XPS, EPS, Polyiso, Mineral wool, what are they?

If there is anyone, Australians consumers are key people who should be familiar with house insulation materials. Let's discuss the several kinds of rigid insulations that are used for providing continuous insulation and better thermal comfort for your homes.

The Monk

7/11/20242 min read

white concrete building
white concrete building

Welcome back Aussie home owners, builder and owner builders, if you are lead here because you are considering building a new home that requires better insulation - you are in the right place.

Rigid insulations are going to be key materials of the future for a comfortable living environment. So, you are in the right direction if you are exploring for your home or for your next project.

They provide a great choice to provide a continuous insulation outside of the frame and act like a good blanket / down jacket for your home and the living space. It helps to keep it at a consistent temperature leading to a thermally comfortable living space.

The materials used can be largely classified in to Petroleum derived, Chemical and Natural. We will see more of that in the table below.

Expanded Polystyrene (EPS): This is formed as the name suggests by expanding the polystyrene materials. It is very porous and brittle is nature. It is more akin to the Thermocol used in packaging. Due to the porous nature of it, water will eventually seep in it - leading to efficiency loss. They are also not not very good in dealing with Termite for the same reason. This can be used only on wall or ceiling where

Extruded Polystyrene (XPS): It's the same polystyrene except this time squeezed through to get a compressed version of the EPS. This means less porous version that can be used to insulate under the slab.

Polyisocyanurate (Polyiso): This one is referred to as PIR, polyol, or ISO. it is a thermoset plastic typically produced as a foam. This material is largely used in cold storage conditioners and freezers to insulate the compartment. It is one of those materials that has good insulation for its size, but generally considered expensive.

Polyurethene (PUR): Made from isocyanate and polyol to form a rigid foam material. They are generally good at moisture resistance. They having a higher thermal resistance compared to the XPS foams, but fails to beat the Phenolic foam materials.

Phenolic foam: While all the above this are in some form a derivative of Petroleum. This one is a pure chemical product. However, this is pretty fantastic with its insulation capabilities. Quite good with fire and smoke resistance and impressive insulation every inch. It's not great with load bearing - generally comes with about 40 kpa and upwards.

Mineral wool: The rock wool material, highly fire resistant, serves very good for sound proofing than insulation. The biggest advantage this has is its a naturally occurring material making it environmentally friendly. For a good insulation they have to be thicker than some of the other materials and tend to be harder to hold together and install.

Cork insulation: Another naturally occurring material hence environmentally friendly. Frequently used for sound insulation. Similar challenges to Mineral wool. It has to be very thick to get the same outcome as XPS, PUR or Phenolic foam.

If you are keen to understand the material source, this table summaries to help you take an informed choice.

The following table summarises them.