Building modern art in stone
If you want to build a home that has a sense of immortality about it, build it in stone. From the Parthenon to St Paul’s, to the humblest country cottage, it stands for solidity and authenticity. Some cities or regions have such a strong association with a particular stone that it’s almost used as a shorthand for its entire character: what would the Cotswolds be without its golden limestone? Or Glasgow without its russet red sandstone tenements?
“Stone gives a sense of quality, timelessness and permanence,” says architect Thomas Griem. “Its relative weight suggests immovability. The nature of the material, being formed over millennia, means it carries a record of where it comes from – a history displayed in its formations.”
Thanks to modern building regulations that require homes to be highly insulated, you are in fact more likely to use stone as cladding than as a loadbearing material. Architects are finding exciting ways to build using stone, merging traditional, local materials with modern design.
CaSA Architects recently completed a project on the fringes of Bath that is a refined example of a modern stone home. It combines stone in two formats: smooth ashlar blocks (large, squarecut stones), and irregular dry-walling, with a zinc-clad upper storey. The house sits very well with its honey-col- oured neighbours, yet stands out for its crisp outlines and swathes of glass. The stone acts almost like a bridge between the traditional character of the area and the modern.
The dry-stone walls have that characteristically effortless look about them, but to achieve this artless imperfection is not easy. Sample panels were made up and approved before the work began, so that there was an agreed finished look. “It is important to minimise the number of people laying stone, particularly when using walling stone,” says project architect Adrian BilesWood. “Different people can lay it slightly differently, which varies the overall appearance – similar to the variation in people’s handwriting.”
Despite the stone being locally sourced from a quarry in Tetbury, Biles-Wood says that stone is one of the most expensive commonly-used building materials, due to the cost of quarrying, cutting and transporting it, as well as the on-site labour. However, there can be creative solutions that incorporate less of it. “Sometimes clients have to make difficult decisions to balance quality and cost. This can be managed by the use of natural stone in the key areas, supplemented by alternatives such as render in the less important areas,” says Biles-Wood.
This less-is-more effect was employed by architects MawsonKerr for Shawm House, a property in Northumberland. It is mostly timber clad, but one gable end sits adjacent to an old stone wall, where a dry-stone waller was employed to create a rustic-looking facade. The wall is not a true dry stone; instead the mortar joint is set deeper, so it is less noticeable, with the gaps casting shadows that change with the time of day. Using local, vernacular materials is nearly always a winner with planning departments, and self-builders like it too – people want to use something local, but in reality there’s not much chance to do so. There’s a sustainability argument too, since true eco-builders now want their materials to have a “low embodied energy”, which means expending as little energy as possible in their manufacture and transportation.
That can definitely be said about the Jersey granite used by Hudson Architects for Le Petit Fort, which has been reclaimed from the building that stood on the site previously. The land overlooks the sea on Jersey’s west coast, and already had a long wall, built in the Twenties. Architect Anthony Hudson describes it as “a folly with battlements and arrow-slits”. Hudson’s idea was to build, at the house’s centre, a square granite tower that was envisaged as a castle keep, to complement the curtain wall.
“Granite is an interesting material. When it’s first quarried, it’s often much pinker, and it oxidises as it weathers. We wanted it to have that weathered feel, so it made sense to reuse as much as possible,” says Hudson. “As it weathers it also picks up mosses and lichens, which give it a slightly greenish tinge and add to the beauty of it.”
Architect Cassion Castle has a similar material appreciation for knapped flint, which he used for the Suffolk house that he designed for his brother. The ground floor is covered in flint, set into grey lime mortar, with a second storey of black timber.
“Up close, it’s lovely – brown, white, blue and grey. It almost feels like scales,” he says. “There’s something very enriching about engaging with a material that’s hasn’t come from a factory.”
Flint garden walls were part of the local vernacular. It was up to Castle to devise his own rules of how to lay one out.
“It’s very labour intensive, so the temptation is to spread out the flint so that the mortar joints get bigger. But the closer together it is, the nicer looking it is,” he says. “I specified the mortar gaps with the contractor, but I still had to condemn a few panels that weren’t right. It turned out that all the panels I liked were by one particular guy, so he and his mate ended up doing the rest.” A couple of square metres can be done in a day, at a cost of £250 per square metre. “It’s probably the most extravagant element of the house.”
Stone is also being used as the defining material for some incredible interiors – especially for staircases – making a bold sculptural statement.
Jamie Fobert Architects created a sweeping example with a long, sinuous balustrade in a rare silvergrey travertine, a kind of limestone found near min- eral springs, for a project in west London. It looks monolithic, carved from a single block, but was in fact installed three steps at a time, with the striated pattern of the marble closely matched to hide the joins.
Architect Amin Taha also worked with travertine to build a more compact staircase for the refurbishment of a Bayswater townhouse. With a balustrade made from spiralling brass bars running up through the building like a vortex, the staircase’s soffit, or underside, has been roughly tooled to look as if it came straight from the quarry, providing maximum contrast with the smoothly honed treads.
What’s next for stone? Taha is spearheading a movement to bring it back as a load-bearing material, using solid stone columns and lintels instead of concrete and steel to build an office block in London’s Clerkenwell. On Kent’s North Downs, Cassion Castle is working on a new house made from a stone that seems improbable as a building material. It will be made from chalk, which will be pulverised, mixed with a little water and lime, and pressed into formwork. It ticks the box for “low embodied energy”, since the chalk will be extracted on site.
“It’s chalky grassland, and we wanted to create something that felt of its place, nestled into the landscape,” says Castle.
“There are chalk buildings still around from the 19th century, but the chalk isn’t exposed on the outside, so ours will be an innovation. Moisture is the enemy, obviously, so you have to stop rising damp and have big overhangs to prevent the rain soaking in too much. But it’s totally achievable.”
Thomas Griem’s work at Berkeley Homes’ Sandringham House, main; Hudson Architects’ Le Petit Fort in Jersey, below
Amin Taha’s staircase in Bayswater
A house by Cassion Castle in Suffolk with flint and timber