Disputed Trellick Tower window replacement gets go ahead

The original windows on London’s landmark Trellick Towers were ahead of their time, so it is only right that the replacements should make the most of modern technology. However, it’s not quite that simple.

Despite much criticism the Trellick Towers window replacement and repairs plans have gained planning and building permission. Project Manager David Williams, Ark Consultancy, hopes to start work on the Grade II* (the star indicates a level above Grade II) listed building within the next seven months.

Building conservation groups, the Twentieth Century Society and DOCOMOMO, and some residents wanted the windows to be repaired rather than replaced. These groups feel that the windows, designed by architect Erno Goldfinger, are a vital element of the building and contribute to its architectural integrity.

However, the Government Office for London, responsible for granting planning and building permissions for listed buildings, decided that, ‘the works for which listed building consent is sought are acceptable as far as the special architectural and historical interest of the building are concerned’ and permission was granted. A delicate balancing act David Williams said: ‘[The window design] has been a huge area of negotiation with the statutory authorities and as a result changes have been introduced.’

Although the designs have been amended Cordula Zeidler, Twentieth Century Society, was disappointed with the decision to grant permission and said: ‘The campaigners’ specific queries had not been answered.’ She also felt that the replacement frames were thicker and less elegant.

However, Trellick Tower is social housing, so the replacement windows were subject to the Decent Homes standard.

David Williams said: ‘It has been difficult to balance the development and improvement in window hardware and glazing technology with the visual concepts of the design and it has been something that the project managers have been very aware of and sensitive to.’

The project managers have three years, starting from April 2006, to begin work and are waiting for the council to sign off the plans. Kensington and Chelsea Borough Council and the Tenants’ Management Organisation are reviewing the scheme and David Williams hopes this process will be completed by early October.

It has been difficult to balance the development and improvement in hardware and glazing technology with the visual concepts of the design

Experimental glazing

The original glazing used was an experimental double glazing from Pilkington. It was a 1.2metre x 1.2m pane, which was made double the size required, then folded over on itself and sealed to create a space between the panes. It was the forerunner of modern double glazing.

Now the project managers want to improve the thermal efficiency for the residents so modern double glazing will be used which needs deeper rebates to accommodate it.

Most of the original windows are pivot windows, which are ‘no longer fashionable’ and are vulnerable to high winds, particularly at the top of the 31 storey tower. The pressure can cause window distortion and damage the weather stripping. The replacement windows will be multipoint locking systems, rather than pivot, and it has been agreed that similar ironmongery will be used and that the original ironmonger, Ferco, will make the new hardware.

However, this change in style means that there is more ironmongery to fit into the frames and so sections need to be larger. Balcony doors also need more ironmongery.

The overall budget of £8.5million includes the work on the windows, however a specific amount has not been allocated, while £1.2m has been allocated for the scaffolding, which will also be used for the main masonry refurbishment.

The project design team that worked on the window designs includes lead design consultants, John Shreedes who are building surveyors and will be the contractors and administrators on site, John McAslan + Partners, who are experts in building conservation, Kumar Associates, who are structural engineers, cbe Partnership who are quantity surveyors and Reef Associates who are façade access consultants.