Berkeley Balcony Collapse - CSLB Action Against Contractor License

[wannabeSE]

There are two closed threads that discussed the apartment balcony collapse in Berkeley where 6 people died.

http://www.eng-tips.com/viewthread.cfm?qid=389528

http://www.eng-tips.com/viewthread.cfm?qid=389494

California's Contractors' State License Board (CSLB) has filed a complaint and may take action against the Contractor who built the apartments. The complaint includes information on how the contractor deviated from the plans. See

https://www2.cslb.ca.gov/OnlineServices/Accusations/N2015-483/N2015-483-20161129-Accusation.pdf

 

[allgoodnamestaken]

So the contractor basically did nothing to protect the cantilevered wood elements from moisture, and ignored all the requirements for waterproofing and water resistant materials.

Pretty tragic way for 6 people to die. I wonder if criminal action is to follow.

 

[gte447f]

I know this accusation is against the contractor, but I couldn't help noting that part of the basis for the accusation is that the contractor did not install pressure treated "micro-lam" joists as called for on the structural drawings. Well, I don't know if the situation was different in 2005, but currently Microlam LVL lumber manufactured by Weyerhauser (not sure if this is what was specified or what is referred to in the accusation as "micro-lam") cannot be pressure treated. This would amount to an error (inconsistency between the design model and reality) in the structural drawings/specifications. Granted, the contractor still would have had a duty to point this out to the EOR and get authorization for a substitute.

There are several other issues in the accusation that would be easy for a good lawyer to pick on. For example, the contractor used 3 layers of OSB decking instead of plywood as called for in the construction drawings/specs, but plywood, if not protected any better than the OSB, would not perform significantly better with regard to decay resistance, not to mention the decking was not the primary framing member failure that resulted in the collapse, it was the cantilevered joists.

One more thing, the accusation doesn't establish an actual date when the waterproofing subcontractor performed work on the decks in question, but automatically assumes the deck framing was completely unprotected from the time the decking was installed until the last date that the waterproofing subcontractor performed work 10 months later, during which time 38 inches of rain fell.

Not trying to defend the contractor, just pointing out that the net could easily be cast quite a bit wider... and I'm sure it will be if it hasn't been already.

 

[allgoodnamestaken]

> For example, the contractor used 3 layers of OSB decking instead of plywood as called for in the construction drawings/specs, but plywood, if not protected any better than the OSB, would not perform significantly better with regard to decay resistance, not to mention the decking was not the primary framing member failure that resulted in the collapse, it was the cantilevered joists.

Disagree. 3/4" pressure treated plywood is very moisture resistant. 3 sheets of OSB is nothing like it - OSB doesn't have water resistance similar to even regular plywood. Any time spent moist would turn it into a wood pulp paste.

 

[gte447f]

allgoodnamestaken,

The accusation doesn't mention pressure treated plywood, it only mentions plywood, and I said "if not protected any better than the OSB" then plywood would not perform significantly better than the OSB with regard to decay resistance... meaning after 8-10 years of exposure like that in the case of this apartment deck, plywood would also have been a crumbling mess.

Apparently, in this case, there was supposed to be a waterproofing membrane (HML 5000) applied over the deck, and that waterproofing membrane was omitted. I'm just saying that that omission played a lot bigger role than substituting OSB for plywood. But of course the contractor would have had a duty to get authorization for the substitution, something it presumably did not do.

 

[allgoodnamestaken]

My bad I read it wrong. I agree with you on.

 

[LionelHutz]

Did you wonder why they would use 3 layers of OSB or why the report covered it? One thought I had reading the report was that maybe the first layer or two was water damaged so they covered it with more indicating that they knew there was water damage happening.

 

[allgoodnamestaken]

I assumed they needed 3/4" thickness and had thin 1/4" OSB, so triples to get the same thickness.

 

[Lomarandil]

Residential isn't my area, I don't deal with waterproofing issues, and I've never used OSB -- but just from a bigger picture, 3x 1/4" OSB would be structurally inferior to 3/4" plywood, right?

I mean, unless I'm missing something substantial or the standard practice is to glue the heck out of them and develop shear flow.

 

[jayrod12]

You are quite correct. Significantly inferior.

 

[gte447f]

Actually, according to the accusation, the 3 layers of OSB consisted of 3/4" + 5/8" + 5/8" = 2", which is truly strange, but nothing surprises me when it comes to framers... I see things that defy logic in almost every building I go into. I don't know how they would have been able to get the proper thickness topping slab on the balconies with an extra 1-1/2" thickness of decking (i.e. the extra 2 layers of 5/8" OSB) that shouldn't have been there.

 

[LionelHutz]

So, people here not actually reading the report kind of like the contractors not reading the specifications????