33 Cavendish Square

Project Overview

We provided the complete temporary works design for the external maintenance programme at 33 Cavendish Square — the 1960s Portland stone and granite-clad office tower that stands over Holles Street just north of Oxford Street in London’s West End. Minerva Building Restoration returned to the building to carry out DOFF steam cleaning of the granite and Portland stone cladding panels, Portland stone repairs and redecoration of the previously painted metal windows across every elevation.

Node’s scope covered all three access systems on the project: the fixed tubular access scaffold to the lower blocks, the scaffold support gantry carrying the mast climbing work platform, and the MCWP installation itself. Node designs scaffold, MCWP and hoist installations as one service, so every element the stone, cleaning and decoration trades would work from came from a single consultancy rather than being designed separately and reconciled on site.

The Design Challenge

The two parts of the building called for two different access solutions. On the tall, narrow tower elevations a mast climbing work platform was the preferred option, giving the cleaning and stone repair teams a single moving deck that could be set at any level without a full-height fixed scaffold. On the lower blocks, a conventional sheeted access scaffold gave the stone repair and redecoration teams enclosed working platforms at every lift. Both sit on a busy West End corner beside the Market Halls food hall, with heavy pedestrian footfall and a live ground-floor entrance to maintain beneath the working area throughout the programme.

A twin-mast MCWP was designed to run the full height of the tower elevation, with a sheeted platform giving the DOFF cleaning and stone repair operatives a clean, enclosed deck that could be positioned at any level of the façade. Rather than founding the masts at street level, the MCWP bears onto a purpose-designed scaffold support gantry spanning the entrance and pavement, so the ground floor stays open and protected below. The gantry was designed for the mast base reactions and platform loads, with the mast tie forces into the façade resolved at the same time and tie positions coordinated against the granite and Portland stone panel layout so nothing was fixed through cladding that was itself being cleaned and repaired. The lower blocks received a fully sheeted independent tubular scaffold with an external staircase tower, designed for the wind loads on the sheeted enclosure and tied back to the podium structure.

What Node Delivered

A single, coordinated design package covering every access system on the project: the full-height MCWP installation with its tie layout to the tower façade, the scaffold support gantry carrying the mast bases over the live entrance and pavement, and the fully sheeted independent access scaffold and staircase tower to the lower blocks. 2D drawings, a full 3D model and structural calculations were issued for each element against a common set of load assumptions, so the scaffolding contractor, the MCWP installer and Minerva’s stone and decoration teams were all working from one design rather than three. The result is a West End façade programme running from fixed scaffold alongside the installed mast climber, with the entrance to 33 Cavendish Square kept open underneath for the duration.