## Lift Pit Drainage and Installation Coordination
### Key Takeaways
- Correct sump pit and conduit placement are critical for long-term lift reliability.
- Early coordination between site teams and Sesame engineers prevents costly rework.
- The Top Step Riser (SCSR) reference ensures uniform pit geometry and installation precision.
### Introduction
When installing a concealed or short-rise accessibility lift, drainage coordination is one of the most crucial yet easily overlooked details. A well-designed pit layout ensures that the hydraulic system, conduits, and sump pit all function seamlessly without obstructing the lift frame.
This article, based on real project coordination between Sesame engineers and site contractors, explains how to design, position, and verify drainage for hidden lifts — from sump pit dimensions to electrical conduit placement — ensuring compliance with DDA Lift and accessibility standards.
### Lift Pit Drainage
Lift pit drainage refers to the system used to collect and channel water away from a lift pit to prevent pooling, corrosion, or operational failure. In outdoor or semi-exposed sites, even a few millimetres of standing water can cause long-term mechanical issues.
For accessibility lifts like the **Wellington Lift** or **Kensington Stairlift**, drainage must be integrated into the early design phase to maintain the hidden aesthetic while meeting safety standards.
### Why Pit Drainage Is Critical in Lift Design
Every retracting or rising platform lift relies on a dry, stable base. Because the mechanical frame and hydraulic pack are lowered into the pit during installation, any misplaced pipe or duct can block the lowering path.
Sesame engineers emphasise that drainage pipes and conduits must only be installed after the lift frame is positioned. Premature placement can damage components or cause misalignment.
This approach was crucial during a recent **Wellington Lift** installation at a heritage site, where a misplaced sump pipe initially clashed with the lowering path. By adjusting the conduit timing and repositioning the sump pit 50 mm west, the team prevented structural interference — saving several days of rework and ensuring full compliance with the accessibility specification.
### What Are the Ideal Dimensions for a Lift Sump Pit?
The standard sump pit size is 300 mm × 300 mm × 400 mm deep, positioned near the west wall of the pit. This location keeps it clear of the levelling feet and hydraulic pack, allowing for proper drainage without obstructing the lift structure.
In most DDA Lift installations, this configuration provides adequate water clearance without compromising pit integrity. However, the exact location should always be confirmed before the concrete pour and verified against the final lift manufacturer’s pit drawing revision (e.g., "Rev 10").
### Understanding the Top Step Riser (SCSR)
The Top Step Riser (SCSR) is a universal reference point used in Sesame engineering drawings. It represents the vertical distance between the topmost step or plinth and the lift platform datum — typically around 370 mm on heritage projects.
All conduit and sump pit measurements are taken relative to this riser, ensuring uniformity across all lift installations and making it easier for site teams to align pit components accurately.
### How Should Electrical and Hydraulic Conduits Be Routed?
Two 100 mm diameter ducts are cast into the pit’s west wall for hydraulic hoses and network cables, aligned precisely to the SCSR reference.
Additional Ø36 mm conduits are often required for step lighting, especially on heritage or outdoor projects. These lighting conduits are routed through the pit but coordinated with the lift design to prevent interference.
As seen on the **Whitehall DDA Lift**, incorrect routing of lighting conduits can obstruct the hydraulic lines if not checked early — reinforcing why close coordination between architects, electrical contractors, and lift engineers is essential.
### Common Coordination Challenges on Site
1. Early conduit placement can block lift lowering paths.
2. Omitted drainage holes from early drawings lead to site delays.
3. Incorrect reference levels cause misalignment between pit structure and lift geometry.
4. Overlapping step lighting conduits require re-routing after casting.
By verifying these elements before the pour, project managers can save time, cost, and potential rework.
### Lessons for Architects and Contractors
- Always mark sump pits and conduits on lift pit drawings before concrete work begins.
- Confirm all reference points using the SCSR or agreed top step level.
- Coordinate with lift engineers to confirm sump location after the frame is placed.
- Review pit drawings with the site team — especially on listed or heritage projects.
### Relevant Sesame Products
This pit drainage coordination method applies to many of our hidden accessibility lifts, including:
- **Wellington Lift** – for heritage or chapel sites where drainage must be concealed.
- **Kensington Stairlift** – designed for limited-space, indoor DDA-compliant access.
- **Whitehall DDA Lift** – integrates advanced pit drainage for outdoor exposure.
### Further Reading
- “How Hidden Platform Lifts Preserve Historic Entrances”
- “Understanding Pit Design for Short-Rise Accessibility Lifts”
External reference: see national guidance from the Chartered Institution of Building Services Engineers (CIBSE) on lift drainage best practices.
### Frequently Asked Questions (FAQ)
**What is lift pit drainage?**
It’s the process of managing water around a lift pit using sump pumps, drains, and conduits to prevent flooding or corrosion.
**How deep should the sump pit be?**
Most sump pits are 300 mm × 300 mm × 400 mm deep, but this varies with site conditions and lift model.
**Where should I position the drainage hole?**
Always locate it on the pit’s west side, away from hydraulic pack fixing points and moving parts.
**When should I install sump pipes?**
After the lift frame is lowered — installing them too early can block or damage the A-frame structure.
**What is the Top Step Riser (SCSR)?**
It’s a 370 mm reference height used by Sesame to align all pit and conduit measurements accurately.
**Are all accessibility lifts required to have drainage?**
No. Indoor systems like the **Kensington Stairlift** may use alternative moisture-control designs.
### Call to Action
To discuss drainage drawings or confirm pit coordination details, book a Teams Meeting with one of our Project Managers here: https://www.sesameaccess.com/b...