Lightweight structural concrete for hotel rooftop extension

Shoreditch, London



Nationwide Concreting Limited



Location type



June 2019

The challenge

To construct a roof top extension on top of the luxury hotel NOBU in Shoreditch. The plan was to add an additional 1 storey of hotel rooms, suites, dining areas and open terraces that would replace the existing planted roof.

Our solution

To supply Tarmac Toplight C lightweight structural concrete in a pump mix with the addition of steel fibres, ensuring maximum weight loss of 35% with no compromise on structural concrete performance.

Results and benefits

The lightweight concrete mix design LC30/33 D1.8 with a density of1600-1800kg/m3, containing structural lightweight aggregates was pumped 40 metres vertically on to the new composite deck floor. By adding steel fibres into the lightweight mix the composite metal deck system could be installed without the need for traditional expensive and slow steel reinforcement across the deck. The use of lightweight concrete, furthermore, reduced the load by 35% which meant the existing structure did not need to be reinforced or under pinned. The construction programme time was also reduced considerably which insured completion of the work was done in the shortest time possible and NOBU hotel could quickly resume business as normal.

Learn more about TOPLIGHT C
Download case study

Additional info

Toplight C can be used in any application where normal weight concrete is specified as follows:

To create lighter concrete slabs, foundations, floors and walls to reduce loads on structures.

For reinforced concrete slabs

Using Toplight C, Designers can not only look to reduce the thickness of the slab, columns and foundations but also reduce the amount of steel mesh required resulting in a quicker more cost-effective greener building

On composite metal decking

Toplight C is ideal for composite metal decking. As spans increase the deflection becomes the defining factor. The use of Toplight C minimises the weight by up to 30% therefore reducing the deflection.

Lightweight structural concrete for hotel rooftop extension contact

TOPLIGHT C case studies