Thinking out of the envelope about your envelope
With the increasing demands of building-code officials and the expanding scope of limitations placed on the building community by government environmental agencies, the work of product developers and formulators continues to become more difficult.
Innovation through Regulation One specific limitation is related to the allowable level of volatile organic compounds (VOC) in architectural coatings. This product classification includes many of the common roof coatings that are available in the Canadian market today. The following chart describes the current limitations as described by the Canadian Environmental Protection Act. In many cases, the concentration limits are derived from limits developed in the U.S. Current changes are underway in the U.S. to further reduce the allowable VOC in architectural products. If history is an indicator, the new VOC limits will soon 22
Ops Talk • Spring 2014
become part of the Canadian standards. (Depending on which side of parliament you are on, this could be a good thing or a bad thing.) Regrettably, this can make formulating useful products more difficult.
Description1 Thermoplastic Rubber coating and mastic, incorporating no less than 40% by weight of thermoplastic rubbers in its total resin solids, for application to roofing or other structural surfaces. Metallic pigmented coating, containing at least 48 g of elemental metallic pigment per litre of coating as applied Bituminous roof primer Any other bituminous roof coating Non-‐bituminous roof coating, for application to roofs to prevent penetration of the substrate by water or to reflect heat and ultraviolet radiation
reduce the viscosity of the applied product and allow for ease of application; and in some cases, the leveling properties of coatings. As the levels continue to become more restrictive, it becomes more and more difficult to produce an effective product. Simply “taking more solvent out” becomes an unviable option. Many formulators over the past several years have explored and implemented the use of “exempt solvents”. Exempt VOC Concentration Limit (g/L) 550
500
350 300 250
VOC, although not completely accurate, is synonymous with solvent. Solvent is the carrying media for the proper application of each of the described architectural products. The solvents work to
solvents are considered to be lower ozone “depleters” than alternative solvents. There are few exempt solvents that are a proper fit for use with roofing products. The more common choices include TBAC (tert-butyl acetate), DMC
