The six people that died and seven who were seriously injured in the balcony collapse on an apartment building on Kittridge St in Berkeley CA never should have died or been injured. That’s my opinion, based on the information and documents I’ve received and photograph’s I’ve reviewed.
Eventually a jury or a mediator will award the dead and injured money to compensate them. Who will pay and how much they will pay will be the only question.
|Broken off joists from dryrot due to water intrusion.
Decks must be pre-sloped, then waterproofed.
From what my review and discussions with other experts have come up with, the wood cantilevered deck was framed out flat, despite the plans calling for a 2% slope on it. After being built, it was waterproofed using Grace 3000 bithuthene membrane, a peel and stick waterproofing sheet good.
|Grace 3000 waterproofing system on horizontal surfaces
requires the use of a sub-surface drainage membrane under the concrete
overburden to allow water to escape unimpeded.
|Waterproofing detail for deck shows Grace 3000 bituthene membrane
but the drawing FAILS to include Grace Hydroduct 660 Drainage Membrane.
We presume water WILL get under concrete overburden and will need a way
to drain sub-surface water out
After being waterproofed, it appears that sloping materials in the form of concrete backer board type materials were placed on top, then screwed down through the waterproofing membrane. Grace advertises that their membrane is “self healing” but also advises that any penetrations be patched. Near impossible to do in this type of situation. But someone probably thought hey it’s self sealing so no problem screwing through it.
Apparently no further waterproofing over the sloped materials was done.
Then a concrete deck was poured over this assembly. Water will leak through concrete. It’s permeable unless it’s waterproofed. Stucco was applied as the finish under the balcony. One design flaw with the stucco was that no vents were installed on the underside of the deck.
My theory is that water got through the concrete and in at the door area. The fasteners used to screw the concrete board down allowed water to penetrate to the waterproofing membrane. As screws rusted, they provided a channel for water to penetrate into the deck substrate and framing. Now with the wood wet, dryrot could begin.
|This pic clearly shows the joists of the deck in a rotted condition.|