Balcony Collapse in Berkley, CA 37

[MJB315]

See link:

http://www.latimes.com/local/lanow/la-me-berkeley-balcony-collapse-20150616-story.html#page=1

"We shape our buildings, thereafter they shape us." -WSC

 

[IRstuff]

24*60=1440, but that's for the deck, as designed, not as it was two days ago.

TTFN
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[moon161]

There was a real victim-blaming tone to the New York Times' story, Ew. As discussed, no way 13 people exceeded (100 PSF + margin) * FOS.

http://www.nytimes.com/2015/06/17/us/balcony-collapse-berkeley-dead.html?_r=0

'Muricans collapse balconies all the time, and no such tone. Perhaps the 1800's and NINA are still with us.

 

[3DDave]

Latest coverage is suggesting that the responsible building department evaluated them as 'decorative' balconies.

http://www.sfgate.com/bayarea/article/Berkeley-balcony-was-decorative-ex-member-of-6331841.php

I hope there are no decorative bridges or overpasses.

 

[Ron]

The photos imply wood rot. Whether this is conventional stucco, EIFS or one-coat stucco, it appears that the waterproofing was not done correctly. There are several groups in this area that have promoted for years that stucco is waterproof. That's absurd, but they have had the collective ear of the stucco applicators.

 

[Triangled]

Maybe 2x10s@12 with 4x10s each side?
Seems increasingly plainly a water issue...
The "decorative" concept is inconceivable to me. I've seen 'decorative balconies' in hotels with less than 12" cantilever and absolutely inaccessible by persons. But a double door with a 4' balcony absolutely invites the party outside. I assume everyone will crowd onto a balcony and lean over the rail to watch the sirens go by....

 

[Triangled]

Wondering if the water ponded on the balcony, poor drainage detail, non-ripped to slope joists ... not a lot of rain in California.

 

[rlflower]

Reading through the posts above - several very good posts, BTW - I see that no one chose to highlight what was likely the cause: lack of proper drainage of the balcony surface. Several of you cited lack of treatment of the joists (pressure treated), and some of you questioned proper use of the building code design live load. However, if the balcony had drainage properly installed and well maintained, then the serviceable life of the joists supporting the balcony would have been greatly enhanced.

The photo posted above does suggest lack of a proper drainage system. Rainwater was likely allowed to pond on the surface of the balcony, spreading over its surface. I think this is why we see fairly uniform deterioration of all of the joists; if there was localized deterioration, then I would have blamed a leaking drainage system.

To compound the situation, I question whether there was a proper moisture barrier in place that would have prevented - or at least limited - the amount of water infiltration into the joists.

Furthermore, one (or two) of you suggested that the header directly below should also be investigated for possible deterioration due to water infiltration. I agree that this possibility cannot be ruled out. This brings to light something about this type of problem that is so often overlooked: we need to open pandora's box, so to speak, and question the current state of all the other balconies in this structure. After all, the intent of the building code is life safety!

Richard L. Flower, P. E., LEED Green Associate
Senior Structural Engineer
Complere Engineering Group, Inc.

 

[LittleInch]

If you look closely at the balcony below there is what seems to be a small drainage hole with drain marks in the centre and the deck has a small upstand all the way round the edge. The destruction of the beams seems extensive and spread over all the beams. Maybe water entered the void under the decking and just created a moist humid atmosphere allowing fungus and rot to develop.

It could be something as simple as someone nailing on a top surface to the decking and puncturing the rather flimsy plastic sheeting that is evident.

Not building at least the main spars out of steel is simply a recipe for disaster. will be interesting if we ever see what the balcony under looks like once they've stripped off the deck.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[ssbatarseh]

I heard that in General 80% of litigations in buildings are due to water damage. This is a good example.

 

[jayrod12]

Ssbatrseh in wood buildings I would bet that number is significantly larger.

 

[manstrom]

I am not sure wet and corroded steel would behave differently than wet and rotted wood.

We build plenty of outdoor decks out of wood. I don't see many steel ones.

When I am working on a problem, I never think about beauty but when I have finished, if the solution is not beautiful, I know it is wrong.

-R. Buckminster Fuller

 

[IRstuff]

Most wood frame houses that have balconies, have wooden supports. In fact my old house had wood cantilever beams supporting a balcony just slightly wider than the one in question, that was about as deep.

TTFN
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[rlflower]

With loss of life involved, there could be a change in the building code. It is unfortunate that this is what it takes to motivate changes in the building code.

That being said, what do you think would be an appropriate code modification?

Richard L. Flower, P. E., LEED Green Associate
Senior Structural Engineer
Complere Engineering Group, Inc.

 

[boo1]

http://news.yahoo.com/6-killed-california-balcony-collapse-during-party-063649164.html#

 

[TehMightyEngineer]

That being said, what do you think would be an appropriate code modification?

All balconies or porches 4 feet or more above grade require all structural framing and connections to be moisture resistant (i.e. pressure treated wood and stainless or galvanized metal) and detailed to prevent moisture related failure (proper drainage).

Maine Professional and Structural Engineer.

http://www.fepc.us

 

[rlflower]

Quoting from the article you posted, boo1:

"Annual inspections are so important for all balconies and terraces, but particularly for ones made of wood," he said. "In fact, rotting wood is the biggest cause of balcony and terrace failures."

Are annual inspections required by the building code?

Richard L. Flower, P. E., LEED Green Associate
Senior Structural Engineer
Complere Engineering Group, Inc.

 

[rlflower]

Code reference, TehMightyEngineer?

Richard L. Flower, P. E., LEED Green Associate
Senior Structural Engineer
Complere Engineering Group, Inc.

 

[TehMightyEngineer]

rlflower: I was just making up an idea of what I would suggest for a code modification. I don't know of any code requirement that is similar to that, but it seemed like a low cost to value solution to this issue.

I don't know of any required annual inspections, I understood what he said as essentially "annual inspections are a good practice, especially for wood balconies".



Maine Professional and Structural Engineer.

http://www.fepc.us

 

[manstrom]

I think the failure was in being able to see the rotten wood. The balcony joists should have been PT out of good practice, but if they were completely sealed, then they wouldn't need to be PT. You can't mandate that all balconies be PT if it is completely enclosed by the building envelope; the (apparent) problem was that there was a hole in the envelope. Maybe add a code modification to allow projections to be easily inspectable or open bottomed.

Regardless, as a good practice these should always be PT, even if covered to avoid failures like this. Even if they are PT wood, my concern is what happens in 20 years when the PT is essentially gone and the wood needs to be replaced?

When I am working on a problem, I never think about beauty but when I have finished, if the solution is not beautiful, I know it is wrong.

-R. Buckminster Fuller

 

[Triangled]

...to my way of thinking, a code change is not the issue, at least on the design side. sure it'll make a politician feel good... now if a commercial balconied building owner was required to submit a sealed engineer's balcony inspection report every so often......