“Create something fabulous.”
These three words – laid bare, and no more and no less complex – sum up the surprisingly simple brief for the Napoleon Street House alterations and additions project.
Without needing to express what he wanted in too many words, therefore unlocking a whole host of design possibilities, the client approached Maria Gigney Architects (MGA) to renovate an existing 1890’s cottage, and build an adjacent small concrete house on a steep waterfront site in Battery Point, Tasmania.
“This is the second project we have completed for our most fearless male client,” says Kate Symons of MGA, the same firm that designed an award-winning house for the client a decade ago.
“He provided a minimum brief then stood back to allow us to create the most sustainable building achievable.”
However, the planning and design process did not run quite as smoothly. While the original brief commissioned the creation of two separate houses, this was quickly challenged by contentious heritage constraints that rule Battery Point, a ‘hyper-conservative’ suburb with a predominance of historic building mimicry in new structures.
The eventual Planning Appeal and success led to the decision to set up the second new structure as an addition to the existing dilapidated cottage.
For the architects, this modified brief did not necessarily hinder their designs. Contrastingly, it presented an opportunity to explore material reuse and reinterpretation.
What results is a building with a minimalist aesthetic, featuring a restrained palette of concrete, timber and glass. Supporting this outlook are various initiatives which help to create what is in essence more than just an elegant structure – a sustainable home.
Much of the existing cottage has been retained in its original form, including the timber flooring, weatherboard cladding and traditional veranda decoration. A central compact kitchen area, along with stairs leading to the lower floor bedroom and a bathroom jutting out to the side of the cottage have been inserted to add greater flexibility to these areas.
Here, the predominant materials used are precast concrete panels and Celery Top Pine internal wall cladding custom run by Custom Cabinets. This is reinforced by Tasmanian Oak, a readily available native plantation timber and form of Eucalyptus, which was utilised for much of the built-in cabinetry, new flooring and stairs, and all of the free-standing furniture.
Timber: The Good Wood
Although timber is one of the stand-out materials, no proprietary timber products were used on this substantially ‘bespoke’ project.
According to Symons, the use of celery top pine cladding as the major structural and cladding component was client generated, and architect supported, chosen for its longevity, aesthetic appeal and salvaging potential.
“We were lucky to locate a FSC certified merchant in the Hobart area that already held a supply of logs. We were thus able to design the celery top beams and columns, visible in the completed house to suit the available lengths of the unmilled logs,” she said.
Locating the celery top pine felled logs before the project commenced was essential for the architects, who wanted a sustainably-sourced material.
The entire log set, which included approximately $100,000 worth of felled logs, was purchased and milled by the merchant on site. For six months, the racked rough sawn timber was stored before being trucked to the city, where it was racked for another eight months.
Most of it was then transported to the joiner in the city for preparation of the cladding.
“[The timber] was not totally dry once installed in the building, and has continued to develop a patina as it dries and ages,” says Maria Gigney, principal and director of MGA.
“We accepted that some of it was not first grade, thus some cracks and splits are evident in the building where they will not compromise water tightness.”
The off cuts of the logs were used for areas with less exposure to view, as well as for fascias, trims and joinery. This has ensured minimal waste of the material.
In the roofs, structural and light steel framing was avoided where possible. While this design was structurally achieved, the building process was substantially delayed due to the time it took for the green timber to dry.
As a result, two steel roof beams were installed over the main living area, and clad in the solid celery top beams. The entire roof purlin system is hardwood.
Timber was a crucial ingredient in ensuring that the building would be well insulated. The desire for 'floating’ concrete floor slabs with visible edges gave rise to the use of a timber framed curtain wall glazing system, which forms an insulation envelope around the outer face of the concrete structure.
The thermal efficiency of the external wall design also relies on timber to create 'reverse veneer' components. Wall elements requiring services were built with a 150 concrete skin inside the building, which acts as a thermal mass element.
This concrete skin is protected externally via a wall cavity and a stud-framed, insulated and celery top-clad outer skin.
Together with thermal breaks between indoor and outdoor floors, the window system ensures no part of the internal concrete structure is in contact with the outdoor air. Western Red Cedar was chosen for the window frames, primarily for its workability in lieu of celery top.
These wall elements, including the window system, run across two storeys, completing the insulation skin around the building.
“Our desire as architects was to complement the higher embodied energy concrete with a low embodied energy material locally sourced, namely timber,” explains Symons, reflecting on the fact that their request to use alternative curing compounds in the mix, given the extensive use of concrete on the building, sadly fell on deaf ears.
“Ultimately we won the moral battle but lost the practical war, and standard concrete was utilised. To offset this loss, we increased the amount of timber in the building.”
For the Napoleon Street House, challenges have been overcome with innovative and thoughtful solutions. The use of organic timber, which will age gracefully, plays a big part in allowing the building to nestle into its site, so that it eventually takes its place in the conservation hierarchy of Tasmania.
Intergrain ‘Ultra Clear’ Interior: water-based finishing product for timber floors
Intergrain ‘Ultra Clear’ Interior, a tough, water-based interior clear timber finish, was used on all timber flooring in the Napoleon Street House.
Incorporating UV absorbers, Ultra Clear Interior provides protection against the colour change of timbers by shielding against the UV rays. It also resists abrasion, water and most household chemicals, is low odour and unlike oil-based coatings, will not yellow.
Easy to apply and fast drying, which is important for renovations, Ultra Clear Interior allows several coats to be applied in one day, either with a brush, applicator or spray.
The product is available in gloss and satin, and may be tinted to a selection of contemporary colours. It can be used on all interior timber, including doors, windows, furniture and joinery.
Features:
• Water based
• Tintable in a range of contempory colours
• Low odour
• Sprayable
Benefits:
• Non yellowing
• Tough and hard wearing
• Fast drying and easy clean up
• Can tint to be a one step stain and varnish product
To find out more about this product or contact Intergrain, please click HERE or visit www.infolink.com.au/c/Intergrain-Timber-Finishes.
Photography by Jason Busch
