The Cut-away Roof House is an addition to a semi-detached interwar house on Sydney's lower north shore. Sited in an undulating suburban landscape of tile and tin roofs, the project is a contemporary timber clad two storey addition. The original semi-detached house is left intact while the rear addition comprises an unconventional pitched-roof form. A large section is cut-away from the roof bringing light deep into the house, leaving a simple C-shaped plan with a courtyard in the middle. The roof and walls are clad entirely with Responsible Wood (formerly AFS) certified north coast mixed hardwood timbers, designed to operate as a ventilated facade with excellent thermal performance, above and beyond conventional residential construction methods. The design for the Cut-Away Roof house was to build efficient spaces tailored to the needs of a growing family, but without any excess or a substantially larger footprint. By keeping each of the new spaces trim, the project’s size was kept to modest ambitions, resulting in an overall saving in carbon footprint of materials and of energy consumption.
The courtyard has been ‘cut-away’ from the roof form of the house, is carefully designed to optimize solar access, providing passive heating and cooling the thermal mass contained in the concrete floor and recycled brick walls of the interior. The bricks salvaged during the demolition, were cleaned and re used in-situ.
Additionally, natural cross ventilation has been optimized to provide to all spaces of both the new and existing house with clear ventilation paths. This was achieved by repositioning the front door of the existing house and by the inclusion of the courtyard.
The structure of the addition comprises an efficient and renewable conventional timber stud (pine) framing with the minimal addition of steel required to bolster the structure around the courtyard and steel window reveals.
The project brief was highly focused on sustainable building at all stages of the project. Using locally sourced, certified timber was particularly important to achieving sustainability visions shared by the client and architect.
Using an engineered timber solution for the roof framing, allowed large open spans to living areas, while supporting the additional load of the timber-clad roof. This was achieved using LVLs.
The hardwood roof and wall cladding were selected to allow for long spans between fixings and the most efficient use of material, reducing both milling and installation time.
Cladding the roof and wall in the same timber profile creates a distinctive aesthetic outcome that also highly functional in improving the buildings thermal performance.
The living dining and kitchen spaces are arranged around the courtyard on the ground floor, while the bedroom looks over the roof to the garden beyond.
Kauri Pine timber flooring salvaged from the demolition has been recycled and used in the construction of the new stairs. Recycled timbers have the history of the house written into the character of the finish. The old lean-to of the house had passed its useable life, but the Kauri pine timber floor had plenty of life left in it and found a new use in the construction of the stairs. Kauri pine offers a beautiful, soft feel under bare feet and a warm honey tone to contrast the concrete ground floor.
Timbers used in this case study:
100x19 Hardwood Decking, Spotted Gum
45mm Hardwood Timber Battens, North Coast mixed hardwood
Machine Graded pine bearer and joist system
Finger Jointed pine
Recycled Kauri Pine