Weather Testing Seeks to Improve BCSI

Originally published by the following source: SBC MagazineNovember 4, 2018
by Evan Protexter, P.E., Sean Shields and Kirk Grundal, P.E.

   

Since its introduction in 2003, the BCSI handbook has been the go-to resource for truss handling and installation guidelines. BCSI, which is based on the previous industry bracing document, HIB-91, contains recommendations and best practices that have been formed over years of working with trusses. These best practices are relied upon when making decisions about storing, handling, installing, and bracing trusses. While there is value in following a good set of best practices, SBCRI is looking to improve the knowledge behind BCSI’s guidelines in a way that only data gathered through testing can do.

It is known that weather affects trusses, but to what degree time and exposure to the elements impact performance is still quantitatively uncertain. As a current best practice regarding weathering issues, BCSI recommends covering the trusses if left exposed for one week as shown below in an image taken from page 4 of the 2018 edition of BCSI:

While BCSI gives guidance on how long to store trusses, this requirement may not always be feasible in the real world. Jobs go on hold, shipments arrive before the crew is ready, a rainstorm arrives before windows are installed. These are just a few examples of the many reasons a truss may be exposed to weather. BCSI as it currently exists provides the best approach garnered from anecdotal industry experience. As such, there is likely room for improvement using a scientific approach to measuring what happens to a truss when it is left exposed to the elements.

Improving the understanding of the effects of weather exposure will lead to a more comprehensive and science-based BCSI guidance. Through testing, SBCRI is looking to understand how not only length of storage, but method of storage relates to truss performance. Improving the knowledge behind truss storage methods and BCSI’s recommendations in general will allow component manufacturers and framers to confidently determine how to deal with stored trusses and all the considerations that should be taken into account when a just in time inventory approach to storing and installing trusses is just not possible.