UL Standards free download UL 10A-2009 pdf download – Tin-Clad Fire Doors UL 10A-2009 pdf download - Tin-Clad Fire Doors. 3.6 The actual thickness of the boards shall be not less than 3/4 in (1 9.1 mm). 3.7 The boards shall not be less than 4 in (89 mm)... 02-11 Download Now