Tate Modern extension: planning application submitted

A previous design was approved by Southwark's planning committee in March 2007 with work expected to commence in September 2008, but last summer the gallery revealed a revised design with a brick lattice facade instead of the previously envisaged glass.

At the heart of the new plans are the vast oil tanks of the former Bankside Power Station which will be retained as raw spaces for art and from which the new building will rise.

Tate says that the use of brick is more sympathetic to Giles Gilbert Scott's power station building but the extension by Swiss architects Herzog & de Meuron will use the material in a radical new way by creating a perforated brick lattice through which the building will glow in the evening.

The project will also address some of the strains on the current building. The gallery was originally designed for 2 million visitors. With current visitor numbers exceeding 5 million, there is serious overcrowding, particularly at weekends.

Curators say that changes in contemporary art practice mean that different kinds of spaces are desirable and additional space is needed so works can be brought out of storage and shown on a more permanent basis.

Since 2000, there have been more than 2 million participants in Tate Modern's learning programmes and the existing spaces cannot cope with the demand.

The project is due to be completed in 2012 at an estimated cost of £215 million at 2012 prices. To date Tate has received £50 million from Government and approximately a further £25 million from other sources.