Salt air and steel
Within a few kilometres of the sea, salt carried on the breeze settles on every surface, and Chennai's humidity keeps it damp. In reinforced concrete, salt and moisture work their way to the steel bars. The steel rusts, the rust takes up more room than the steel did, and the concrete cover cracks and falls away. Brown streaks under balcony edges and broken cement balusters are the usual signs.
GRC is reinforced with alkali-resistant glass fibre spread through the whole section, not steel bars. There is nothing inside it to rust.
How we detail it near the sea
- Stainless steel anchors and brackets for fixing elements to the building.
- A breathable sealer or exterior paint on exposed faces, renewed like any exterior finish.
- Occasional rinsing to clear salt deposits, which helps any finish last longer.
The northeast monsoon
Chennai gets most of its rain between October and December, often in heavy, wind-driven bursts. Materials that soak up water suffer: POP mouldings soften and crumble outdoors, and cement mouldings run by hand on site tend to crack along their length, letting water in behind.
GRC is a dense, cement-based material made for outdoor use. What keeps a facade clean in the monsoon is how water is shed, so we build that into the castings.
How we detail it for the rain
- Drip grooves under cornices, sills and copings, so water falls clear instead of running down the wall.
- Sloped tops on bands and parapet copings, so water doesn't sit.
- Sealed joints between elements, with corners cast in one piece where possible.
Sun on the west wall
West-facing walls take the full afternoon sun. Glass on those walls lets the heat straight in; a solid wall closes off the breeze. A jali sits between the two: it shades the wall and the window behind it while air keeps moving through, and turns direct sun into a moving pattern of light.
For larger buildings, facade panels with deep window reveals and fins do the same job at a bigger scale, shading glass from the low east and west sun.
See GRC jali and GRC facade panels.
Cyclone winds
Elements high on a building, such as domes, minarets, parapet balustrades and large facade panels, have to stay put in cyclone winds. GRC's light weight helps, but what matters most is the frame and fixings behind it.
Those are designed by your structural engineer for the site's wind load under the Indian wind code, IS 875 (Part 3). We provide element weights, sizes and fixing details for that design, and fix to it on site.