In this enquiry, a design team for a Grade II listed luxury store entrance explored how to convert a short flight of external steps into a fully hidden, staff‑managed platform lift—maintaining the building’s character while unlocking independent access. The conversation focused on fit, safety, heritage sensitivity, and a clear next‑step plan to de‑risk the project.
The entrance sits on a busy city pavement, with basement accommodation directly below. The team sought a “beautiful, seamless stair that turns into a platform lift”—no bullnose overhangs, no visual clutter—while satisfying:
- Listed-building constraints and a preference for minimal visual impact.
- A relatively modest rise (~616 mm) that still introduces fall risks and public-realm considerations.
- The need to preserve (or sympathetically re-make) granite treads/risers and handrail character.
- Space limitations below the upper landing (basement toilets/services), influencing pit length/depth.
- Public operation risks at a high-footfall entrance, demanding strong safety interlocks and supervision.
Sesame engineers walked the team through two core mechanisms—each proven on heritage sites—and the operational model that keeps the public safe:
- Mechanism options:
- Mayfair (horizontal retracting stairs + hidden rising barrier at the upper landing): Shallowest build-up; with ~800 mm stair retraction below the upper landing plus the ~616 mm rise, the total vertical allowance is ~1,400 mm (subject to final detailing). Pit length behind the top step depends on tread count; with 3×300 mm treads, the retraction length can be ~900 mm. This option is also the most visually "invisible"—no "stud" access points on treads.
- Buckingham (vertical-dropping stairs): Requires greater pit depth below the lower landing but reduces space demands behind the top step—useful if services constrain horizontal retraction. Compatible with an upper-landing rising barrier (typically ~1.6 m pit depth below the upper landing for the barrier module).
- Upper-landing protection (public safety): The preferred solution is a hidden rising barrier at the upper landing that appears only during lift travel—minimal visual impact and robust public protection for voids greater than 500 mm. An always-visible swing gate reduces pit impact but is less preferred visually. A rope barrier with keyed interlock can work in managed, low-traffic settings but isn’t recommended here.
- Operation & compliance: The Mayfair or Buckingham with wrap-around tow-guard is a wheelchair (seated-user) lift under post-2011 rules; standing travel isn’t permitted. In busy public environments, Sesame configures the system "off" between uses to prevent misuse; a "call for assistance" triggers staff attendance. Staff-managed operation aligns with the site’s doorman/facilities protocols and de-risks movement among unaware pedestrians.
- Layout optimisation & handrail strategy: A 1,500 mm turning circle may share part of the platform footprint once deployed—an approach often accepted to centralise the handrail and ease clearances. Crush hazards near the right-hand handrail can be mitigated by shifting the stair/lift ~300 mm away, adding a safety edge along that flank (less robust in a high-heel/high-traffic environment unless reinforced), or detailing the handrail so the horizontal member stays clear of the rising tow-guard envelope. With the ~616 mm rise and the handrail set as high as practicable, the tow-guard won’t pass the handrail’s horizontal member, avoiding crush risk while preserving aesthetics.
- Materials & heritage finish: The proposal includes granite treads, risers, and landing (target ~20 mm tile thickness, subject to on-site verification) and a stainless-steel skirt (initially) for the Mayfair configuration. Final trim interfaces will be tuned in site-specific drawings to blend with heritage detailing.
After the session, the team agreed to:
- Send PDFs and DWGs to Sesame.
- Sesame will test both mechanisms in plan and section, move the assembly left to centralise the handrail, verify pit length/depth (considering ~900 mm retraction for three treads), and map clash risks with basement services.
- Sesame will issue a budget based on the most straightforward, lowest-impact option (likely the Mayfair with hidden rising barrier). If accepted, they will carry out a site survey and produce site-specific drawings (no charge for this design iteration).
- If later surveys show scope to shave pit requirements, Sesame has next-generation rising-barrier technology in development that may reduce the ~1.6 m envelope by the time this project mobilises.
By combining hidden-in-plain-sight engineering, staff-managed safety and thoughtful handrail/turning-space geometry, this project shows that heritage character and modern accessibility can co-exist. The entrance remains a luxury design statement while welcoming every customer with dignity. It’s a model for listed retail frontages, embassy steps and flagship venues facing similar constraints.
Q1. Which mechanism best fits a shallow rise with basement constraints?
A. The Mayfair (horizontal retracting) typically wins on overall depth when basement space is tight behind the top riser, especially with 3×300 mm treads (~900 mm retraction). We’ll still test the Buckingham if vertical drop helps your specific clashes.
Q2. How do we protect the public at the upper landing without visible gates?
A. A hidden rising barrier is the preferred solution here: minimal visual impact, compliant protection over voids >500 mm, and proven on heritage sites.
Q3. Can visitors operate it themselves?
A. In high-footfall settings we configure a staff-managed mode with call-for-assistance. It prevents misuse, aligns with doorman/FM routines, and upholds post-2011 seated-user rules.
Q4. Will the handrail create a crush hazard?
A. Not with careful detailing. With a ~616 mm rise and the handrail’s horizontal member set appropriately, the tow-guard won’t pass the rail. Alternative mitigations include 300 mm set-back or a reinforced safety edge if needed.
Q5. What finishes are typical for a listed context?
A. Granite for treads/risers/landing (c. 20 mm tile thickness, TBC), and a stainless-steel skirt around the mechanism—both tuned in site-specific drawings to match the heritage palette.