Is it true that single seal units will not meet the Standard?
No. The pass/fail criterion is based on the amount of water vapour which penetrates the sealed edge. This will depend on the sealant thickness, the amount of desiccant used, and the quality of the corners, among other considerations. In general, some of the single seal polysulfides, polyurethanes, and silicones may have difficulty in meeting the requirements. However, you should also bear in mind the use of the product, in respect of its size, location, and the chosen glazing method. While hot melt butyl and PIB based systems will pass more readily as single seals because they are not cured, there is a limit to the size which can be safely made.
