On a personal note from the director of Subterranean Spaces:
You may have read recently about the property falling down in Chelsea. This was a property being worked on with an on-site main basement contractor.
Basement construction is a specialist area and requires many years of experience to perfect it. What people do not see and must know about, is the term “temporary works”. A professional company will highlight this cost in their quote.
Temporary works generally means works that are normally unseen and, in particular, these works involve temporary propping and support work, which would be holding up load bearing structures like walls, floors, beams, foundations and all structures in order for construction works be carried out.
It is very important for clients to identify this item. Normally, the temporary works will be designed by a structural engineer and would be linked to the structural design of the basement works. In most cases, this is incorporated in the party wall award and will be built in to that award.
In addition to this, it is important that the main contractor or basement builder has the right tools for the job. Supporting structures is not light work and requires, in many cases, heavy props which sometimes require their own temporary foundation to take the loads and the weight. This process is again designed by a structural engineer or sometimes the suppliers of the props.
An experienced basement builder knows, at a glance, what needs to be supported. They would also know how to stop any structures slipping. It is important to brace works that are completed as until the ground slab has been poured, nothing is safe unless temporary works are in place.
So remember to look deeper into the meaning of “temporary works” and where it is maybe highlighted in your quote before you instruct a company and check insurances.