The safety regulations for critical area glazing have an exclusion clause that says that traditional stained glass windows and leaded light panels do not have to be toughened safety glass because of the small panes of glass used. Also there is no thickness requirements in stained glass panels.

If I am concerned about a stained glass window I am fitting then I will either put a piece of toughened glass at the back of it or seal it into a triple glazed unit.

You can find out more by visiting www.stainedleadedglass.co.uk