CLT extension project
Yellow extension to a period property

A playful cross-laminated timber extension

The Unknown Works team used CLT to extend a family home

By Alice Westgate |

Architect Theo Games Petrohilos and the Unknown Works team used cross-laminated timber to extend a 1950s semi-detached home in Leyton, east London.

The house belongs to software engineer Annabel Bligh, 34, and Luke Leighfield, 35, a writer, artist and musician. They moved to the four-bedroom property four years ago. The couple’s one year-old son Emmanuel was born during the project.

Theo shares the thinking behind the bright yellow extension.

Yellow CLT extension in Leyton by Unkown works

Overhead in the kitchen the structural CLT grid is left exposed and has been fitted with recessed aluminium lighting tracks. Photo: Unknown Works

What was the brief?

Annabel and Luke asked Unknown Works to reorganise the ground floor and provide better access to their outdoor space. We designed a rear extension to give them a new kitchen and dining area that opens on to the garden, plus a boxy front porch.

Both are built with cross laminated timber (CLT).

Why CLT?

The prefabricated spruce panels are sustainable, relatively inexpensive and quick to build. Once the kit was delivered to the site it went up in just four days. It’s great fun to work with, rather like using a set of huge building blocks, and has a nice simplicity to it.


Between the living and dining areas a pebbled courtyard helps the ground floor rooms feel connected to the garden. Photo: Unknown Works

Tell us about the build

The exteriors of the CLT panels were insulated with high performance Kingspan boards, then we applied render that’s painted yellow. Inside the extension the CLT is left exposed for its texture and because it has a Scandinavian look that Annabel and Luke liked.

The timber is treated with a fire-retardant paint mixed with white pigment so it keeps a lovely pale tone. The CLT was also used to make built-in seating and a large pivoting front door. We even used offcuts to handcraft a set of oversized dimmer switches.

Why paint it yellow?

Annabel and Luke wanted to be playful and we responded with something fun.

Leyton-Extension Project Unknown House

The extension has sliding doors, a door beside a small reading nook and a kitchen window with a herb garden. Stainless steel rain chains direct water to the ground. Photo: Unknown Works

How do the new spaces link to the garden?

Instead of making the ground floor one giant tunnel with a dark living room leading into the kitchen and dining area in the extension, we created a courtyard in between that’s filled with white pebbles.

It’s reached from both areas through sliding glass doors that open to link the indoor and outdoor spaces. This is a piece of landscaping at the centre of the house, and gives the living room daylight and ventilation.

How has it turned out?

Annabel and Luke are very sociable and the extension project has created their perfect party space. Walking down the street and seeing the yellow puts a smile on your face, and there’s lots more joy inside.