Post is a $53 million boutique mixed-use development in the former post office building in Potts Point, Sydney. It features office, retail and restaurant space and was developed by Ashington.
The mid 20th-century building has three street frontages and had undergone substantial gentrification over the past 10 years. The new design of Post re-used the existing building fabric of the post office, including structural columns, floor slabs and the concrete beam ceiling systems.
The design intent was to open up the building on the ground level, creating a series of colonnades and walkways around a glazed retail centre. The original large, windowless structure includes a new façade to Macleay Street, with a five-storey glass wall and colonnade. The building also includes high performance glass and insulation, mixed mode ventilation with operable windows and automated air- conditioning, energy efficient lighting and building management including monthly reporting on energy consumption.
Around 50 per cent of the existing floors were demolished, with the addition of new floors between old floors, and the basement was demolished and excavated.
One of the most challenging aspects of the building for David Katon was the development of the Macleay Street façade. BKH worked closely with engineers, builders and manufacturers to achieve single 15m high columns with no joints.
“Dramatic full height columns were introduced with a curtaining wall glass façade behind it to provide an iconic architectural statement on Macleay Street, and to express the building’s commercial function with a backdrop of residential buildings of all periods,” he says.
The column spacing repeats the existing building’s structural grid and represents the vertical breaks in the original full brick Macleay Street façade on the same grid. The columns were made off-site by a steel fabricator and were welded in the factory and sanded down so no joints could be seen.
The columns were delivered to the site by a truck and craned into position. The crane lifted the columns over the building (around 30m in the air) and lowered them down vertically. They were then filled with concrete from the top to achieve the necessary fire rating, then touched up and painted on site. Fire engineering solutions also included fire stair wrapping around the lift shaft.
Neil Denton says the entire project was a challenge due to the nature of reusing existing buildings. “We pulled the façade, pulled the building back about 8m, and were working on three street frontages. We then extended the building out 500m on two of the faces and extended the Maclaey Street face out to the same boundary line,” he says. Another issue for him as the builder was the limited ceiling space in a large part of the areas, which required services to be moved to the walls.
The project involved three construction programs running at once — basement works, groundfloor works and the formwork, existing structure, etc. This approach saved around “three or four months”, with the entire project going through a value engineering stage, where cladding — concrete or composite panel, and other methods — were researched to create the same look.
Temporary supports were erected during construction, with Denton saying they were key to the success of the project.
“We looked at different glazing — we looked carefully at every specification,” Denton says. “ESD was a big thing because it’s an existing building. You don’t have the ability to design around ESD requirements — you just deal with what you’ve got.”
Denton believes the relationship between the architect and the builder is the key to a successful project. “We have a long-term relationship with BKH … [and] we like working with them,” he says.
“The architect was very clear on the design intent and we were able to work with that to deliver what they wanted within the budget. They did a great job, and the clarity of their intent made it easier.”
Stephanie McDonald
