Two ways to close a balcony
Most flats in Indian cities close their balconies and windows mainly to keep children and pets safe. For decades the answer was a mild steel (MS) grill. Today many homeowners ask for an invisible grill instead.
Both do the same basic job. They differ in what you see, how long they last and how much work they need. This guide sets out the differences so you can choose with your eyes open.
What an invisible grill is
An invisible grill is a row of thin stainless steel wire ropes stretched across an opening. The ropes are typically SS 316, about Ø2 to Ø3 mm, and often nylon-coated. They are held in aluminium tracks fixed to the wall, floor or ceiling, and pulled tight.
The ropes can run horizontally or vertically, on balconies and on windows. The gap between ropes is typically 50 to 75 mm for child safety. From a few metres away the ropes almost disappear, which is where the name comes from.
What an MS grill is
An MS grill is a frame of mild steel bars, welded and painted. It is strong and familiar, and any fabricator can make one. But it is heavy, it blocks a large part of the view, and it needs repainting at regular intervals.
Mild steel also rusts. In coastal cities such as Mumbai, salt in the air speeds this up. Once the paint cracks, rust streaks can run down the façade and the bars slowly lose section.
Side by side
An invisible grill does not turn a balcony into a cage. It keeps the view and the breeze, which is usually why people choose it.
| Invisible grill | MS grill | |
|---|---|---|
| Material | SS 316 wire rope in aluminium tracks | Mild steel bars, painted |
| View and light | Largely open | Partly blocked |
| Airflow | Open | Reduced by the bars |
| Painting | None | Regular repainting |
| Sea air | Does not rust like MS | Rusts once the paint fails |
| Weight | Light | Heavy |
| Gap | Typically 50 to 75 mm | Depends on the design |
What makes an invisible grill safe
Safety comes from three things: the gap, the tension and the fixings. The gap must be small enough that a child cannot put their head through. The ropes must be tensioned so a push does not open the gap much. And the tracks must be anchored into sound concrete or masonry, not just plaster.
Rope grade matters too. SS 316 contains molybdenum and resists salt air much better than lower grades, which can stain near the sea.
- Ask for the rope grade and diameter in writing.
- Ask what gap the grill will have, and measure it on site.
- Ask how the tracks are fixed, and into what.
- Check with your housing society before you change the look of the façade.
Acier invisible grills: Jakob ropes
Acier invisible grills use Jakob AISI 316 stainless ropes with Jakob terminals, each rope tensioned on its own. Jakob is the Swiss rope maker founded in 1904, which Acier has represented exclusively in India since 2014. For homes with young children we recommend vertical ropes at a 50 mm gap.
For larger openings, or where a whole building wants one uniform look, Jakob Webnet stainless steel mesh is another way to close a balcony. It is a fine rope mesh with a sleeve at every crossing, so each opening keeps its shape.
How Acier can help
Acier surveys the opening, recommends the rope, gap and layout, supplies the materials and installs the grill, with one point of responsibility from measurement to handover. We are based in Mumbai and work on homes and residential towers across India.
