This standard provides a code of practice for patent glazing systems, which are non-load bearing systems of glazing bars and glass used for roofing and wall cladding. It covers material selection, design criteria including wind loads and water drainage, and guidelines for workmanship and installation.
Code of practice for patent glazing
Quick Reference Values
Maximum deflection of glazing bar under wind loadSpan/175 or 20 mm, whichever is less
Minimum recommended slope for sloped glazing5 degrees (approx 1 in 12)
Maximum recommended unsupported length of glass pane2.5 m
Minimum bearing of glass on glazing bar10 mm
Key Formulas
pd = k1 * k2 * k3 * Vb^2 — Design wind pressure calculation (reference to IS 875-3)
Z = (w*L^2)/8*fb — Required section modulus of glazing bar
Practical Notes
This standard has been officially withdrawn by BIS. However, its principles are still valuable as a reference in the absence of a direct Indian Standard replacement for traditional patent glazing.
The most critical design aspects are ensuring adequate water drainage and providing for thermal expansion and contraction of the glazing bars and glass to prevent leakage and failure.
Modern facade designs often use more advanced curtain walling or structural glazing systems, which are covered by other national or international standards.