Client: Liverpool Housing Action Trust
Project: Liverpool housing estate. The 14- and 15-storey brick clad buildings were mainly built in the 1960's
Type of works: cavity wall stabilisation of tower blocks using Tiefoam.
Liverpool Housing Action Trust is a non-departmental government body established in 1993 to secure the improvement of tower blocks in Liverpool over a 10 year period, with aid of funding from the Department of the Environment.
Surveys carried out by Curtains Consultant Engineers in 1995 identified structural deficiencies to the external masonry cladding, that was in danger of coming away from the buildings. Scaffolding and fencing was immediately put into place around the blocks until an appropriate repair solution was found.
In conjunction with Curtains, MPI carried out test installations that resulted in Tiefoam being assessed as the best option for repair. Works began in November 1996 with MPI as specialist sub-contractor to Tarmac Contract Housing as main contractor.
Works have proceeded at the rate of one block per week. With the stabilising system in-situ the householders are also able to enjoy the benefits of upgraded insulation as Tiefoam is a leading insulation material commercially available with a k value of 0.025W/mK.
Once injected, the Tiefoam system expands and hardens, forming a solid bond between inner and outer skins, thus stabilising walls. External installation meant minimum disruption, with the householders able to remain in residence whilst the project was undertaken.
The areas requiring stabilisation were identified by structural consultants. The panels requiring stabilisation were drilled with a staggered pattern of small bore 12mm holes. These holes doubled as inspection and injection. The cavities were inspected using a checkscope and all blockages were identified. Bricks were removed, cavities cleared and brickwork made good, followed by a second inspection.
During these works arrangements were made with the residents to gain access and carry out an internal inspection. Particular attention was paid to any areas where leakage was considered possible, primarily sealing small cracks around window frames with silicone sealant.
The panels were then foam filled from the outside in a sequential manner and the injection holes made good with mortar. Finally, the exterior of the building was power washed and the scaffold removed.
Tiefoam is certified to BBA 97/3426, as are MPI as installers.