[Cob] [Greenbuilding] Building failures-Snow Loads

[SANCO Business Group, LLC]

Hi all,

Since we are pretty much snowed in here in New Mexico due to the recent and continuing snow storm, I took a 3 mile trip from my residence into Rio Rancho along NM Hwy 528 and observed 5 building failures due to the 15" snow fall we had.  I'm sure that in a city of 70,000 with 18,000 homes, there will be numerous structural failures within the city and throughout the state, especially in the rural areas.

Over and over we see posts on the list from people arguing that they have the right to build what they want, where the want, and can ignore building codes because the don't want to deal with the bureaucratic issues.  If we choose to ignore the building codes, at least let's use some common sense and apply tried and true structural and architectural principals.  Among these we should include:

  1-Span tables with a safety load factor
  2-Footing/column attachment
  3-Joist/Rafter/column attachment
  4-Ledger sizing and attachment

As noted earlier, 5 building failures were observed.  The failures fall into the following types

  1-Patio shed roof--undersized outer beam (span), broken in the center
  
  2-Stand alone detached car port-collapsed structure-added load from snow slide from upper roof.  Failure    was due to insufficient lateral support (knee bracing) between column and horizontal beams/rafters/joists (bridging)

  3- Attached add-on building-Failure in center of roof.  Failure caused by undersized (span) rafters

  4-Patio shed roof add-on.  complete failure/collapse.  The rafters pulled away from the wall ledger due to improper attachment to the ledger as a result of added snow load from upper roof that broke loose and added an additional horizontal load to the structure

  5- Stand alone structure-Failure in the center of the roof--cracked or broken rafters/ceiling joists.  Failure due to undersized members (span) to support the snow load

We have several Civil PE's on the list that can and should stress good building practices.  Why go through the expenditure of the labor effort and material expense to be the self-caused victim of a building failure.  It costs little or nothing in many instances to do it right and make it last with or without the building inspector.











SANCO Business Group
Paul Salas, Gen Mgr
PO Box 45741
Rio Rancho, NM  87174
(505)  238-0426
paul at sanco-bg.com
visit us http://www.sanco-bg.com

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