Wooden Roof London House Renovation, Tsuruta Architects English Property, Architecture Photos

Wooden Roof by Tsuruta Architects, London

15 + 14 Sep 2021

Design: Tsuruta Architects

Grade II-listed house conservatory extension

Location: London, England, UK

Stephen Lawrence Prize 2021 Shortlisted

Wooden Roof design by Tsuruta Architects England UK

Photos © Ståle Eriksen

Wooden roof – text from Tsuruta Architects:

The wooden roof was constructed to form a conservatory in this north-facing London garden that has strong afternoon light from the west on sunny days. Natural light within the built environment is appreciated and desirable in northern European climates, this being where the conservatory was originally invented.

Wooden Roof London house conservatory extension

Traditionally, conservatories tend to have a pitched roof, with glazed panes creating a fall for the rainwater to run off, which reduces watermarks on the glass and maintains good visibility to the sky. However, the traditional roof pitch requires height, which was not an option at the rear of this London semi detached Grade 2 listed house.

Wooden Roof London house conservatory extension

Our solution was to create a series of higher pitches in short lengths that push rain water rapidly to the longer gentle primary valley fall. Consequently, the overall roof height was kept to a minimum, yet it has a well-drained glass surface with a deeper floor plate below.

Wooden Roof London house conservatory extension

The dia-grid geometry of the roof structure was derived simply from the existing site boundary, and helps to segment the Four Seasons glass roof into practical unit sizes. With the deep profiles within the grid, the beams cast palpable shadows of the dia-grid into the space and sometimes onto the beams themselves throughout the year, this emphasises the presence of natural light in this northern European climate.

London property conservatory extension

Once the roof was formed, the dining space below was developed in relation to the garden, which is higher than the conservatory floor level. In order to mediate this topological condition, we inserted an ’empty stage’ at table height between the garden and dining room. The primary purpose of the stage is to be ’empty’ so that the garden merges into the background within a framed view. For the occupiers, the space below the roof feels as if it is expanding into the garden.

London property conservatory extension

We took full advantage of the natural structural capacity and low thermal conductivity of wood. The entire conservatory, from the roof, to the window and door, was made from the same species of acetylated wood components, which is known for its durability and dimensional stability. From our digitally transferred design models, the wooden beams, posts and window frames were processed to within a millimeter of accuracy with a 5 axis CNC router.

London property conservatory extension

This enabled the planned roof falls to be installed correctly and easily on site which also minimised waste and off cuts. All of the cross junctions of the beams were structurally designed with no requirement of glue or any mechanical fixings (although glue was used for the ease of positioning during the assembly process).

Wooden Roof design by Tsuruta Architects England UK

Externally the wooden faces are fully exposed and charred to protect against rot and fungus decay and internally they were oiled so that it breaths. Both treatments allow the wood an extended longevity. The empty stage, adorned by a red maple tree, remains devoid of activity except for the occasional play of dappled light on the stone surface by the large European ash tree in the garden.

London property conservatory extension

Wooden Roof London

Jury Report from RIBA Stephen Lawrence Prize

The simplicity of adding a conservatory to a house provides architects with an incredible range of expressive opportunities. Wooden Roof takes this opportunity to a new level of sophistication and elegance.

Wooden Roof London house conservatory extension

Clear constraints imposed by its grade II listing – limits on the overall height and the need to remain subservient to the main building – has prompted a bespoke contemporary solution that utilises digital manufacturing techniques. The result is a uniquely crafted timber structure that draws on valuable lessons from traditional Japanese joinery.

English home conservatory extension section

The judges were without exception hugely impressed with the rigour with which the project has been carried out. The precision of the faceted glazed roof extends to the way the timber ring beam is jointed and even to how the perimeter gutter is detailed to provide a genuinely considered elevation to the upper rooms of the house.

English home conservatory extension plan

The design emphasizes timber’s expressive qualities by putting the language of carpentry at the heart of the project. It exemplifies how timber, which is intrinsically sustainable, can and should become the structural material of choice for small- and medium-scale projects and confounds assumptions that timber structures are inevitably heavy, simplistic and limiting.

Wooden Roof design by Tsuruta Architects England UK

Setting the extension partially below ground level required a meticulous negotiated section. The detailing of the external surfaces was no less carefully rendered than the roof itself. Even the placement of stone slabs within the lawn to make an outdoor seating area has the compositional skill of an artist.

Internally, the quality evident in the structural joinery of the roof runs throughout the furniture. The clarity of detailing gives a sense of repose while providing all the storage and utility that a house has to provide for its inhabitants.

Film on YouTube

This is not an uncompromising architectural statement. Although it adds visual balance, clarity and beauty to the listed house, it does so in a way that facilitates domestic life. The judges have put the project forward for the national ‘Small Project’ award.

Wooden Roof by Tsuruta Architects in London, England, UK

Wooden Roof London – Building Information

RIBA region: London
Architect practice: Tsuruta Architects Tsuruta Architects
Structural engineer: Webb and Yates
Date of completion: May 2019
Client company name: n/a
Project location: London
Contract value: Confidential
Internal area: 19.00 m²
Cost per m²: Confidential
Contractor company name: JK London Construction LTD
Digital fabrication: Tomasz Barszcz, Tsuruta Architects
Garden concept: 1moku

Photography and Video: Ståle Eriksen
Video edit: Stephen Connolly

Wooden Roof design by Tsuruta Architects England UK


Structural Engineers: Webb and Yates

Photography and video is by Ståle Eriksen.

Wooden Roof London house conservatory extension


• RIBA Regional Award
• RIBA National Award
• Stephen Lawrence Prize 2021 Shortlist

Wooden Roof London house conservatory extension

Stephen Lawrence Prize 2021 Shortlist

Wooden Roof by Tsuruta Architects, London images / information received from RIBA 140921

Founded in 2006 by Taro Tsuruta, this English architecture practice has desined a series of dramatic home transformations across London.

Phone: 020 7633 0055

Location: London, England, UK

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