Making it right

The best of intentions on eco credentials can cause a poor outcome for fire safety. Perega offers this case study as an example of addressing the legacy of early eco schemes.

When a fire broke out at Sinclair Meadows in South Shields, the cause was traced to a fault in the building’s solar PV array. The development, a 12-flat residential block completed in 2012, was celebrated as one of the UK’s first carbon-negative residential schemes. Following the fire, a detailed investigation identified several previously unknown issues within the timber-frame structure, prompting a remediation to enhance the building’s fire resilience.

The fire had destroyed a quarter of the roof and caused extensive water damage to three flats. To understand the true ‘as-built’ condition and identify all underlying risks, a comprehensive strip-back of the fire-damaged flats to the original timber frame was deemed necessary. This allowed engineers to analyse the building’s construction details in a way that typical non-destructive surveys cannot. 

The investigation brought to light several design and construction issues that required addressing to meet current regulations (though it was compliant at the time of build). For example, the original fire barrier in the roof space prevented effective cross-ventilation (though thankfully the timbers were undamaged). To resolve this, the fire-stopping strategy was redesigned to protect the building from fire spread while preventing moisture build-up and interstitial condensation, thereby protecting the timber frame for years to come.

An engineered solution 

The primary engineering challenge was to enhance the building’s fire compartmentation without compromising its original energy-efficient functionality. A fire-stopping strategy ensured new barriers integrated seamlessly with the existing structure:

• the large roof overhang was re-engineered so that the overhang itself acted as the fire barrier
• the redesign removed the need for ventilation-blocking internal barriers, maintaining the airflow required for timber health
• specialist fire-stopping in the form of ACO fire slabs were installed between the roof membrane and wall tops, with ACO wired fire batten barriers installed at all fire compartmentation locations; and
• compliant fire breaks were installed within the external walls at party wall junctions and meticulously fitted around all window and door openings to ensure full compartmentation.

The remediation required a new fixing arrangement for the increased insulation thickness and cladding. It necessitated long screw fixings however, due to edge distance limitations in the vertical timber studs, these were unsuitable. Plywood was fixed to the timber studs to provide a secure, solid substrate for the new, longer insulation and cladding fixings.

A key element of the project was modernising the building’s safety profile while maintaining its functionality and original timber-frame structure. The remediation was not merely about repair, but about future-proofing.

The original combustible larch cladding and timber shingles were replaced with a non-combustible Metrotile system. This significantly reduced the risk of external fire spread while simultaneously resolving ongoing maintenance issues associated with the original timber exterior. In addition, all mechanical and electrical systems were restored to current standards, including a like-for-like replacement of the heat-recovery units to maintain the building’s energy-efficient specifications.

The project illustrates how specialist building pathology can enhance early sustainable designs. As Darren Parkin, Senior Technician at Perega, says: “The Sinclair Meadows project presented a unique opportunity to not only repair the fire damage but fundamentally improve the building’s safety.”

For more, visit perega.co.uk