INCA Case Study: Kelvedon House, Lambeth

Fire safety upgrades at Kelvedon House

Client: Breyer
Measures: Remove defective existing EWI systems and replace with compliant system.

The Challenge

Kelvedon House is residential tower block Located in the London Borough of Lambeth constructed 1968 as part of the Spurgeon Estate. The block comprises of 82 flats over 22 storeys. An external wall insulation system was installed circa mid-eighties, this system was an EPS system mounted on uPVC cavity rails spanning window spandrel panels.

Retrofit UK Ltd were appointed as a subcontractor with the EWI upgrade works by our client and main contractor Breyer PLC, based upon our long-standing industry experience installing EWI systems on social housing and high-rise projects. The objective of the project was to upgrade the external wall insulation system to a fire rated system whilst improving the thermal efficiency, aesthetics and extending the lifespan of the building.

The Solution

Retrofit were tasked with the removal of the existing EWI cavity rail system, which consisted of uPVC horizontal & vertical rails, along with a timber frame to panels below the windows, 120mm EPS insulation board, reinforcing mesh, base coat render and texture coating, together with windowsills made from cement particle board. It became apparent once the old system had been removed that the existing substrate, in particular the panels below the windows were unable to support the new proposed EWI system. A lightweight steel frame (SFS) was designed and installed along with fire stopping and Y wall sheathing board.

As it was only possible to fix the SFS cleats to the floor slabs it made the SFS a major part of the works. Some 60% of the building had SFS installed, and upgrading to an adhesively and mechanically direct fixed EWI system to both masonry and sheathing board. The block was specified with Wetherby’s A2 external wall system complete with stone wool Insulation to a thickness of 120mm, along with the design and supply new aluminium polypropylene powder coated sills complete with support brackets. Wetherby’s system was chosen due to its superior fire performance capabilities along with its excellent thermal & acoustic properties. Stone Wool Insulation is a consistent density, high strength, rock mineral wool slab with a water repellent additive specifically designed for use in external wall insulation systems. Thermal performance caould be maximised whilst also ensuring the  increased long term compressive strength capabilities and high impact resistance making it ideal for use behind Wetherby’s Silicone ‘K’ 1.5mm Render, to circa 3500m2.

The block was given a completely new facelift with white and a bold red silicone render to panels under the windows.