The Seed House is a custom-built sustainable home situated on a sloping site in Castlecrag on Sydney’s North Shore.

Owners James and Susie Fitzpatrick sought a home that accentuated the natural sloping landscape of the block, using seed pods found on the property as inspiration.

The concept and namesake of the home are derived from the form of a seed pod. The home is designed as a series of linked pods divided into functions, which can be opened or closed in a flexible arrangement, depending on the time of day and usage.

This stunning 658m² house designed by Fitzpatrick + Partners was crowned the overall winner of the Australian Timber Design Awards 2019, taking over eight years to come into fruition, including a design period of three years and more than 400 drawings.

Purposefully built to accentuate the natural landscape, the design aims to link the outdoors with the indoor spaces with no restrictions to the view while maximising privacy. The surrounding nature also informed the material palette of timber, steel, concrete, and stone, with every material and finish selected on the basis of criteria such as environmental performance, and the ability to provide a raw, natural aesthetic.

Responding to the owners’ desire for a natural solution on a sloping site, XLam worked with project stakeholders to deliver an intricate, functional design using cross laminated timber (CLT) in conjunction with traditional materials.

XLAM CLT panels and glulam beams were used to form the structure of the interconnected, cantilevered pods that make up the home. In addition to meeting the aesthetics of the project, the use of CLT was also paramount to the architectural vision and overcoming the restrictions presented by the sloping site. The lightweight quality of CLT and glulam allowed for a reduction in foundation loads and distribution requirements, which in turn permitted more freedom on a sloping site than typical materials, such as steel and concrete.

Structural System

Sitting harmoniously within the bushland surrounds, The Seed House is a bold celebration of mass timber used in a conventional build, featuring CLT and native timbers, natural stone, glass, and black steel.

Built predominately from XLam CLT and glulam beams, mass timber forms the structural frames, cantilevered pods, as well as the spectacular spiral staircase, which elegantly winds down three floors. The CLT structure has extravagant cantilevers exposed internally, with all exposed CLT elements containing hidden wall to floor connections.

Not unlike the CLT panels used throughout the home, the spiral staircase is made of CLT too, put together at XLam’s plant in New Zealand before being shipped to site. To achieve the necessary stiffness and stability, the treads were fitted individually and threaded over a six-metre structural steel tube member. As individual treads were fitted, each one had to be screwed into place using hidden screw locations.

The strength of the house is largely reliant on the portal frames formed between the CLT floors and walls. The side walls wrapping the CLT cantilevered pods use both the longitudinal layer direction and the transverse layer direction, acting as deep beams to cantilever off steel portal frames. The kitchen is supported by a highly architecturally refined roof truss with a top chord of composite CLT and steel.


By working alongside the architect and builder, XLam was not only able to create the owners’ dream of a sustainable, healthy, and natural ‘forever home’, but also saw The Seed House being recognised as the overall winner of the Australian Timber Design Awards 2019.

Project Details

Project: The Seed House

Client: James and Susie Fitzpatrick

Architect: Fitzpatrick + Partners

Structural Engineer: TTW

Head Contractor: David Campbell Building

Location: Castlecrag, Sydney North Shore, New South Wales, Australia

Building Methodology: Conventional Construction (CLT + Steel & Concrete)