 

Materials required

1. Latex polymer which can be used both as a primer for the top coat and also for preparing a polymer modified repair mortar. 

2. Ordinary Portland Cement (OPC).

3. Acrylic Top Coat  (Waterproof Coating)- Acrylic polymer modified coatings have extremely good UV resistance and crack bridging abilities. Some acrylic top coats also have additional benefits such as heat reflection.

4. Mason's Tool Kit.

Surface Preparation

. The cement surfaces must be cleaned free of loose materials, oils and other contaminants.
. Check the screed for hollow spots using the wooden handle of a hammer. 
. Any sections found to be hollow (screed de-bonded from the mother slab) must be repaired using a polymer modified mortar.
. All surface cracks must be checked for integrity. Any loose cracks must be chipped and repaired using a polymer modified mortar. Cracks that are not loose and not greater than 2mm can be filled using a crack filler. 
. Rinse the surface with clean water to remove any dirt. 
. Saturate the cement surface with water. Saturation prevents the coatings from curing prematurely due to absorption of water.  

Application 

. Apply a coat of primer which penetrates the porous surface and seals the pores and allows for good bonding of the protective top coat to the cement substrate. Priming can be achieved using specialized primers or using latex polymers diluted to the specified consistency. 

. In the case of latex primers, while the primer is still tacky (after approximately 30-45 mins, depending on the surface temperature) apply the 1st coat of an acrylic top coat. For other primers follow the manufacturer's instructions.

. After the 1st coat has cured for about 3-4 hours, apply the 2nd coat in a direction perpendicular to the direction of application of the first coat. In case of large roof spans, a glass fiber mesh can be embedded between the 1st and 2nd coats by loosely laying the fiber mesh on the cured 1st coat and then applying the 2nd coat on top of it.

. A 3rd and final coat can be applied after about 6-8 hours.

The above system can be left exposed and no screeding is required for low - medium foot traffic. The above system has a life expectancy of about 5-10 years depending on the foot traffic.