Case Study: External Structural Repairs to High Rise Flats in Northampton

Client – Northampton Borough Council, Housing Department

Location – St Katherines Court, Castle Street, Northampton

Contract Value – £350,000

Contract Duration – 16 weeks

The Problem: External Structure Defects

Prior to the injection of cavity wall insulation, Northampton Borough Council commissioned a structural survey of this high-rise block which contains 40 fully occupied flats including a number of tenants who were vulnerable or had special needs.

The report identified a large number of defects to the external structure, principally to the concrete frame, parapet, balconies, and brickwork infill panels. The condition of the external concrete was particularly poor, numerous sections of concrete had broken away and fallen to the ground leaving the steelwork reinforcement exposed and corroded.  Problems with the brickwork infill panels had been caused by wall tie corrosion, exposure to the elements and the absence of expansion joints.

The Solution: Structured, Holistic Project Approach

Based on our extensive experience in the specialist structural techniques required to address the problems and our understanding of social housing requirements we were selected to:

  • Insert expansion joints into the brickwork parapet wall
  • Re-bed and seal the concrete coping stones
  • Install retro ties into sections of the external cavity brickwork
  • Removal and re-building of bulging brickwork panels
  • Crack stitching to external brickwork
  • Repairs to spalled concrete to the main frame, concrete lintels and sub-cills
  • Replacing sections of corroded steel balustrades
  • Applying anti-corrosion treatment to exposed reinforcement
  • Waterproof treatment to open concrete balconies
  • Re-decoration of rendered walls with masonry paint

Due to the nature of the work and the environment, Health and Safety requirements were paramount and in partnership with the client and their consultants, detailed risk assessments and method statements were prepared and agreed with all stakeholders prior to commencement of the work.

The flats were fully occupied during the course of the work and close contact by our liaison officer with the residents ensured that the minimum of disruption was caused, the work was programmed on a floor by floor basis and written notification together with personal contact minimised disruption to the tenants.

At each stage of the work inspections were carried out by an independent structural engineer who recorded the completed works and signed them off against the recommendations in the original report.

During the course of the work a number of unforeseen problems were encountered, unseasonably cold weather restricted the use of temperature sensitive products, to resolve the problem temporary polythene enclosures and space heaters were used to create a stable temperature during the product curing times.

The Outcome: Completion on Schedule and on Budget

The contract was successfully completed within the agreed programme dates and strictly in accordance with the detailed requirements of the consulting structural engineer and within the clients budget.