Thread: Balcony Collapse Kills 6 in California

Six people were killed and seven seriously injured in the collapse of a fourth-floor balcony in Berkeley, California. Pictures show a structure that may have EIFS; the joists look like they just snapped off. Thirteen people may have exceeded its capacity as well.

http://www.nytimes.com/2015/06/17/us...eley-dead.html

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A lot of speculation will go on about the causes of the collapse, so I might as well start "speculating" now:

Something went wrong.

I viewed the video, slowed it down, and tried to capture the best resolution I could, but videos from news helicopters (which I speculate that is from) do not always produce the highest resolution videos, especially when doing a pause and screen capture.

That said, I can see what I speculate to be a waterproof membrane draped from under the door down over where the balcony was, and it does not look wide enough to cover the entire balcony (although the edges could have torn off) nor does it look like it has been secured in place to the balcony subfloor.

Looking at the doors, they are possibly 3 ft door, for 6 feet across, with possibly 2 ft or more to each side, for 2 ft + 6 ft + 2 ft = 10 ft wide, by what I speculate to be possibly 5-6 ft deep, which would make the balcony 50-60 sq ft.

At 40 lbs square foot live load design, possibly even greater, that would work out to just about the number of people (average weight of 200 pounds) as was on the balcony.

That is, if properly designed, properly constructed, and properly maintained ... which is a lot of "properly" presumptions to make.

I am not putting aside or making light of the deaths of the 6 or 7 who died, or the 6 or 7 who were injured, those are real - I am just speculating on possibilities of the balcony and what happened.

If the balconies are like the many that I have seen, their construction leaves a lot to be desired as few - if any - match the approved documents/drawings/plans/notes/specifications.

Just some initial speculation to start off with.

Some construction consultant and/or engineer will need to get up close and personal with what remains, and with the debris, to compare as best possible what was there to what was supposed to be there.

Then, they should do some investigating into other similar balconies on that building to document how they were constructed.

Additionally, have these been through an earthquake before? If so, how could that have affected the structural strength of the balconies?

The live load for a balcony is 60 psf, and a news report indicated that 60 psf is the local requirement, and that the balcony is 5x10. So, the balcony should not have been overloaded, but it may have had the most load it ever had.

My guess as well was problems with the flashing causing deterioration or corrosion of fasteners. I would hope they used PT wood, but if the balcony had a water-proof membrane, maybe they did not. I imagine a leak in a balcony could go undetected for a long time, especially in rental units.

In reality, 2007 cheap cheap construction-probably way more than one thing wrong.

Originally Posted by Mark Reinmiller

The live load for a balcony is 60 psf, and a news report indicated that 60 psf is the local requirement, and that the balcony is 5x10. So, the balcony should not have been overloaded, but it may have had the most load it ever had.

I was trying to remain on the conservative side of the limits, looks like I was. Good.

I would hope they used PT wood, but if the balcony had a water-proof membrane, maybe they did not. I imagine a leak in a balcony could go undetected for a long time, especially in rental units.

In reality, 2007 cheap cheap construction-probably way more than one thing wrong.

Agreed with the probable lack of quality or any semblance to quality in the construction.

I have seen many waterproofing membranes mechanically fastened down to the substrate (typically plywood or OSB) when it is specified to be fully adhered. Each mechanical fastener then becomes a "leak".

I don't recall ever having seen PT used for trusses in a location such as that - they try to waterproof it with membrane, sometimes built-up mopped on liquid applied, but usually (for small areas like balconies) a sheet of waterproofing laid out over it. Way too many ways for that to be done wrong and create paths for entry of water when done that way.

Around here we do not have a lot of mid-rise construction. Two or three story condos would more likely have PT wood balconies with PT or Trex decking. Mid-rise buildings, which are often older apartments often have reinforced concrete balconies, which have their own problems. Sometimes I see balconies or roof decks with fiberglass roofing. I agree that if the intention is to have a waterproof membrane on the balcony than it is not likely that they would use PT wood.

Whoever screwed up has probably gone out of business or reincorporated. I think the building it owner by a REIT or large corporation, probably with good insurance or deep pockets, so they will probably pay big-time (but only after the lawyers fight it out for years).

Originally Posted by Mark Reinmiller

... probably with good insurance or deep pockets, so they will probably pay big-time (but only after the lawyers fight it out for years).

Agreed

This video has some good close-ups of the joists. Looks like some serious water staining and wood rot. Watch the part where the workers were pulling the membrane away. Lots of rotting wood falling away.

http://news.yahoo.com/6-killed-calif...63649164.html#

Don't know how long the video will be available.

Since I have not personally examined the failure; my thoughts are no more than conjecture.

I see (think I see) EIFS on a balcony bottom (and building). 1. EIFS should not be installed horizontally. This is a common error that I come across frequently. 2. Although I may see a drip edge cap; I cannot determine if there is a drainage membrane present (or failed) to protect what may be a plywood deck.

Since the beams broke so evenly, and not immediately against the building, where leverage would expect to have caused the break, I wonder if there was a leaking seam in the (plywood?) decking above the break(s) locatiion.

What I conject I see is what I call a "Hot Box", with no drainage or ventilation. Whatever moisture enters can fester and wreak havoc. At the very least, I sometimes recommend installing vents and drains in a box like this.

EIFS is generally light weight, but when horizontal and saturated can be quite heavy.

I am currently involved with a site (5 story condo), that had horizontal EIFS on the balcony bottoms. One bottom fell (EIFS only-remaining structure is steel and masonry), and they had to remove the bottoms of the remaining balconies.

Likely, every balcony is "flashed" in a similar manner:

balcony-02 635700819347204378-AP-Berkeley-Balcony-Collapse.jpg

balcony-02 berkeley-balcony-collapse.jpg

balcony-03 8077837_G.jpg

Those are great pictures, where did you get them? Are there more?

Originally Posted by Steven Turetsky

Those are great pictures, where did you get them? Are there more?

GOOGLE "Berkley Porch Collapse", select images.

Those are the clearest, though, and none are high enough resolution to usefully enlarge.

- - - Updated - - -

Originally Posted by Steven Turetsky

Those are great pictures, where did you get them? Are there more?

GOOGLE "Berkley Porch Collapse", select images.

Those are the clearest, though, and none are high enough resolution to usefully enlarge.

- - - Updated - - -

Originally Posted by Steven Turetsky

Those are great pictures, where did you get them? Are there more?

GOOGLE "Berkley Porch Collapse", select images.

Those are the clearest, though, and none are high enough resolution to usefully enlarge.