how to collapse your house

creeper

http://toronto.ctv.ca/

rossfingal

Oops!
Major - "faux-pas""

Yoyizit

So the basement floor provided rigidity for the basement walls. Maybe on other jobs that didn't collapse they were just lucky.

gma2rjc

I'm glad the 3 workers made it out alive.

This wouldn't have happened if Mike Holmes was on the job.... j/k

__________________
"The problem with quotes on the Internet is that it is often difficult to verify their authenticity." - Abraham Lincoln
The economy is so bad, Exxon-Mobil laid-off 25 congressmen --- Maxine

concretemasonry

It sounded like an underpinning to lower a basement floor that did not go right or as expected. The first floor slab provided a laterial "diaphragm" that kep the tops of the walls far enough apart, but the lateral force on the walls could have caused an unexpected failure that ultimately dropped much of the structure and cause the above grade structure to fail completely because of a lack of rigidity and support where it was designed for.

Just an example of to use someone with knowledge for an underpinning.- Not an amateur or DIY project since anything can happen until the job is done correctly and secured.

Yoyizit

And if the soil was saturated from previous rains there might have been a lot of pressure on those walls, more at the bottom.

concretemasonry

Yoyzit -

Obviously, there would be more lateral soil pressure deeper, so the basement slab resisted the lateral pressure as required for both block and concrete walls systems, so the walls failed and everything came down. Many codes require 3 1/2" of contact between the wall and the slab, since rebars/dowels are not always that positive or really there.

Very often, a good contractor will leave a 12" wide section of floor every 4' to provide lateral support during construction of something as seemingly unimportant as a interior drain tile installation at the level of the bottom of a footing.

Dick