The design competition entry proposes a staircase called "Minuscule" for 240 Blackfriars Stair that is inspired by Ramboll's Scandinavian design principles. The staircase aims to promote interaction between people, incorporate sustainable materials, and showcase Ramboll's expertise in sustainable energy. It consists of a timber space frame with a precast concrete structure that spans between floors and features a split-level design with a floating central stair section. Load calculations and modeling were done to ensure compliance with building regulations.

1. 240 BLACKFRIARS STAIR DESIGN COMPETITION
Matthew Powell – Ramboll, Leeds
“Minuscule”
An idea inspired by Ramboll’s Scandinavian vowel
Objectives… Create an idea, which:
 Would look out of place if it wasn’t in a Ramboll office.
 Avoids causing a “bottleneck”. Wide enough for 2 to pass, avoid an inefficient spiral
design, distribute pedestrian traffic efficiently, land and depart on same side.
 Is enhanced by people moving around it. Split levels, promotes interaction between
people, encourage visitors to take a detour to see how it works!
 Promotes us as a “Sustainable Energy Consultant”. Incorporate sustainable materials
such as timber, precast concrete, wind turbine space frame.
 Uses our contacts in industry. Laing O’Rourke Steetley Precast Plant.
The Approach The Minuscule Climbing the Accent
Inspiration
Channel 4 Television Idents Falling Water, F.L. Wright Ramboll Logo’s Minuscule
Main Materials
Timber Space Frame Clear Balustrade Precast Stair Sections
The drawings’ visual details how polyvinylchloride is proposed for the magenta corporate
cladding, and either steel decking or precast planks may be employed for the short
hanging steps section.
Load Path Explanation of Diagram in Drawings Section
Precast concrete beams span east to west and are simply supported at the structural
slab level at third floor. The existing slab can be checked for punching shear, and if

2. required Fibre Reinforced Polymer Reinforcements can strength the soffit of the slab.
These will be concealed from view within the clear zone (services and ceiling).
Fibre Reinforced Polymer:
External Reinforcement to Existing Slab
Falling Water Stairs: Two hangers at each step to
prevent twisting
The 2 beams are split into two sections with a joint running parallel to the stairs. This is
to facilitate a dowel joint between the precast beam support and the stair section.
Bearing ends of the beams can be incorporated into the office environment at one end
by balustrades and the other by the seating area. The central stair section is them
floating above the second floor to create the accent of the Scandinavian vowel. Lower
sections rest on the second floor slab which can be checked for punching shear and
allowable additional loads. The timber space frame is for visual effect.
Stability
The maximum void of 4500 x 4550 minus 100mm clear zone was utilised to create a
clearer visual connection between floors. The border of the void is braced by structural
hollow sections creating a box resisting longitudinal forces. Two precast beam sections
transfer the load from the hanging section into the third floor slab.
Modelling Loads Required Rebar Check Pattern Loading
Compliance with Building Regulations
Incorporating a landing required meeting a few regulations. The landing is wider than
the maximum internal width of the staircase. The finished floor level is 2 meters below
the minimum ceiling height as required. Generous going and risers for assembly building
level have been incorporated where 15 steps is the maximum run between landings.
Factors such as required overlap, the 100mm sphere rule, and minimum clearances have
been checked by modelling in 3D, and then incorporated into the proposed design.
Maintenance/Demotion
Individual component sizes are below 3 meters in length for delivery to site. Sections can
be reduced in size or cast in-situ if access is a problem. Connections are not concealed in
order to be inspected and maintained. Design can be remodelled for a future tenant.
Materials such as concrete, glass and steel can be recycled.