By Rowan Moore
Architects Anna Liu and Mike Tonkin have spent 12 years on an extension that lets the weather straight into their Georgian townhouse. The result is hard not to love – especially on a rainy day
When it starts raining on the slate roof of the Grade II-listed, late Georgian north London house where the architects Anna Liu and Mike Tonkin have their home and office, it gathers in a black downpipe on the rear wall. This is normal. What happens next is not. Before it gets to the bottom, like a stunt plane exiting a death dive, the pipe turns, curves and then swoops into a more shallow descent, then goes up a bit, then down again, before terminating in a non-figurative gargoyle about two metres off the ground, from which the rainwater, after a delay while it gathers enough pressure to push itself through the elaborate pipage, then gushes.
Which turns out to be only one move of several in an architectural rain dance. The gargoyle discharges into a long black steel trough that, if a switch is flicked, then overflows via concealed pipework in such a way that water starts rising through the joints between dark granite paving in a small courtyard. Should it be night-time, horizontal lasers can be switched on, which capture drops with illumination as they fall and bounce. If it's day and the sun comes out, rippling light will reflect off the wet paviours, bouncing around surrounding surfaces of glass, mirror and whiteness. All this irrigation and solar energy eventually manifests itself as vigorous vegetation, a touch exotic and tropical, some of it growing out of the planted roof that partially encircles the court.