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By admin | Published: December 10, 2011

CaseStudy – Ballymun Wall Ties

Project Details

Ballymun Wall Ties
  • Client: Dublin City Council
  • Location: Ballymun Towers, Dublin
  • Main Contractor: Larsen Contracts Ltd
  • Application: Wall tie replacement
  • Market: Residential-Public Sector

The Ballymun housing estate was created in the early 1960s as an opportunity to re – house people in better homes. It achieved much of this by adopting fast-track construction methods of high rise construction. Some weaknesses of these systems became apparent with the passing of time.

The site-fabricated,tilt up, external reinforced panel system was fixed to the RC frame with a patent steel tie inside a part insulated cavity. Over time, the waterproof jointing system would degrade and fail, allowing moisture ingress into the cavity corroding the ties. Engineering surveys concluded that there was a high risk of tie failure which could result in the possible collapse and fall of a reinforced concrete cladding panel in a densely populated residential area. Larsen Contracts were successful in their tender for the phase 1 & 2 works for remedial replacement of 85,000 wall ties installed on all 15, eight & four storey blocks throughout the Ballymun Complex. The extensive, open site housed 22,000 people which shows that this site was pretty unique and required an innovative approach to Health & Safety as well as the repair works methodology . The tender called for traditional access, this in itself could lead to potential Health & Safety issues as the overnight security was almost impossible to maintain. Larsen identified rope access as a much safer and suitable solution, where control of the working environment would be established and removed in a number of locations on a daily basis. The work tasks involved drilling anchor holes through the external panel and into the RC structure, installation of a high strength stainless steel wedge anchor and stainless bolts. Abseilers were able to carry all tools on their work belts and comfortably carry out the installation in a safe and efficient manner. The work space below was isolated and a safe work area established each day and maintained by a grounds man to prevent unauthorised access. With a team of 30 highly trained rope access specialists, the project was concluded without incident in half the original programme time, limiting the disruption to residents and providing huge savings for the client.