Case Studies

Rooftop Solar Access: Stair Tower Design and Installation in Devizes


Client: CNC Manufacturing Facility
Location: Devizes, UK
Scope: Design, fabrication, and installation of a rooftop access stair tower for solar panel maintenance

The Project


Our client operates a large-scale CNC machining facility, manufacturing components for the automotive and aerospace sectors. As part of a wider sustainability initiative, they recently installed a rooftop solar array across the facility’s 9,000 m2 roof space to generate clean, on-site energy.

To support safe and efficient maintenance of the new solar system, RHW Engineering was engaged to design and install a permanent rooftop access stair tower.

Project Requirements


Through consultation, we identified several key access requirements:

  • Enable authorised personnel to carry out cleaning and maintenance of the rooftop solar array
  • Ensure equipment could be carried safely to the roof
  • Restrict access to prevent unauthorised use
  • Balance cost-efficiency with long-term safety and durability

The client clarified that rooftop access would be infrequent, but must be safe, secure, and practical for carrying light equipment.

Design Considerations


Stair towers are governed by their intended use, frequency of access, and the type of load expected. For this project:

  • The rooftop sits 7 m above ground level
  • The structure needed to allow safe manual transport of equipment
  • A modular, low-maintenance solution was preferred

We proposed a steel stair tower using open mesh grid treads and landings for slip resistance and drainage. The tower consists of four short stair flights, each rising 1.5 m, with intermediate landings and a final landing platform that extends onto the roof.

Site Survey and Ground Conditions


The factory site includes front and rear car parks running parallel to the building. Working with the site’s Facilities and Maintenance Manager, we selected a location within a block-paved area for installation.

During ground surveys, we discovered a large soakaway crate system beneath the chosen site — not marked on utility drawings. Because RHW was handling the project end-to-end, we were able to respond quickly: we revised the stair tower design to avoid ground excavation and repositioned the tower to a new location.

This redesign included:

  • Adjusting stanchions to be bolted at surface level rather than embedded
  • Incorporating a “step-over” stair design at roof level for safe access over the parapet

Installation and Final Design


The completed stair tower includes:

  • Galvanised steel construction for corrosion resistance
  • Open mesh treads and landings
  • Access control via a mesh cage enclosure
  • Modular assembly for efficient installation

We pre-assembled the tower sides and stair stringers at ground level. A local Hiab lorry company assisted with lifting the components into place, allowing for efficient modular installation.

Conclusion


RHW Engineering delivered a durable, low-maintenance stair tower that provides safe rooftop access while meeting all client requirements for safety, functionality, and access control — all within the original project timeline.