Intrusive Façade & Structural Survey

Project Overview

Neilcott Construction Ltd commissioned OMNIA Building Consultants to undertake an intrusive structural and façade assessment of the existing building at 66 South Lambeth Road, forming part of the Kings College Hospital NHS FT Sexual Assault Referral Centre (SARC). The building comprises a three‑storey reinforced concrete (RC) frame with precast plank floors and a steel‑framed pitched roof. The assessment was required to understand how the existing façade interacts with the structural frame and to inform future refurbishment and compliance works.

The survey was completed between 18–20 February 2026 and included opening‑up works, borescope inspections, and exposure of façade and structural elements across multiple elevations and floors.

Project Objectives

The objectives of the survey were to:

• Confirm the presence and adequacy of cavity closers at windows, doors, louvres, and party wall interfaces.

• Identify the type and thickness of insulation within the cavity wall construction.

• Determine the position of RC beams, columns, and frame elements in relation to façade openings.

• Establish whether windposts or secondary structural supports were installed.

• Assess how the external façade, including ductwork and feature window areas, is supported.

• Provide the design team with clear structural and façade information for refurbishment planning.

Project Execution

Scope of Works

The intrusive survey comprised:

• Localised removal of façade elements, including windows and louvres.

• Endoscopic inspections into the cavity at selected locations.

• Opening‑up works to expose wall ties, RC columns, and slab edges.

• Inspection of cavity insulation, cavity closers, and façade support components.

• Review of timber‑framed infill areas and roof structure elements where accessible.

• Photographic and written documentation of findings for design team reference.

Key Findings & Recommendations

Key findings Include:

• The building was confirmed to be a reinforced concrete frame with non‑loadbearing masonry infill walls, generally performing as expected.

• Wall ties were in good condition with spacing typical for RC‑framed construction.

• Steel lintels supporting brickwork over openings showed no signs of distress.

• Cavity closers were inconsistently installed. Many were simple plastic strips without insulation or fire‑rated properties, and no cavity fire barriers were found at floor slab interfaces or around louvre openings.

• Insulation varied in thickness between 25–50 mm and was sometimes used as a makeshift cavity closer instead of a proprietary system.

• The party wall lacked insulation, wall ties, and fire‑stopping, raising compartmentation concerns.

• No windposts were identified, aligning with the structural behaviour of RC‑frame buildings.

Recommendations included:

• Installing proprietary insulated and fire‑rated cavity closers at all openings.

• Introducing cavity fire barriers at floor levels.

• Improving insulation continuity.

• Upgrading party wall fire separation.

• Undertaking full roof‑edge inspection during future refurbishment works.

Challenges & Solutions

Challenge

Access to certain roof areas and complex cavity zones was restricted, while non‑uniform cavity widths and irregular RC frame geometry made inspections challenging.

Implication

These limitations prevented full verification of some construction details, particularly roof‑edge conditions, cavity fire‑stopping, and insulation continuity. This required careful interpretation of partial exposure to avoid inaccurate assumptions.

Solution Implemented

Strategic targeted opening‑up was combined with borescope inspections to maximise coverage. Areas where ceilings or windows had been removed were utilised for indirect viewing, and the contractor coordinated safe removal and reinstatement to minimise disruption.

Challenge

Uncertainty initially existed around the structural role of the curved external concrete columns forming part of the building’s architectural façade.

Implication

Without clarity, the design team could not safely assume load paths or determine façade support requirements around the large window zones.

Solution Implemented

Intrusive exposure of the steel plate connections revealed that the columns act as local façade restraints rather than primary load‑bearing elements. This confirmed the structural behaviour and informed the design team’s refurbishment strategy.

Challenge

Removal of window and louvre units carried risks of damaging finishes, exposing internal areas to weather, and interfering with ductwork connections.

Implication

Uncontrolled works could compromise building integrity and disrupt operations within the facility.

Solution Implemented

A sequenced and controlled removal process was adopted, ensuring that all exposed openings were made safe and weather‑tight. Collaboration with the contractor ensured careful reinstatement and minimal operational impact.

Challenge

The absence of clear cavity fire‑stopping and inconsistent cavity closer provision raised potential compliance concerns.

Implication

Gaps in fire compartmentation could lead to non‑compliance with current Building Regulations and significant remediation requirements.

Solution Implemented

The survey documented all deficiencies, enabling the design team to plan a comprehensive upgrade incorporating fire‑rated cavity closers, appropriate cavity barriers, and improved party wall fire‑stopping as part of forthcoming works.

Client Outcome

The intrusive investigations have provided Neilcott Construction and the wider project design team with a clear, accurate, and evidence‑based understanding of the façade construction, structural interfaces, and areas requiring improvement.

The building’s primary structure was confirmed to be performing well, with key areas of concern relating mostly to fire‑stopping, cavity closure quality, and insulation continuity.

Armed with detailed findings and targeted recommendations, the client can now progress refurbishment design with confidence, ensuring compliance with modern standards and delivering long‑term improvements to the building envelope and safety performance.