Church Roof Collapse 1

[azcats]

This happened in my neighborhood. Came upon it just after it occurred. Fire alarm was activated and could hear sprinklers pouring water.

Appears the building was unoccupied. I'd seen no recent construction there.

Map Link

 

[Sym P. le]

The radio silence could indicate background issues. This roof is straight forward and the engineering is well understood. It shouldn't fall down under its own weight.

 

[Sym P. le]

... the roof collapsed from that beam down ...

From the video embedded in 12news.com article, Church in Chandler deals with collapsed roof just before Sunday services.

My take on the truss design was off as can be seen in the following screen grab from the above article. Note that the gable end trusses (double truss) are different from the typical roof truss, only a small portion of which remains.

With the above quote and close up images of the damaged beam top plate, it seems more likely that the edge condition of the top plate was not adequate to sustain the hanger load. In the image below, the upper portion shows the remaining top plate and mirrored broken edge piece aside each other and the lower portion shows a higher resolution of the broken piece.

It looks like the dark angled marks are nail marks from fastening the double top plates together. It would be unfortunate if a few nails and knots led to the plate splitting under load. I've wondered before if these hangar systems are equal to the task. It would only stand to reason that the plate edge condition requires scrutiny during installation.

*** Would this installation require 3" nails for the top flange hangar? It might be a significant error if 2" or shorter nails were used, making the double top plate irrelevant.