CoatingsPro Magazine

JUL 2018

CoatingsPro offers an in-depth look at coatings based on case studies, successful business operation, new products, industry news, and the safe and profitable use of coatings and equipment.

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18 JULY 2018 COATINGSPROMAG.COM Specifying Success T here are a variety of divisions in a specifi- cation according to the Construction Specifications Institute. Throughout the spec, writers use something called legacy specifications, which continue to be used because they have worked for a long time. But as technologies change, so, too, should that portion of the project. One of the common legacy specifi- cations in Division 7, covering ermal and Moisture Protection, that can create problems with the long-term performance of air barrier assemblies and flashings is the architectur- ally specified use of water-repellent additives incorporated in the manufac- turing of CMU (Concrete Masonry Unit) back-up wall products. Substrate Suitability Originally, water repellents were developed to provide additional water intrusion protection. They may now work against newer, code-required building envelope technologies. For example, air barriers in Division 7 are now mandated by the International Energ y Conser vation Code (IECC) and are a baseline in Leadership in Energ y and Environmental Design (LEED) v4.0. Most f luid- or liquid-applied air barriers are water-borne, as are many primers used with transition membranes and f lashing. The use of a specified water-repellant additive in the CMU back-up wall substrate to which the air barrier is applied could cause: 1. A less-than-optimum adhesion of the water-borne air barrier to the CMU back-up wall substrate. 2. Blistering in areas of water-repel- lent-induced, non-adhered, fluid/ liquid-applied air barrier. 3. Non-homogeneous continuous film formation (think alligatoring or crazing). 4. All of the above, especially if the bidding documents specify a water- borne primer for flashings and/or sheet-applied air barriers. Code Compliance Some legacy specs, such as water-repel- lent additives, may no longer serve our new methods of construction. A nother example of an issue with a legacy spec comes from National Fire Protection Association (NFPA)-285: Standard Fire Test Method for Evaluation of Fire Propagation Characteristics of Exterior Non-Load-Bearing Wall Assemblies Containing Combustible Components. This code requirement has been around since before 2003, but it was not in the forefront of our thinking nor was it being enforced until recently. In the past, you could use any foam plastic insulation in a wall as long as it was a "Class A" material. In today's construction world, though, that is not true. For ex ample, cer tain insu lations used to be used universa l ly but are now restr icted to specif ic veneer/ façade desig ns. Be sure to research these t y pes of potentia l legac y problems. Most, if not a l l, commer- cia l ly avai lable r ig id foam plastic insu lation boards can comply w ith this requirement w ith some restr ic- tions. It became even more conf using when the air bar r ier became par t of the desig n parameters. e air barrier and insulation together must have either a listing with a manufacturer or a 3rd party engineer- ing judgment by a fire consultant to comply with NFPA-285. e easiest way to comply is by specifying an air barrier and insulation board from the same manufacturer. Although this may not be the best bidding situation for the owner, it is the safest way to ensure chemical compatibility and full compli- ance with NFPA-285. Chemical Compatibility Another consideration regarding legacy specs in the wall and air barrier realm is chemical compatibility, which is causing premature failures and accom- panying lawsuits. Today's wall designs have become a chemical soup of different product chemistries and technologies. If you have folks bidding your wall design, then make sure, as best as possible, that as many materials come from one source as is practicable. Two manufac- turers' products — or the adhesives used to adhere them — might not be chemically compatible. A n additional time-consuming step becomes obtain- ing letters from both manufacturers regarding their mutual compatibility and, of course, NFPA-285 compliance. T hese additional steps can present a great deal of jumping through hoops, loss of time, and possibly missed technical items, all leading to confu- sion and misinter pretation of that technical data. ese same chemical issues exist with through-wall flashings, which, in many cases, are not part of the air barrier assembly. Legacy specifica- tions generally specify the use of the By Roy Schauffele, FCSI, CCPR, FABA A, LEED Green Assoc., President and Founder of Division 7 Solutions, Inc. Legacy Specifications and Wall and Air Barrier Performance

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