Many of us, whether you are a builder, architect or simply someone looking to complete a DIY project in your home, seem to be looking for the answer to a commonly asked question on whether a well-known product, polystyrene, is a good insulator.
This therefore deserves exploring. In this blog, we will talk about the differences between the two types of polystyrene, their benefits and uses.
Extruded and Expanded Polystyrene
There are two main types of polystyrene insulation, expanded polystyrene (EPS) and extruded polystyrene (XPS). Let’s take a moment to highlight the main difference between the two.
Expanded Polystyrene (EPS)
Expanded polystyrene insulation is a lightweight insulation, made up of polystyrene foam beads, with lots of small air pockets. Air is a poor heat conductor and since polystyrene has a high thermal resistance itself, it’s very effective at preventing heat transfer.
Expanded polystyrene foam provides great thermal insulation in numerous applications, such as building walls, roofing, and cold storage facilities. Polystyrene insulation is inert, durable, and resistant to water damage.
Extruded Polystyrene (XPS)
The real difference between extruded polystyrene and expanded polystyrene is in the way they are manufactured. The different processes mean that they both have varying levels of performance.
Expanded polystyrene is manufactured by expanding beads in a mold, using heat and pressure to fuse the beads together. They are then molded into large blocks that are subsequently cut into sheets or alternative sheets by hot wire machines.
Whereas extruded polystyrene is manufactured in a continuous extrusion process, whereby plastic resin, other ingredients, and a blowing agent are melted together. This type of polystyrene is effective form of insulation for areas exposed to higher levels of water.
Expanded polystyrene absorbs more water than extruded polystyrene, resulting in reduced performance and a lower R-value.
Did you know? Dyson Energy Services can laminate any insulation to any surface using our purpose build spray booth. Our hot wire machine is an auto slicer and dicer, capable of cutting polystyrene blocks – tailoring a bespoke solution to your requirements.
How effective is polystyrene insulation?
Polystyrene is a great thermal insulator and can achieve excellent R value ratings at a given thickness for expanded polystyrene, and even higher ratings for extruded polystyrene. Extruded polystyrene is more effective due to its dense structure and excellent moisture resistance. Expanded polystyrene will soak up moisture, and this can cause degradation in the R value so if you are using this type of polystyrene, it’s vital to have it protected at all times by a vapor barrier.
The more commonly used vapor barriers include various grades of polythene, as they are cost-effective and efficient.
Is polystyrene a vapor barrier?
A vapor barrier is any material used for damp proofing, that resists diffusion of moisture through the wall, floor, ceiling, or roof of buildings to prevent condensation.
The question is, is polystyrene a vapor barrier? Extruded closed-cell polystyrene can be used as a vapor barrier. However, we do not recommend expanded polystyrene to be used as a vapor barrier, as it can degrade in water.
How much soundproofing does polystyrene insulation provide?
Both expanded and extruded polystyrene are not sound-proofing insulation but are purely designed to be used for thermal insulation purposes.
Can I use polystyrene for internal wall insulation?
Polystyrene is a popular insulation material for external insulation, rather than internal.
Rigid foam boards of insulation and mineral wools are used more widely for internal wall insulation.
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