Case Study // Walmar House – Great Portland Estates

Erith was employed by Great Portland Estates to carry out the demolition of Walmar House in Regent Street, London.

Walmar House was built between 1910 and 1925 and had a steel frame with hollow pot ­floor, a mansard roof and a single level basement.

Scope of Works

The brief was to demolish a section of the later built rear structure and roof of the building which faces Regent Street. Additionally, there was a requirement to remove the structure from behind the façade of the connecting building on Great Castle Street.

Extensive temporary works were designed by our in house team to maintain the stability of the buildings during and after demolition. This comprised of bracings and dead shores to maintain the lateral stability of the frame and a façade retention scheme to Great Castle Street elevation. The façade retention that was devised comprised horizontal trusses to the external, built into the scaffolding which was in turn designed to support the vertical loads imposed. This option meant that the interior of the building was clear of obstructions for the new build.

Innovation

Underpinning, drainage and reinforced concrete works were carried out in the basement during the demolition – made possible by placing a tower crane on to the roof of the building, attached to the central stair core columns with minimal additional stiffening required. This innovation meant that early demolition of the low level roof to the rear would then provide access into the basement during the demolition works. In turn the new core could be started 12 weeks earlier.

Project Goals

  • Works completed 12 weeks ahead of contract programme
  • No reportable accidents or incidents recorded throughout the life of the contract
  • Project completed within the desired contract budget