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Re: Berkeley balcony collapse

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Chuck,
Agree with all of your comments. It is not likely one mistake but a
combination of errors. Every step of the process must be tightened up, and
the best detail in the world on paper is useless if it is not installed
correctly. Reminds me of many of the conclusions from Hurricane Andrew's
devastation were that yes, the codes need to be improved, but the biggest
issue was compliance and inspection.

 Even if it is one problem, then water testing as they described it would
only show the balcony slopes away and probably drains just fine. The pics
show the lower balcony slopes quite a bit, at least visually it looked that
way. We can conclude it was not a singular pin hole leak or slash in the
membrane, because every single joist was badly rot-damaged. This leads me
to think the wall-floor flashing was the main culprit, though it could have
been the membrane because we did not see the entire joists just the broken
off ends (and like Chuck this seems to me to be the least likely). And good
luck finding that on a finished building.

A common error I see on roofs and walls when it comes to waterproofing is
relying on sealants (caulk, roofing cement) where mechanical flashing is
necessary for long-term durability and reliability. So you could seal up a
balcony even with high grade sealant, and water test it and get a pass.
Then as the building ages and you get creep and expansion/contraction,
aging of the sealant, etc, slight gaps open up and then you start getting
water infiltration.

This paragraph is confusing, but probably the journalist needed a
structural engineer to proofread it:

*She said pictures clearly indicate dry rot led to the collapse. Had it
been overloading, the wooden joists would have broken flush with the wall
of the main building, but instead they stick out slightly with dulled
edges, with mold showing. She also noticed the water-stained protective
membrane, indicating water infiltration.*

I'm not blaming Lisa, as she may not have even said this, but there is no
such thing as dry rot. Fungi must have a source of moisture to live. I
believe this misnomer got started when people discovered rot damage in dry
wood, which only means the moisture source is gone and the wood dries out,
so it is older rot damage and the fungi may be inactive.

Also, the joists could have broken flush with the main building wall, which
is the point of highest bending stress, but water travels in weird ways and
decay isn't that precise. But it is pretty clear it was rot damage as many
of us thought that right away.

I like architecture and architects and have many as close friends. But some
blame has to be thrown the way of the architectural community here, and it
is something I see a lot, which is form vs function. You have to have a
balance. I inspect leaky roofs all of the time where the designer (probably
not even an architect) on a custom house thought that 30 dormers, hips and
gables equals good residential architecture. What you end up with is roofs
draining towards walls, valleys everywhere, near flat portions of roof,etc,
all of which were nearly impossible to build and weatherproof correctly and
are destined to fail. My own house has a couple spots like this. Some very
famous architects have been blamed for this very thing when their iconic
buildings start leaking because all they were focused on was form and
aesthetics.

Imagine had you put a little cantilevered roof over this balcony, even just
a couple of feet out, to shed water off the wall and also provide a little
shade? Very little extra cost and you could do a low profile design that
would look nice. We may not be having this discussion...

Thanks for sharing again Hassan and your thoughts Chuck.

Andrew Kester, PE
Florida

On Sun, Jun 21, 2015 at 3:24 PM, Chuck Utzman <chuckutzman(--nospam--at)gmail.com> wrote: 


> Hassan-
> Keep up the good work. A couple of comments:
> The leak(s) here could have been from several sources: deck to wall, door
> pan, door to wall flashing, the door itself, and least likely the deck
> membrane.
> Deck flood testing is usually awkward, and while it might reveal a gross
> error, often these leaks develop over time and would not be present
> immediately.
> Usually the architectural details are very inadequate, but even the best
> details don't help much without thorough inspection during construction.
> Typically the workers don't understand or follow the waterproofing details. 
> Insuring compliance requires multiple inspections and City doesn't look 
> at anything other than the roof..
> However, the perfect need not be the enemy of the good. At present, the
> Code & inspections are abysmally inadequate and any additional requirements 
> would be a big improvement. If this ever gets to the point of public
> hearings (which it should) you might check with the folks at Westcon.
> http://westcon.org/ These guys specialize in construction defect problems
> and a number of them are headquartered in the east bay.
> Chuck Utzman, PE

Truncated 565 characters in the previous message to save energy.

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