Demolitions and cutting on construction projects

​Sometimes construction projects involve demolition of existing structures. On occasion clients change their minds after a structure has been built and they require the newly completed structure demolished, or a hole cut in it. Regrettably, on occasion contractors make mistakes, or work is of a poor quality, so a completed structure must be broken down. Demolition work is often dangerous and must be done with care.

Some examples of demolition accidents
https://www.abc.net.au/news/2019-09-04/sydney-booty-parlour-gym-destroyed-by-mistake/11476874
https://www.constructionenquirer.com/2020/01/15/worker-killed-as-excavator-falls-through-concrete-slab/
https://www.amny.com/editorial/two-workers-seriously-injured-when-wall-collapse-drags-down-scaffolding-during-harlem-demolition/

Cutting and demolishing safely on your construction project

Before demolitions starts, all hazardous materials must be identified and removed separately, where required demolition permits must be in place, electrical, gas and water supplies must be cut-off to the structures and the lines made safe, all salvageable material should be removed, safety steps must be in place to prevent injuries to workers and the public, exclusion zones must be clearly marked and enforced so that falling debris don’t injure people or damage property, steps must be implemented to minimise dust, areas to be demolished or removed must be clearly marked so that there’s no confusion or risk of the wrong structure being demolished, the right equipment must be used (equipment that’s too big may result in excessive vibrations or loads damaging other structures) and rubble should not be allowed to accumulate where it could block access or cause overloading to structures.
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But, even on a normal construction site, often contractors have to cut or drill holes through walls and concrete slabs to make way for pipes and utilities. Cutting a wall brace could make the whole structure unstable, and it could collapse when there’s a strong wind or an external load is imposed on the structure. It’s hard to think that cutting one brace (sometimes only a few inches thick) could cause a whole steel structure to collapse, but unfortunately it has happened. Similarly, care must be taken when cutting holes in a concrete floor slab. Cutting through vital reinforcing could weaken the slab causing it to sag and crack. Some concrete slabs have tensioned cables and cutting one or more of these can lead to a serious failure. Therefore, always take care when cutting structures, in fact check with the design engineer that the hole can safely be cut there. Always check first before cutting.

Conclusion

Cutting and demolishing structures can be dangerous. Always thoroughly understand the risks and make sure the team takes the appropriate safety measures. Where necessary have an engineer check the structure before cutting or demolition works start. Always check that you are cutting in the right place - you wouldn't want to cut an opening in the wrong place, or demolish the wrong structure.

Other useful articles
Expect the unexpected in construction 
Damaging existing services
Managing subcontractors on your construction project. What you should consider.

​This article is an extract from the book 'The Successful Construction Supervisor and Foreman'.
​© 2021 This article is not to be reproduced for commercial purposes without written permission from the author.

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