Main Contractor: Skanska
Client: Helical Bar
Value: £3,100,000
Packages: Concrete
Architect: AHMM
Structural Engineer: Waterman

Structural alterations to strip the existing building back to its original frame, add three new floors and extending the floor plates.

The building is part of a larger scheme called The Bower development on Old Street roundabout and will bring 171,000 sqft (15,886 sqm) of offices and 7,300 sqft (678 sqm) of retail space to the Silicon roundabout area. The contract involves stripping back the existing building to its original frame, adding three new floors and extending the floor plates by about 15%. The building will be re-clad, with new washrooms and two extra lifts installed. The scheme is targeting the BREEAM Excellent environmental rating, using sustainable approaches throughout the refurbishment phase and installing water-efficient fixtures and fittings for building occupiers.

Works involve:
– Demolition to existing stair cores to form new services risers.
– Installation of cast iron drainage to the basement, including installation of the attenuation tank and connecting into an existing live sewer at the outfall.
– Installation of RC pile caps to transfer loads from the North/South slab extensions and the twin RC lift core.
– Installation of structural steels to newly formed riser openings.
– Formation of RC stair core and shear wall extensions to levels 16, 17 and 18 using the jumping formwork method.
– Installation of fair faced pre-cast concrete stairs with invisible connectors into the newly formed core extensions.
– Formation of the 18 floor (64m) twin RC lift core using the slipform method.
– Installation of the in-situ fair faced lift lobby slabs that span between the new slipformed lift cores and the existing building.
– Installation of RC slabs to the slab extensions on the North and South sides of the building.