Toronto Residential Home Collapse - Extensive Construction underway in basement

[CELinOttawa]

http://www.cbc.ca/news/canada/toron...lls-19-year-old-construction-worker-1.2760888

Terrible to see. What do you think the chances are there was a Structural Engineer involved?

 

[jayrod12]

Probably fairly high in the sense an engineer would have been contracted to do the foundation repair design and addition design. Then they would have put a note that says shoring to be designed and detailed by others. Then the contractor would've just done what always works everywhere else instead of hiring an engineer for the shoring design.

It's tragic. I've seen houses fully shored many times, I'm still always leery about going underneath.

 

[manstrom]

HGTV is behind this. That Housecrashers show is getting ridiculous.

 

[msquared48]

Seems strange for a wood structure to pancake like that. Must have lost central internal support from the foundation work - possible new basement excavation...?

Mike McCann, PE, SE (WA)

 

[CELinOttawa]

That was my first thought too Mike... It is also a 1920s building (or rather was) and those puppies are chocked full of load bearing walls. Even the roof is stick-framed onto the internal walls.

My money is on a basement renovation including increasing the height or extent of the basement.

 

[CELinOttawa]

Shoring is such a delicate art... Most of the time shores are fine or overkill for vertical imposed loads, but only very rarely (and exclusively on commercial or very high end residential jobs) have I seen proper cross bracing and stability of shores addressed.

Shoring should be simple. Shoring should be designed by an Engineer. Above all, shoring should be treated as serious and essential work.

 

[drawoh]

Lawrence, Avenue Road and Yonge Street is an upscale area of Toronto. Those homes would go in the high hundreds of thousands of Canadian dollars, at least.

My neighbourhood is infested with home handymen, including me, creating all sorts of possibilities.

--
JHG

 

[msquared48]

Don't let that word get out as the value of your ho9me will dr... Drat... too late.

Mike McCann, PE, SE (WA)

 

[rb1957]

i wouldn't be surprised if the hole in the ground isn't valued (not to say worth) 7 digits !

another day in paradise, or is paradise one day closer ?

 

[CELinOttawa]

Demolition is done... *sigh*

Someone died in this one gang; Let's try not to let this get too glib.

 

[TehMightyEngineer]

Maybe it's just me but if I died I would rather have people smiling than frowning. Of course nothing but respect for the worker and his or her family and friends, this is definitely a tragic reminder that gravity doesn't take a day off and that any construction can be serious business.

Maine EIT, Civil/Structural.

 

[rb1957]

apologies ... didn't mean any disrespect

another day in paradise, or is paradise one day closer ?

 

[CELinOttawa]

It's the (lack of) tone on the Internet. I was just thinking that a J-school grad could stumble upon this and get the wrong idea. Besides, while this discussion is likely to get some very serious thoughts out of the bunch of us, I haven't seen the subject that one (or a dozen) of us couldn't get sarcastic with.

I just pity the young fella in the hole. My father's team suffered a fatality on one of their projects when I was still in Uni. Young guy, two kids. He was told to get in the hole and dig, so he did. No shoring in that one; I wonder what will be found here.

I often think of that young man who was crushed on my father's staff's "watch" (no fault found on his team of staff, FYI) and of his kids. They'd be going to Uni themselves now, but would have lived in intervening years without their father in their lives, and that from a pretty young age.

 

[DamsInc]

My money is on a basement renovation including increasing the height or extent of the basement.

Yup. Underpinning of the foundation.

http://www.thestar.com/news/gta/201...d_19yearold_worker_involved_underpinning.html

 

[ajk1]

It is about 2 km from where I live. I may go take a look, but doubt that I would see much. This is the second house that has got into trouble in Toronto in the last couple of years, due to lowering the basement (if that was what they were doing), and perhaps the 3rd in the last few years. What is the responsibility of the building department?

I don't know if there was an engineer involved, but way too much structural renovation is done by non-engineers, which increases the possibility of tragedy, although engineers too can make mistakes. I have found the confidence of non-engineers breathtaking.

 

[Archie264]

>>>I have found the confidence of non-engineers breathtaking.<<<

Yep. As the saying goes, "fools rush in where angels fear to tread."

People who "know everything" can be extremely dangerous.

 

[moltenmetal]

The trouble with underpinning is the time and care it takes to do it right, which of course neither owner nor contractor want to pay for or wait for. The owner often doesn't know any better. The contractor wants to skip steps- excavate too much too quickly, doing it in fewer stages, they don't leave the right angle of repose, excavate under multiple walls at once without shoring etc., or go on to the next step before the concrete and grout have cured enough to be up to the job, because the rewards of taking those risks are pretty high in terms of saved schedule and money. They get away with it- most of the time, and that makes them think that the right way is excessively cautious. To do it right, they'd need to have three or four of them on the go at the same time, running back and forth between sites- tough to make money that way.

It's possible that the people involved were just plain incompetent, but the reality is they were probably just overconfident and in too much of a hurry. Obviously the risks are NOT worth it! Sad that it cost a worker his life.

I did 38' of underpinning on the long wall of my addition to my house, which isn't too many km away from the one that collapsed, though it's a fair bit down-market...I did the work myself because I had to be sure it was done right, as my family's safety and my investment were riding on it, given that this wall would become a central bearing wall of the combined house. I had both the city building inspector and the structural engineer I used on the project (who specializes in residential and who is also a personal friend) all over this work before I started, and my work was thoroughly inspected prior to each pour. The new combined house has been standing for eight years, I have had zero settlement issues, and as a bonus, the original wall now actually has a footing underneath it... The excavation gave me a chance to grout up a huge fault in the original wall which occurred because when this house was built in the '20s, they poured right against the cut earth of the excavation, and of course when dirt fell into the concrete they just kept a-pouring.

The native subsoil in my neighbourhood is a very dense clay till. A shovel just bounces off- 100% of the actual digging under the wall was done with a pick or a mattock- contractors use pneumatic clay spades which of course I was too cheap to rent. I lost 20 pounds digging those underpinning trenches, but regrettably I gained it all back...