Soda Blast Cleaning & Stone Restoration

Barclays Bank - Bridgend, South Wales, CF31

Client's Challenge

Barclays Bank required specialist façade cleaning and restoration support as part of a wider refurbishment programme at its Bridgend branch in South Wales.

The building is a historic listed property, meaning all cleaning and restoration works had to be undertaken using non-aggressive, conservation-led methods to avoid damage to sensitive masonry and Portland stone substrates. A key concern for Overbury Plc, acting on behalf of Barclays, was identifying a cleaning solution capable of removing environmental pollution and biological staining without altering the surface profile of the stone.

In addition to the external works, the refurbishment programme included internal restoration elements, such as window replacement, ornate carpentry
replication and lime plaster repairs, all requiring strict specification compliance and attention to historic detail.

Due to the nature of the client and building, the project also demanded strict security controls, out-of-hours working, and seamless coordination to ensure the wider refurbishment programme remained on schedule.

Assessment & Planning  

APT ICC attended site meetings with Overbury’s project management team
to assess:

• The condition of the historic stone façade and levels of environmental contamination
• Risks associated with cleaning sensitive masonry and Portland stone
• Suitability of soda blasting as a controlled, non-destructive cleaning method
• Requirements for stone reinstatement and façade integration
• Internal restoration scope, including joinery replication and lime plaster repair
• Security, access and out-of-hours delivery constraints

Controlled trial soda blast cleaning samples were undertaken on selected areas of the façade to demonstrate effectiveness and confirm substrate safety. Once approved, APT ICC developed a detailed delivery plan aligned with conservation requirements, security protocols and night-working constraints.

    Methodology

    Step 1 – Trial soda blast cleaning and approval
    Controlled soda blast trials were carried out on masonry, Portland stone and terrazzo columns to validate the cleaning approach and confirm safe removal of pollution staining and biological growth.

    Step 2 – Full façade soda blast cleaning
    Following approval, soda blasting was undertaken across the building exterior to remove years of environmental build up while preserving the integrity of the historic stonework. Soda blasting was selected for its ability to clean effectively without aggressive abrasion.

    Step 3 – Stone reinstatement works
    The existing exterior night safe section was carefully removed and reinstated using reclaimed Portland stone. Specialist stone craftsmanship ensured seamless integration with the original façade.

    Step 4 – Internal joinery and window restoration
    Replacement oak-framed window units were installed to match existing designs. Ornate internal carpentry elements were replicated and fitted to maintain architectural continuity.

    Step 5 – Lime plaster repairs
    Lime plaster repairs were completed throughout the building to specification, delivered under restricted timeframes using night-working schedules.

    Step 6 – Secure out-of-hours delivery and handover
    All works were delivered under strict security controls, with controlled access and safe handover procedures throughout the programme.

    Site Access & Logistics

    Equipment
    • Soda blasting systems with controlled pressure and media delivery
    • Access and protection equipment suitable for historic façades
    • Specialist stoneworking and joinery tools
    • Lime plaster repair tools

    Chemicals
    • No chemical cleaning agents required
    • Façade cleaning achieved using soda blasting only, selected for its
    non-destructive properties

    The Results
    • Historic stone and masonry façade cleaned safely with no substrate damage
    • Environmental pollution and algae staining fully removed
    • Night safe section reinstated seamlessly using reclaimed Portland stone
    • Internal joinery and window replacements matched original designs
    • Lime plaster repairs completed to specification within tight timeframes
    • Works delivered securely, out of hours, and on programme

    The completed works were extremely well received by both Overbury Plc
    and Barclays Bank, demonstrating APT ICC’s capability to deliver high-quality,
    conservation-led cleaning and restoration works within high-security, listed building environments.