Frequently Asked Questions

What surface preparation is required on a 10-year-old cement plaster external facade with multiple hairline cracks and chalky surface before applying Sikagard 550 W Elastic?

A 10-year-old cement plaster facade with chalky surface requires thorough preparation before Sikagard 550 W Elastic application — the elastomeric coating relies entirely on adhesion to the substrate for its crack-bridging and waterproofing to function, and a poorly prepared surface is the primary cause of delamination and blistering failures. Required preparation sequence: High-pressure water washing: wash the entire facade with a pressure washer at minimum 100 bar pressure to remove loose paint, chalky cement, dirt, biological growth (algae, moss, lichen), and surface carbonation. Allow to dry for 48 to 72 hours after washing. Crack treatment: cut all visible cracks above 0.3 mm width to a minimum 5 mm wide x 5 mm deep V-groove using an angle grinder with diamond blade; fill all cut grooves with Sikaflex 221 polyurethane sealant; allow sealant to cure 24 hours before coating. Remaining hairline cracks below 0.3 mm are within the crack-bridging capability of Sikagard 550 W Elastic at the specified film build and do not need individual treatment. Missing or loose plaster: cut out and replace loose, hollow-sounding plaster areas with 1:4 OPC:sand mortar render flush with the surrounding surface; allow to cure minimum 14 days before coating. Primer: apply Sika Concrete Primer or Sika Primer W (suitable for masonry and concrete surfaces) in one brush or roller coat and allow to dry (2 to 4 hours at 30 degrees C) before applying Sikagard 550 W Elastic.

How many coats of Sikagard 550 W Elastic are needed for waterproofing a 15-storey RCC-framed building external facade and what is the coverage per litre?

For a 15-storey RCC-framed building with concrete columns, beams, and AAC block or brick infill walls, the recommended application system for Sikagard 550 W Elastic is two coats of the main coating plus priming, following this sequence: Coat 1 (Sikagard 550 W Elastic): apply by long-pile roller or airless spray at wet film thickness of approximately 600 to 700 microns (coverage approximately 1.4 to 1.7 m2 per litre at this wet film); allow minimum 4 to 6 hours at 30 degrees C before Coat 2 (check that the first coat is touch-dry — does not transfer to touch). Coat 2 (Sikagard 550 W Elastic): apply in the opposite direction to Coat 1 to ensure uniform build, at the same film thickness; total dry film thickness after two coats should be 600 to 800 microns. For the 15-storey facade, budget approximately 0.7 to 0.8 litres of Sikagard 550 W Elastic per m2 of coated area (both coats combined, accounting for substrate absorption and normal roller/spray wastage). For a typical 1500 m2 total facade area on a 15-storey residential building, estimate 1100 to 1200 litres of Sikagard 550 W Elastic plus primer. At junctions between concrete frame members and infill block walls (column-wall and beam-wall junctions), embed 50 mm wide Sika geotextile mesh into the first wet coat to reinforce the coating at these high-movement interfaces before applying the second coat. Contact Space Arc Engineering for a complete facade waterproofing specification and quotation for your building project.

Can Sikagard 550 W Elastic be applied during the monsoon season in Delhi NCR and what are the temperature and humidity limits for application?

Sikagard 550 W Elastic is a water-based coating with specific temperature and humidity constraints for application. Minimum substrate and ambient temperature: 5 degrees C (well above the winter minimum in Delhi NCR). Maximum substrate temperature: 40 degrees C (applies to direct solar-heated facade surfaces in May to June). Maximum ambient relative humidity at the time of application: 85 per cent. During the Delhi NCR monsoon season (July, August, September), the ambient relative humidity commonly exceeds 80 to 90 per cent during rain events and for several hours after rainfall — during these periods, application of Sikagard 550 W Elastic should be suspended. The practical approach for monsoon-season facade work in Delhi NCR is to apply Sikagard 550 W Elastic only during the dry intervals between rain events — typically mid-morning to early afternoon on days with no forecast rain, when the facade surface has had time to dry from the previous day or night rainfall. Check that the plaster substrate is genuinely dry by placing a small polythene sheet against the wall face: if the underside is condensation-free after 30 minutes, the surface is dry enough to coat. Do not apply within 24 hours of rain on the substrate surface or when rain is forecast within 4 hours of application (before the coat is rain-resistant). Monsoon-season facade waterproofing projects in Delhi NCR require flexible scheduling and crew readiness to work on suitable days, rather than fixed daily production targets.