Posted By Shaun Lundy I have noticed that there is difference between the standards for glazing thickness in the WHSWR ACOP and BS6262:1994, namely 12mm thickness for dimensions 3.00m x 4.50m in the ACOP and 4.50m x 4.50 in the BSI, with other ratios identical. I appreciate the status of the ACOP, however I cannot explain the obvious difference in the standards. Any ideas would be helpful. It has been suggested to me that this is a typo!!