Customer Request

Our customer was approached by a company renovating a listed building.  The building had a 4 storey high WWII observation tower overlooking the Western approach to the Solent, which required an internal staircase and viewing platform.

There were a number of constraints paced upon the design by the unique building and it’s listed building status, requiring assembly within the tower, level by level, adherence to the latest building regulations, and limited contact to the tower walls.

The solutions proposed was a bespoke staircase with four levels including an upper viewing platform, parts cut and galvanised off site – requiring no special tools or jigs for assembly, and parts which could be transported and moved within the tower via the 5x3’ doorway access at the base of the tower. 


AES Requirement

To fulfil our customer’s requirements we had to accurately capture all the internal features and internal dimensions of the tower, assess the potential for fixings within the tower (bearing in mind the latest building regulations and the desires of the customer and their client), as well as appreciate the needs and requirements of the fabricator, and how the parts would be assembled within the tower.



By providing 3D CAD geometry it is possible to check the design was suitable, conformed to the latest regulations and was able to be assembled within the tower, without any geometry conflicts prior to cutting material.  Any issues that we did identify were able to be discussed with the project team, and alternative solutions sought, long before access to the site was required.  This allowed the ongoing renovation to continue unhindered.

Having 3D geometry allows generation of the 2D cut files which could then be sent directly to the laser cutter used for profiling the steel parts, and generation of a Bill of Materials, part assembly drawings, and installation instructions.


AES Method

Accurate measurements were made on-site and a 3D CAD Assembly was created for the entire tower, and the structure within it.  Each and every part was created and defined within the system, allowing use of common parts where possible (to reduce part count and complexity).  Fit and function could then be checked by the relevant persons, prior to creation of the 2D assembly drawings.  This allowed the design to be adjusted to incorporate any feedback from the team prior to manufacture of any parts.

General Arrangement drawings were created, as well as individual part drawings, bill of materials, unique part numbers, part cut files, and structural calculations.

Having the parts pre-cut allowed them to be dip galvanised prior to arrival on-site, so it was important no modifications were required during installation.  Again, the likelihood of achieving this without 3D CAD geometry was unlikely.


Successful Outcomes

Providing our client with the complete solution and our direct integration with the steel supplier allowed all the individual parts to be pre-cut, drilled and galvanised prior to arrival on site. The assembly instructions and parts list gave confidence that the assembly was able to fit within the confines of the tower, and where the required fixing locations would be.

Benefits of the solution were that no additional modification was required to the structure once on-site, and the staircase and platform ultimately achieved Inspection sign-off, both outcomes which our Client believed would have been unachievable without our work.