I saw a catastrophic failure waiting to happen during a drive through New Brunswick a few days ago (September 26, 2020). A barn roof that was sagging a good 10 feet in the middle. For sure, a barn that was no longer in use because of the risk. <\/p>\n\n\n\n
Of course I added it to the list of failures I posted last July 23 that are everywhere in the built environment. (Ref. 1) <\/p>\n\n\n\n
It was the magnitude of the sagging ridge that caught my eye. Even at a distance it was easy to imagine, maybe just see the bulging eaves. The eaves of a roof bulge out when the ridge sags.<\/p>\n\n\n\n
You see lots of large and small buildings in the country with roofs that are sagging a little or a lot. Many are abandoned, but not all. And some are only a few years old, not gray with age and many decades old.<\/p>\n\n\n\n
You can also see buildings in town – houses, for example – with sagging ridges. A tiny sag, a few inches at most, just enough to catch your eye from the street.<\/p>\n\n\n\n
The large sags are probably due to inadequate design of the roof trusses or the rafters. Many of the tiny sags are design failures too. <\/p>\n\n\n\n
But some tiny sags are due to green lumber shrinking as it drys after construction is complete. This is a planning failure because less suitable green lumber was accepted for building design and construction.<\/p>\n\n\n\n
Reference<\/strong><\/p>\n\n\n\n (Eric E. Jorden, M.Sc., P.Eng. Consulting Professional Engineer, Forensic Engineer, Geotechnology Ltd., Halifax, Nova Scotia. ejorden@eastlink.ca<\/em>)<\/p>\n\n\n\n <\/p>\n\n\n\n <\/p>\n","protected":false},"excerpt":{"rendered":" I saw a catastrophic failure waiting to happen during a drive through New Brunswick a few days ago (September 26, 2020). A barn roof that was sagging a good 10 feet in the middle. For sure, a barn that was … Continue reading