INCA Case Study: Corbett House, Bristol

Background and Requirements

In 2023, Corbett House, a 14-storey residential tower block in Bristol, was identified by Bristol City Council as a potential risk due to its external wall insulation (EWI) system, which no longer met the stringent safety regulations introduced across the UK for high-rise buildings over 18 meters following the Grenfell tragedy.

The building not only posed a fire hazard due to its combustible white EPS EWI system but also suffered from poor thermal performance, impacting residents’ quality of life. Additionally, years of exposure to the unpredictable British weather had left the façade looking dull, dreary, and aged.

Recognising the urgency and complexity of the refurbishment, Bristol City Council selected K Systems for the project, owing to its industry-leading expertise and reputation for delivering high-quality builds across the UK. K Systems had previously completed several award-winning transformations, making it the ideal choice for this critical project.

The primary objectives for the Corbett House refurbishment were:

• Remove the non-compliant EWI and replace it with a government-approved EWI system
• Enhance the fire safety credentials of the residential building
• Improve thermal comfort for residents

Additionally, Bristol City Council requested a unique, modern aesthetic for the building to significantly upgrade its appearance and attract potential residents.

K Systems collaborated with Fineline Architectural Design Ltd and Synergize Ltd to execute the refurbishment. This partnership successfully transformed Corbett House from a drab and potentially dangerous structure into a stunning and safe residential tower, setting a new standard for high-rise refurbishments in the southwest of England.

Solution, Specification and Results

After a comprehensive scoping process that considered the requirements of Bristol City Council, project objectives, budgets, and timeframes, K Systems specified the industry-proven M VBriQ+ and M Silicone TC insulation systems for the project – both being Mineral Wool insulation systems, with either a clay brick-slip or silicone thin-coat render finish. This system was chosen to address safety concerns, update the aged façade, and significantly enhance the building’s thermal performance, but also for the additional reasons stated below:

• The M VBriQ+ system is A1 Classified which offers the highest standards of fire safety for the critical lower building levels
• It has a traditional real clay brick finish providing an authentic brick appearance
• It is extremely lightweight, lighter than traditional brick construction, which makes it faster and easier to install
• It is BBA Certified, ensuring quality and performance
• It has a durable finish, offering category 1 impact resistance, making it perfect on the ground-floor levels where there is higher footfall
• It is extremely cost-effective, which makes it more economical than traditional brick finishes

In small areas of this tower block, predominantly where balconies used to be situated, K Systems’ Direct Fix EWI was utilised. Direct Fix is an Agrément-certified system designed for direct attachment to both low and high-rise sheathed, steel-frame building structures.

The Direct fix system provides up to four top-tier finishing options: the A1 fire-rated Mineral TC and VBriQ+ Clay Brick Slips, as well as VBriQ Acrylic Brick Slips and Silicone TC render finishes, and, as a cost-effective solution, ensures a quick and straightforward installation process meaning installation teams can complete jobs faster, improving labour intensity and labour resource required.

140mm Mineral Wool insulation was also specified for the refurbishment, providing exceptional thermal insulation, acoustic performance, and fire resistance. Additional benefits of Mineral Wool insulation include:

• Thermal and acoustic integrity, ensuring a snug fit between frames in walls, partitions, floors, and roofs
• Zero wastage as there is minimal need for cutting, resulting in efficient use of materials
• Contains no gases with Ozone Depletion Potential (ODP) or Global Warming Potential (GWP)

With the VBriQ+ finish applied to the lower levels of this retrofit, the upper levels of the project were completed with K Systems Silicone TC15 – a thin-coat render finish.

Silicone TC15 is an organic resin render with a textured finish. It is extremely water repellent, protecting the building from moisture, is fully breathable, helping prevent dampness in buildings, and possesses an A2 fire rating which helped improve the overall safety credentials of the residential tower block, which was one of the main refurbishment objectives.

Challenges

The refurbishment project at Corbett House in Bristol presented several significant challenges.

Minimal on-site storage and difficult site access necessitated the K Systems team to implement a customised delivery service, ensuring minimal disruption and preventing unsafe storage practices in the vicinity of the area.

The transition from steel frame construction to masonry construction posed another hurdle; however, K Systems addressed this by providing robust detail and transition designs to ensure a consistent finish and technically suitable and durable system design. To support installation teams, the K Systems technical team provided training, facilitating smooth and practical transitions to be achieved on site. With all systems used being Agrément certified, the performance and durability of the systems could be assured.

Additionally, long lead times for Mineral Wool materials were a concern at the outset of the project. However, keen to mitigate this and ensure the project was completed within the agreed timeframe, K Systems’ sales and supply chain teams conducted weekly material planning meetings, ensuring continuous supply and preventing any work stoppages due to material shortages.

Whilst challenges were present during this project, the above showcases K Systems’ ability to implement effective solutions which overcome any challenges or barriers to completion.

Completed Project

The transformation of Corbett House exemplifies K Systems’ innovative and creative approach in the industry, prioritising both safety and quality.

In 2023, K Systems undertook the refurbishment of Corbett House, a 14-storey residential tower in bustling Bristol. By March 2024, the building was transformed from an unsafe structure in breach of current government regulations, with poor thermal performance, into a modern, safe haven.

The project achieved a significantly improved U-value rating of 0.24 W/m²K, the highest standard fire safety rating, and an enhanced exterior finish that revitalised the entire residential block, making it more appealing to potential residents. Significantly, the project also contributed to Bristol City Council’s decarbonisation strategy while supporting residents with a reduction in energy usage and energy bills.

Throughout the refurbishment, the K Systems team made weekly site visits to ensure the highest levels of quality workmanship. Scheduled installation phases were completed on time, and there was a constant stream of effective communication between all parties involved.

This commitment to excellence, coupled with the team’s expertise and professionalism, resulted in 100% satisfaction from the client, Bristol City Council.

Testimonials

Daniel Baker, Synergize:

“It was a pleasure to be working alongside K Systems on the tower block refurbishment of Corbett House. The requirement was a full strip out of the existing cladding and upgrading the cladding using Mineral Wool insulation.

“Everything from the planning of the project, the ordering of materials and the site visits from K Systems to sign off the works undertaken is second to none. They delivered a great service and together we made this refurbishment a successful project.”

Glen Lewis, Synergize:

“From inception to completion, K Systems played a critical role by supporting Synergize and Bristol City Council in preparing specifications and agreeing on all detailing to meet current Building Control Regulations. Their commitment was evident through numerous site visits before the tender process, during the works, and upon completion. K Systems’ proactive approach and thoroughness were key in maintaining project momentum and quality.

“Synergize’s collaboration with K Systems was exemplary. All teams worked seamlessly together, showcasing absolute trust in each other’s skill, vision, and judgement. This was particularly evident in the precision and quality of the work delivered. The partnership ensured that each aspect of the project was handled with the utmost care and professionalism.”