Safe demolition in the heart of a city is a challenge for the supply chain.
Scaffolding operations play a critical role in protecting the general public and neighbouring buildings as well as ensuring demolition activities can progress safely.
Demolition, even when controlled well, has significant risk that can be mitigated through safe use of scaffolding.
Safe use of ties
Although the building will be getting demolished, it is crucial that the structure remains stable throughout the demolition. This is achieved by the building being braced and tied.
This allows us to safely tie to the columns of the building, strengthening the standards and allowing them to hold the weight of the structure and any imposed loads.
Our in-house design team provide designs for the proposed loads to the columns. Working with the demolition contractor’s structural engineer allows us to ensure that these reinforced concrete columns will be able to take the imposed loads.
This ensures that despite the vibrations from the demolition works, the ties maintain structural integrity and are unaffected. As each level is struck, the ties are removed following the progressive dismantle of the building.
Physical ties are often favoured as they are tied through an exposed area and supported by the scaffold structure, rather than mechanical ties which are drilled in.
A mixture of ties can also be used, as we did at East Croydon Post Office for Cantillon. We began by using mechanical ties. Because there was no exposed opening within the façade to allow us to tie through using physical ties.
As the demolition progressed, openings within the façade were created, allowing for physical ties to be added in.
As the demolition progressed and a slab was struck, we installed a new tie to the slab below.
Protecting from dust and debris
As a result of demolition works, there is a significant amount of dust and debris produced. This needs to be contained to protect the public and the neighbouring buildings.
In order to prevent this our scaffold is used to act as a screen.
A key example was the works carried out at 1 + 2 Broadgate, where the demolition was part of the 10 year redevelopment of the Broadgate area.
The purpose of our scaffold on this specific project was to provide protection rather than access.
Working with Cantillon, we provided a full external scaffold to the existing building as a screen to ensure all debris remained inside, encasing the dust created.
Avoiding overloaded scaffolds
When demolishing a building, the most common method is working inside and pulling the building inwards.
This often leads to lifts becoming overloaded and damaging the scaffold.
To alleviate this risk, we ensure clear and direct communication with our clients at all stages of the project.
Clarifying and communicating the load class of the scaffold is vital in ensuring that the scaffold doesn’t become overloaded when in use. Overloaded scaffolds can contribute to building and scaffold collapse.
Protecting the general public
When working within some of the busiest areas of the capital, protecting the public is paramount when large exclusion zones are not possible.
Protection gantries provide safe access to the general public around the site ensuring they are unaffected by the high risks works behind the scaffold.
Enabling waste disposal
There is a significant amount of waste to dispose of during demolition projects.
For efficiency, access bridges are built to enable waste to easily be removed from high level buildings.
This method is commonly used on many projects, including our work at 120 Fleet Street for Erith.
Working in a multi-level building meant that waste needed to be removed from high levels, so low level access bridges were built. These bridges create a clear access area for machine to remove the debris from the drop zone.
The drop zone is created within the building by either using existing lift shafts, creating voids through floor slabs or utilising natural voids like the atrium. Machines can then enter the site and easily access the waste from the drop zone and dispose of it.
Ensuring the right capabilities
High risk works require experience and the right capabilities, from planning and design through to execution.
Using the right scaffold contractor on a demolition project can ensure efficiencies but also protect workers and the public from the impact of demolition operations.