Havering Glass keep a close eye on all Glazing manufacturing to ensure that we use only the latest technologically designed glass. Following the 2002 version of the glazing standard has made a dramatic shift from sixty-second to a three-second length duration glass loads. However, an addition to the ASTM E1300 standard presents further additional load duration factors that go from three seconds up to beyond a single year for the glazier. In another addition, further instructions have been given on combining loads of different duration periods. The standard does not consider every glazing design situation.
For situations not normally addressed by the standard, glaziers are advised to get a design professional who will use glazing engineering analysis and judgment to determine the required load resistance of the glass. There are several key terms that are regularly used in ASTM E1300.
• Glass type factor.
This is usually defined as a multiplying factor by adjusting the load resistance of several different glass types.
• Specified design load.
This is the power in pounds per square foot, type of load,and duration of the glazing load given by the specific authority.
• Load resistance.
This is the uniform leveling load that a glass construction sustains based on any given probability of glass breakage and load duration. If the glass load resistance is less than the specified load, then all other glass types and thicknesses may be checked out and evaluated.
Because the glass strength is so important, the designs of any building, both regarding structural performance and also building code compliance, has been widely used and referenced. While some glaziers have expressed a desire for a easier approach to determining al glass strength. Most glaziers, including us at Havering Glass, agree that the additional charts are really helpful because they provide much-needed guidance and information in all areas that are not previously covered by the standard.
One subject now being considered by the glazing task group is the equivalency of all types of laminated glass interlayers made with polyvinyl butyral. The task group intends to provide glazing guidance on this subject in all future editions of the standard as a means of enabling glazing designers, building officials, and the glazing industry itself to understand better the performance issues that surround the use of glass in buildings.