NPS® Top Down system allows basement and rooftop spaces to be realised quickly without invading external areas, or requiring constraints at the site. It joins self-supporting characteristics and speed of NPS® execution with the need to realise basement and rooftop structures capable of absorbing horizontal stress, eliminating the need for structural accessory members that anchor walls, or supporting walls (tie-rods and struts).

The beam absolves strut function and the ceiling bearing member at the same time. NPS® Top Down allows the digging phase to happen at the same time as ceiling positioning operations.


  • The beam is both a strut and a definitive load-bearing element
  • Excavation containment
  • Construction site speed
  • Natively fire-resistant beams

Areas of use

  • Underground works in confined spaces and/or with existing perimeter buildings
  • Single span underground structures

Application-Technique Recommendations

The NPS® Top Down system is recommended when it is essential to limit the impact of building sites, i.e., in heavily infrastructured urban contexts and in historic town centres. 

Thanks to the high axial rigidity of the decks, deflection of the surrounding ground, subsidence and the risk of slipping of neighbouring buildings are avoided. 

It is well applicable, even in the case of large span decks, to counteract soil and water thrusts, and to limit critical points in the verification of buoyancy. Care must be taken when studying the slots that must be left in the roof for the movement of materials and for casting. 

Ing. Alessandra Favarato, NPS® Designer

Speed with definitive structures right away

  • The beams rest on the diaphragms and act as both struts and support beams.
  • With NPS®, definitive structures can be used immediately, avoiding the use of temporary struts.
  • NPS® elements are natively fire resistant, without the need for additional treatments.
  • Ground level is available shortly after the start of construction, as this is the first level to be completed. Then proceed in depth. Ideal for passable squares.

Less impact on the neighbourhood

  • The impact of the works on the neighbouring context is reduced thanks to the maximum rationalisation of the construction site areas.
  • No storage areas are needed for NPS® products,
  • The construction site is limited to its own perimeter, with no easement required.
  • Avoid the skyscraper syndrome. With Top-down, excavation takes place indoors, underground and not in sight.

Phase 0

Starting situation

Phase 1

Excavation and diaphragm laying. Beam laying level 0

Phase 2

Shoring and Beam Laying Level -1

Phase 3

Shoring and Beam Laying Level -2

Phase 4

Stripping and pouring of foundations

Phase 5

Laying of last beam level -2 and slab level -2

Phase 6

Laying of last beam level -1 and slab

Phase 7

Laying last beam level 0 and slab completion

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