The Sun Rain Rooms Curved Rooftop Extension |
The Sun Rain Rooms Curved Rooftop Extension

The Sun Rain Rooms Curved Rooftop Extension

Collecting rainwater and sunshine

Isobel McKenzie
Written by –
Isobel McKenzie
on January 30th 2019
Originally from London, Isobel is enthralled by the curves and lines that make up a city. It's fascinating to see how modern skyscrapers and historic landmarks muddle together. Her Instagram feed @Isobel_McKenzie is usually full of spiral staircases and tall buildings. Can also be found on Twitter.. sometimes.

Sun Rain Rooms


At street level, you’d be hard pressed to notice anything different about this Clerkenwell home. Influenced by storytelling, nature and technical innovation, RIBA Award-winning architectural firm Tonkin Liu has created a two-story annexation and restoration of a Georgian townhouse in London. The extension serves as a studio space for the practice, as well as a home area for the founding partners’ family.


A sweeping curved roof half-covers an open patio, leaving the remaining space for rain to create a reflecting pool, harvesting the rainwater to a water tank and providing a calm outdoor area to relax. It looks retro-futuristic, yet at the same time easily plays with the gentle sloping shapes of shells and nature.

Grade II listed building with rooftop extension Tonkin Liu |
image Alex James

From the front of this Grade II-listed building, you’d have no idea about the garden’s rooftop extension. Previously the building had been divided into apartments and bedsits. Slowly accruing each level over the years, it now belongs to Tonkin Liu founders Anna Liu and Mike Tonkin to use for both domestic and studio use.


In the basement, there is a bedroom, two bathrooms, and an “enlarged plant-filled light-well.” Under the roof, a garden room offers a living space for the home and a meeting space for the studio.

Sun Rain Rooms are the incredible rooftop patio and reflecting pool extension designed by Tonkin Liu for their home and studio building |
image Edmund Sumner

In the covered outdoor space, a mirrored wall conceals a workshop, kitchen space and a potting plant area to service the greenery installed into the roof. There are a mixture of plants, specially chosen for a multi-layered urban garden spanning the rooftop, outdoor garden and hanging planters.

Curved rooftop and reflecting pool for collecting rainwater |
image Alex James

What little detail do you hope people don’t miss?

Tonkin Liu: The ingenuity of the delicate ultra-thin timber roof. It was built up in layers with 6mm thick plywood panels.


All the layers were digitally cut, arrived on site, slumped onto the former (also digitally cut), then fixed together on site. Like the nodules on mollusc shells, the roof’s circular coffers are stacked and bonded to create local strength as they join the upper and lower layers of the roof. This helped the roof structure to achieve its ultra-thinness.

Tonkin Liu's Sun Rain Rooms, a green garden rooftop |
image Edward Sumner
Tonkin Liu rooftop extension designed with sweeping curve and reflecting pool |
image Alex Peacock

With one push of a button, the water collecting in the water trough can make this patio space a reflecting pool. Water rises and joins together between the paved stones. “When it’s raining at night we love to sit on the lounge chair, turn off all the lights, turn on the shaft of light beaming from underneath the rainwater tank, and watch the droplets of rain land on the surface of the reflecting pool,” describes the Tonkin Liu team. “The ever-changing pattern of these droplets, sometimes long shafts, sometimes dispersive circles, is mesmerizing.”


On sunny days, it’s a nice place to sit outside underneath the roof, “looking back along the full length of the garden at the back of the 200 year old house, and up at the piece of London sky captured in the circular sweep of the roof.

Patio garden space rooftop extension and garden area, designed by Sun Rain Rooms |
image Alex James

The firm designed a 110mm structural shell for the roof, “an insulated stressed-skin, joined by round coffered skylights that echo the wave pattern of raindrops landing in the pool.” There are rooflights too, keeping the space bright.

Curved rooftop space with hanging planters and reflecting pool designed by Tonkin Liu |
image Edmund Sumner
Hanging plants and curved rooftop design for the Sun Rain Rooms extension |
image Edmund Sumner

What advice would you give yourself looking back on the project?

Tonkin Liu: Working with a team of people who all believed in the project. Our advice is that make sure you gather together a group of believers and kindred spirits.


This will help you achieve what may seem like a huge task. A limited budget, a confined urban site, and all the elements such as sun, rain, greenery, light, that must all come together into a seamless artistic whole.

Pantry space in Grade II listed London home |
image Alex James
Tonkin Liu Architects build rooftop extension, spiral staircase access |
image Edmund Sumner
Rounded bedroom headboard in Sun Rain Rooms extension by Tonkin Liu |
image Alex James
Bedroom space in the Sun Rain Rooms extension by Tonkin Liu Architects |
image Alex James
Tonkin Liu's bathroom space |
image Alex James

The rooftop’s curve takes inspiration from the building’s curved timber heritage. The bedroom headboard mimics the outdoor curve perfectly, separating it from the bathroom. In the basement living room, there are features like plenty of natural timber, and a warm and cozy Scandinavian aesthetic. It’s a space the firm’s founders Anna Liu and Mike Tonkin enjoy hanging out in.

Basement and living room space in Sun Rain Rooms extension by Tonkin Liu |
image Alex James
Evening rooftop view of Sun Rain Rooms by Tonkin Liu |
image Edmund Sumner

Whether safely hidden behind the patio doors watching the rain pour down, or out of the sun’s way in the curved shadows, the Sun Rain Rooms lush garden extension is a striking and enticing architectural feature. As well as wining a 2017 RIBA Award for the project, Tonkin Liu have also attained an AJ Retrofit Award and Don’t Move, Improve! award for the rooftop extension project. Bonus, at the end of the day they get to relax alongside the reflecting pool. Win!


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