EWI Reinstatement on High Rise Social Housing
Client: Osborne Property Services
Measures: External Wall Insulation
Location: Slough
Date: 2019 - 2020
Value: Approx. £670,000
The Challenge
Cornerstone was appointed to a high profile external wall insulation reinstatement project in 2019, working in partnership with main contractor Osborne Property Services.
The project involved the removal of the existing external wall insulation on two fully occupied 12 storey high rise tower blocks in Langley – Poplar House and Broom House – which are owned by Slough Borough Council.
The works were being carried out in response to fire safety concerns in the wake of the Grenfell Tower disaster. The towers failed a fire safety test, and a costly ‘waking watch’ system had been put in place prior to the works. The existing EWI system comprised an expanded polystyrene (EPS) board.
In addition to the renewal of the external wall insulation, our scope of works included renewal of external pigeon netting, renewal of capping to the roof level and the installation of pattresses upon which new rainwater downpipes could be fitted.
Each block comprises approximately 1,800m2 of wall area.
Our Solution
Cornerstone worked on Broom House first, stripping the existing EWI in less than four weeks. The installation of the new EWI was completed in phases, allowing the scaffolding to be dropped every few floors. On completion, the same programme of works was undertaken on Poplar House.
The system that Cornerstone has installed back onto the blocks is the Wetherby Building Systems’ Stonewool Silicone External Wall Insulation system – a 100mm non-combustible system with a Class 1A fire rating.
Cornerstone employed a highly experienced and dedicated Site Manager to oversee the works and coordinate our activities with the main contractor and scaffolder and manage a team of twelve highly skilled installation engineers.
The Result
Despite challenges outside of our control, including inclement weather and COVID-19, the work was delivered to the complete satisfaction of our main contractor client and Slough Borough Council, achieving a clean, bright and uniform finish that reinvigorated the blocks. Cornerstone provided an excellent level of technical expertise and crucial operational flexibility to ensure the project was delivered compliantly and efficiently.
The new insulation provides peace of mind for the blocks’ tenants, for whom fire safety was a primary concern. They have also been enthusiastic about the refreshed appearance of the blocks, and the maintenance of the levels of energy efficiency the insulated towers achieve.
A robust manufacturer’s guarantee provides further comfort for Slough Borough Council.
In total, approx. 3,600m2 of EWI was removed and reinstated

