Foams can be used to insulate existing walls. A small hole is drilled into either the internal or external wall. The foam is carefully poured in to fill the space between the frames.
Foams generally cost more than regular insulation, however they provide the additional advantage of being air tight, reducing the air excahnge through the surfaces coated.
CLICK HERE for contact details of foam installers.
Retro-Spec Insulation specialise in retrofitting to wall cavities using Tripolymer foam.
Urethane foam manufacturers such as Eco-Foam are also able to install urethane foam insulation. Costs for urethane foam depends on thickness applied. Rough estimate from Eco-Foam was $18m2 for Rvalue 2 insulation.
Icynene is a spray in place expandable foam which was available in Tasmania until recently.