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Lush, listed and loved

by Ruth Slavid
The listing of Gateway House in Basingstoke provides a great opportunity to revisit the thinking behind one of the earliest uses of green roofs.

In January, English Heritage (now Historic England) listed 14 post-war office buildings, a move that elicited the jokey media response that is all too common where mid 20th century architecture is involved. In fact they were an impressive crop of well-preserved buildings, designed for ways of working that have since changed but which still manage to find valuable uses.

Among these buildings was Gateway House in Basingstoke, now known as Mountbatten House.  And this building in fact had two separate listings, one for the building and the other for the roof gardens and perimeter landscape. It is this latter element that is truly extraordinary.

We tend to think of green roofs as a contemporary trope, but in fact their history is long, going back as far as the turf roofs of Viking homes. Indeed, the moniker ‘the hanging gardens of Basingstoke’ given to Gateway House is an indication of just how old the idea is. Nevertheless, in 1974 to 76, when Gateway House was built, there was no industry to support the use of green roofs – no tried and tested root barriers, no sedum mats and no real knowledge of which plants would thrive and which would not.

It is a testament to the care and thought that went into its design that the building not only attracted praise when completed but was seen as in sufficiently good and unaltered condition to justify listing 40 years later.

English Heritage gave the following reasons for the decision to list the building Grade II:

• Architectural interest: it is an unusual and distinct example of 1970s commercial office architecture by Arup Associates’ Group 2, showing innovative and good quality design and use of materials in both its exterior and interior;

• Historical interest: aside from its immediate association with the nationally important architects firm Arup Associates the building has an important historic association with the nationally renowned garden designer James Russell (the roof gardens being one of his key works). Additionally, the building’s association with Wiggins Teape, an important and well-known British paper manufacturer, adds further to its special interest;

• Intactness: its exterior has survived remarkably intact, with no later alterations, and despite some internal re-ordering, its plan form and interior, through the survival of key fixtures and fittings, retains a good degree of authenticity;

• Group value: it forms an integral part of its particularly important associated landscaping.

Much of the success is down to the landscape architect on the project, Charles Funke, who worked closely with Arup Associates on the project. Funke, who has had his own eponymous practice for 30 years, mediated between James Russell’s planting list and the architect. He had the ideal background for this job. A landscape architect, he had worked for years for planting company Craigwell House Nurseries and Flower House International, and his projects had included planting for temporary exhibitions and also work at the Royal Tournament. In both cases it was important to save weight and so he was used to working with soilless planting – a skill he had first developed during World War Two when he was charged with growing salads to feed the Eighth Army in the desert. 

Arup Associates had designed the building on a slope facing towards the south and the idea was
to make the most of the views and to allow office workers both to see the outside world and to step out into it. An article in the Arup Journal in 1979 says, ‘Efforts have been made to make pleasant outdoor areas available to all those who work in the building, on the basis both that it is sometimes desirable actually to go outside from your office, and that the knowledge that it is possible to do so banishes any feeling of being “cooped up”. So the terraces and courtyards have been extensively landscaped in such a way as to offer considerable variety of outlook from different offices on all levels. Trees, bushes, grass, paving, seats, rocks, pebbles and water have all been used. Areas of the site not occupied by the building have also been densely landscaped with semi-mature trees.’

So what exactly was Charles Funke’s involvement in this? ‘James Russell had put a collage of plants together,’ he explained. ‘I said, some are fit for purpose and some are not. I had an understanding of the micro-climate that you get on such buildings. The orientation of the terraces at between south and southwest was near ideal. There was a lot of protection from the north and the east.’ He was confident that there would be adequate water and that the soil would not freeze – the air circulating in the voids of the building would ensure that, he thought, although he admits ‘there was an element of guesswork’.

Funke knew from his experience at the Royal Tournament that the important thing was to have a lightweight soil that could hold organic material and not dry out. He based his soil on one that he had created for the Royal Tournament, incorporating Lytag, a burnt clay lightweight aggregate. For a root barrier he used an early fibreglass insulation product called CosyWrap which, he said, ‘I knew would work from previous experience’.

He asked for a 14-day flood test and, apart from some small areas around the lift shaft, did not find any leaks. The ‘flat’ roofs were all laid to falls and there was no ponding of water. And this level of attention to detail extended to the plants as well. ‘We took great care with the plant material,’ Funke said. ‘If I wasn’t satisfied with the structure of a plant I wouldn’t buy it.’ 

The immediate result was a wealth of healthy looking plants – and this health has been maintained. Some trees have been taken out and replaced as they reached maturity. Funke was insistent however that the roots must be left in situ as pulling them up would have destroyed the integrity of the root barrier.

There have been other changes, in particular the introduction of more flowering plants. Over the years, members of Funke’s team have visited regularly. The building is less generally accessible than it was, since Wiggins Teape left it and it is now occupied by a company involved in the defence business, with concomitant security concerns. But there have been visits, not least by English Heritage for the listing, and just a few years ago Funke flew over it in his plane and was impressed by what he saw.

Would he do anything differently? Yes, but not because he regrets anything. ‘If we had the
knowledge we had today, we would have had a different regime,’ he says. Plants survive out of doors today which were previously not seen as hardy, largely due to the way that they are reared
in nurseries. Because of this and the form of its building, Gateway/Mountbatten House is definitely of its time – but that is what makes it worthy of listing. And, as a working environment with its generous access to well-considered outside space, it is far more civilised than many offices designed today.

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