A new Melbourne bayside residential development is testimony to the design flexibility and thermal performance of an ideal, lightweight styrene formwork system.
The styrene planks - supplied and installed by Melbourne-based ICF Contracting - were precision cut in the factory to the exact radius demanded for the ideal curved exterior and interior insitu concrete walls of the Williamstown development.
This allowed the builders to achieve a seamless, smooth facade of curved concrete in executing the architect’s vision.
The Williamstown development comprises two adjoining prestige dwellings, each of approximately 80 squares comprising basement and two upper stories.
Ari Schupak, of ICF Contracting, says his formwork systems were chosen for the project for two reasons - speed and ease of construction, and thermal performance.
“The design features a lot of curves. Brickwork would not have delivered a true curve, and conventional formwork would not have matched ours for the precision of the curvature and the speed and ease with which it was installed,” he says.
“One of the beauties of our styrene formwork system is that the planks can be left in place after the concrete is poured and simply rendered or plaster boarded over, to deliver thermal insulation. This was done on a number of the external and internal facades of the Williamstown project.”
One such example was the underground basements, where the exterior planks were left in place, treated with a waterproofing agent and backfilled with soil.
For the upper levels of both dwellings, the external walls were formed up with 70mm styrene planks on the exterior side and 50mm planks on the interior side.
On the outer facades these planks were simply rendered over and on the interior sides they were covered with plasterboard.
“By taking advantage of the thermal properties of the planks, we were able to achieve good insulation value of 4 in the external walls,” Ari Schupak says.
Another advantage of the styrene planks is that channels for electrical and plumbing services can be easily cut in, ensuring a clean, even surface for plaster boarding of internal walls.
Although sitting side by side, the two dwellings do not actually share a common party wall. Rather, each has its own 200mm concrete boundary wall, again formed up with styrene planks that were left in place to provide both thermal and acoustic insulation.
One of the dwellings has a central lift shaft running through the three levels. It was formed up with another innovative ICF product - strippable plastic planks.
A false curved wall was built directly around the rectangular lift shaft to soften its lines, again extending through all three levels. A spiral stairwell follows this curved wall, with another curved wall on the outer side of the stairs.
Both these curved walls were also formed up with the styrene planks, which were again shaped in the factory to meet the curvature of the design.
“The architect provided us with the radius of the curves, and we simply machined rectangular styrene blanks to the required curvature,” Ari Schupak says.
The ICF formwork systems are also a well known building solution for basements and projects on tight inner city building sites were buildings typically go right up to the boundary, and restricted access to the site precludes the use of precast panels or blockwork.
“In cases where you are building up to an adjoining existing wall, you can use the styrene planks as the exterior facade formwork and leave them in place,” Ari Schupak says.
“It is a simple, fast and thermally efficient solution. In fact, the insulative qualities of the product are fast making it the material of choice for architects, who want to achieve energy efficient buildings and provide clients with all the benefits that solid construction offers.”
“Concrete is already well established as a sustainable building material. When combined with the ICF system, you can further significantly reduce the environmental footprint of your building or home by better stabilising internal temperatures and reducing energy consumption for heating and cooling.”