An Introduction to Polystyrene Insulation
Polystyrene insulation is a type of synthetic insulation that is commonly used in Australian homes.
Polystyrene is generally used for insulation of walls, ceilings, floors and even sub-floors, and is
manufactured into sheets that fit on, or between the joists.
It is extremely durable, with an expected lifespan of 50+ years.
It is also resistant to rot, mould and corrosion. Polystyrene insulation has also been found to have some
sound insulation benefits.
What are the Different Types of Polystyrene Insulation?
Polystyrene insulation comes in two different forms: Expanded Polystyrene (EPS) and Extruded
Although both EPS and XPS are rigid, closed-cell foam insulation, there are significant differences
between the two.
Expanded Polystyrene (EPS)
EPS is constructed by taking solid beads of polystyrene, which have a small amount of gas contained
within the polystyrene.
The gas inside the beads causes the beads to expand when heat is applied (through steam) and this
creates the closed cells.
EPS is safe and non-toxic, and has the ability to be removed and re-used.
Expanded Polystyrene also is exceptionally strong and absorbs impact.
Extruded Polystyrene (XPS)
XPS is made from polystyrene crystals which are fed into an extruder, along with a blowing agent
(normally carbon dioxide).
The extruder uses high pressure to combine and then melt the materials into a viscous liquid. The liquid is
then transferred to a slot die.
As the pressure drops, the CO2 then expands and forms into foam. XPS is often more expensive due to
the more elaborate manufacturing process.