Voluntary Guidelines for IGU Cavity Width Manufacturing Tolerances

The cavity width of an insulating glass unit (IGU) after fabrication varies based on changes in temperature, barometric pressure and elevation above sea level. The purpose of this guideline is to present voluntary manufacturing tolerances for IGU cavity width reduction at the point and time of IGU manufacturing. The guideline is not intended to address the dynamic aspect of cavity width variability once an IGU leaves the point of manufacture where environmental changes occur. Nor does this guideline address naturally occurring solar reflectance.


IGMA is the trade association representing the interests of the Insulating Glass industry not only in North America but worldwide. Our focus is on developing and advancing new technologies in the manufacture of insulating glass units through development of codes and standards, topic industry publications, education, product certification and leading edge research.