The brief
A new main staircase rising through three floors of a converted mill, landing on existing steelwork at each level. The stair had to work with the architect's layout, the lift shaft and the finished floor levels, including tiles.
What we did
- Modelled the stair in Tekla Structures, with general arrangement drawings - a 3D view, two plans and sections - issued for approval
- Took the design through five revisions as the design team commented: the going moved from 250 to 230 mm to match the architect's layout and the risers were regrouped
- Re-set the stair to the site-measured levels of the existing steel it lands on, raising three members by 15 to 18 mm, and offered two connection options where a landing beam meets a raised existing beam
- Built an interactive 3D model so the team could review the stair, check headroom and see every part in place
- Issued the full fabrication package "For Fabrication": 9 assemblies, 74 single-part drawings, a part list, a shipping list, and NC and DXF files for our machines
Details that mattered
- Rise and going. Every rise within a storey is equal, and the change between storeys is under 3 mm, so the stair feels even underfoot
- Headroom. We measured the headroom over the half landings in the model and flagged it to the design team before fabrication, as it sits close to the 2,000 mm minimum once finishes are added
- Fitting the existing building. The stair lands on existing steel at each floor, so we set it out to the site-measured levels rather than the original drawings
Timeline
- July 2026Tekla drawings issued for approval
- August 2026Revised to the architect's 230 mm going; design approved
- August 2026Interactive 3D model and IFC issued for review
- September 2026Revised to site-measured levels of the existing steel
- 17 September 2026Fabrication package issued "For Fabrication"