Quotations for steel windows often say "TATA steel" without saying how thick it is. The thickness — the gauge — decides how strong, how heavy and how long-lasting the window is.
What the gauge number means
The higher the gauge number, the thinner the sheet. For steel windows and door frames in Kerala the common sizes are about 18 gauge = 1.2 mm, 16 gauge = 1.5–1.6 mm and 14 gauge = 2.0 mm. Always ask for the thickness in millimetres — it is easier to check than a gauge number.
Weight and strength
- Weight: a 1.6 mm frame uses about a third more steel than the same frame in 1.2 mm.
- Overall stiffness: a folded frame in 1.6 mm is about a third stiffer than in 1.2 mm.
- Dents and buckling of flat faces: resistance grows with the thickness cubed — 1.6 mm is more than twice as resistant as 1.2 mm.
- Welding: thicker sheet takes welding heat without burning through or distorting, so corners stay square.
What it costs
Steel is only part of a window's price — hinges, handles, cutting, welding, finishing and labour are the same whatever the gauge. In our costing, moving a typical three-shutter window from 1.2 mm to 1.6 mm adds well under 10% to the finished price.
Which to choose
For frames that carry shutters, grills and doors — and for a house you will live in for decades — 16 gauge (1.6 mm) is the sensible choice. LINEA uses 1.6 mm TATA Galvano with a 120 GSM zinc coating as standard. You can check the thickness yourself on any sample with a vernier caliper; remember the zinc adds a few hundredths of a millimetre.