Key Takeaways
• Hidden lifts for New York landmarks must comply with ASME A18.1, which affects barrier types, gaps, gate positioning, and handrail requirements.
• Retracting stair designs require accurate pit depth and tread measurements, particularly when dealing with historic stoops.
• Westminster and Seattle configurations provide flexible options for ASME compliance, even in highly constrained or heritage-protected environments.
• Collaboration with accessibility authorities early in the design phase is critical for smooth approvals.
Introduction
A hidden platform lift is an accessibility system designed to remain concealed within a staircase or floor when not in use, preserving the architectural appearance of historic spaces. For New York landmark buildings, these lifts allow staircases and stoops to remain visually intact while still making entrances accessible to all visitors.
Designing and engineering such solutions requires careful alignment between architectural sensitivity and rigorous U.S. safety standards, particularly ASME A18.1. This article examines the technical considerations, compliance strategy and engineering detail involved in adapting hidden lift systems to protected U.S. buildings, based on real-world discussions and dimensional constraints encountered during feasibility meetings.
For broader context, see:
• New York Landmark Accessibility Lift → https://www.sesameaccess.com/knowledge-hub/new-york-landmark-accessibility-lift
• Lift Consultant Partnerships and Access Lift Companies → https://www.sesameaccess.com/knowledge-hub/lift-consultant-partnerships-access-lift-companies
Why New York Landmark Buildings Require Specialised Lift Engineering
New York’s accessibility regulators interpret ASME A18.1 with a strong emphasis on user safety and gate control. While UK and European lifts follow standards such as BS 6440, ASME mandates specific characteristics including:
• A solid upper landing gate rather than open-frame barriers
• Strict limits on maximum allowable gaps
• Required grab rails at defined heights
• Reduced distance between barriers and platform edges
These rules significantly influence product choice. For example, the rising barrier style used in some UK projects is not accepted by many ASME reviewers unless adapted. This is why the Westminster Lift and Seattle ADA Lift often form the baseline for U.S. compliance strategies.
For full reference, see ASME A18.1 → https://www.asme.org/codes-standards/find-codes-standards/a18-1-safety-standard-platform-lifts-stairway-chairlifts
Understanding Retracting Stair Pit Requirements
Many New York stoops include deep treads, multiple planes and protected stonework. When a lift relies on horizontally retracting stairs, the tread depth governs the pit length required for safe retraction.
Example from a real feasibility study:
• Six treads at 14 inches (355 mm) each
• Total run = 6 × 355 mm = 2,130 mm
• Required space for the stairs to horizontally retract into ≈ 1,486 mm (58.5 inches) after structural allowances
This calculation also defines where the top step riser must sit relative to structural beams or vaults beneath the stoop. Large treads often make architects reconsider whether a vertical-drop solution is better suited.
The phrase retracting stair pit length is important because it represents one of the most common search queries from architects tackling hidden lift projects.
The Westminster Lift: A Strong Match for ASME A18.1 Requirements
The Westminster Lift offers a robust rising barrier system that can be adapted to create a fully enclosed 1,100 mm protective zone around the platform. This helps satisfy ASME’s requirements for:
• Solid landing gates
• Controlled barrier movement
• Reduced gap tolerances
• Grab-rail integration
The Westminster system is often used when a project’s architectural conditions allow a reasonable retraction pit. Its design is well suited to heritage contexts and provides a proven pathway to approval in U.S. landmark settings.
Explore the Westminster Lift → https://www.sesameaccess.com/lifts/westminster-equality-act-lift
The Seattle ADA Lift: Ideal for Limited Pit Length or Handrail Constraints
Where space is restricted or handrails must remain visible, a vertical-drop configuration such as the Seattle ADA Lift may be required. Instead of storing treads horizontally, the stair modules descend vertically, greatly reducing pit length.
This configuration is especially effective when:
• Preservation rules limit stair rebuilding
• Handrails must rise and fall with the lift
• A solid upper landing gate must be integrated
• Long horizontal retraction pits are impractical
Seattle ADA Lift → https://www.sesameaccess.com/lifts/seattle-ada-lift
The Seattle configuration supports smooth approvals because it handles grab rails, barrier solidity and gate proximity more easily than horizontal systems.
Comparison Table: Westminster vs Seattle (ASME Adaptations)
| Feature | Westminster Lift | Seattle ADA Lift |
|---|---|---|
| Pit depth required | Longer pit required for retracting stairs | Minimal pit length due to vertical drop |
| Barrier type | Rising barriers with optional solid gate | Solid upper gate with rising handrails |
| Handrail flexibility | Usually fixed to staircase sides | Can rise/fall with lift for ASME compliance |
| Typical use cases | Stoop entrances with enough retraction distance | Highly constrained stoops or protected railings |
| Aesthetic integration | Mimics traditional steps when closed | Suitable where uniform tread depth is variable |
Working With Accessibility Authorities Early
ASME A18.1 approvals are influenced by the individual reviewers and the MOPD. The transcript describes how administrative changes can reset expectations, making early involvement essential.
The best practice is to:
• Share initial drawings and dimensional assumptions early
• Present both Westminster and Seattle configurations
• Discuss solid upper landing gate requirements
• Clarify any exceptions needed for baluster or railing details
• Document gate positions, barrier heights and clearances in section views
The Lift Consultant Partnerships page explains this collaborative method in more detail.
Design Recommendations for Architects
Define your tread module early
A variance of even 50 mm affects the retracting stair pit depth.
Reference exact measurements
For example, a 1,100 mm barrier height.
Use ASME terminology
Terms like solid upper landing gate, grab rail continuity and gap tolerance improve discoverability.
Model both product options
Most New York projects select between Westminster and Seattle based on geometry, preservation constraints and code interpretation.
Frequently Asked Questions (FAQ)
Can hidden lifts meet ASME A18.1?
Yes. When configured with solid barriers, compliant gates and correct grab-rail placement, both the Westminster and Seattle systems can meet ASME requirements.
Do stoop railings need to be replaced?
Sometimes new guardrails must be introduced to prevent falls when stairs retract. These can often be designed to rise and fall with the lift to meet ASME rules.
Is vertical drop better than retracting stairs?
It depends on pit depth and handrail conditions. Vertical-drop systems are often easier to approve when stoops contain deep treads or restricted structural zones.
What determines pit size?
Pit length is primarily governed by tread depth and the number of treads in the retracting staircase.
Will Sesame join meetings with U.S. consultants?
Yes, we frequently participate in multi-party technical reviews during early concept design.
Call to Action
To explore a feasibility package tailored to your building, book a meeting with a Project Manager at:
https://www.sesameaccess.com/book-a-meeting