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is polystyrene a good insulator

Is Polystyrene A Good Insulator?

by Martha Simmonds

Polystyrene is a kind of plastic that is used to manufacture a broad variety of goods ranging from toys and packaging to automotive and electrical components. While polystyrene foam is sometimes referred to as Styrofoam, this is a trademarked word, not a technical term.

Polystyrene is among the most widely used polymers today – but is it an effective insulator?

The short answer is yes, polystyrene is an excellent insulator. Expanded Polystyrene (EPS) or Extruded Polystyrene are terms used to describe polystyrene that has been expanded into a foam substance (XPS).

Insulation materials made of foamed polystyrene (EPS and XPS) are utilized for two primary reasons. To begin, polystyrene has high thermal resistance or barrier to heat transmission. Furthermore, polystyrene foam includes thousands of tiny air bubbles, and the air is an inefficient conductor of heat.

When inflated, polystyrene has a low heat conductivity, making it an excellent insulator. Polystyrene foam has many tiny air pockets inside its structure, which contributes significantly to its insulating qualities.

Any kind of mass insulation, regardless of the substance utilized, operates on the same concept. The objective is to infiltrate the material with as many air pockets as feasible. The more air trapped within your materials, the more efficient it is at preventing heat flow. It is possible to make a good insulator if, in addition to the tiny bubbles you generate, the material itself has strong insulating qualities, as has been shown.

Benefits of Using Polystyrene for insulation

Numerous insulating materials are available on the market, including glass wool, polyester, mineral wool, as well as rock wool. The following section discusses the benefits of polystyrene insulation, including XPS and EPS foam board insulation.

1) Polystyrene is a thermoplastic material with a strong resistance to heat.

Thousands of air pockets are trapped inside XPS and (EPS). Since polystyrene is also a very good conductor of heat, the outcome is a superb thermal insulator with high R-values.

Furthermore, XPS is often coated on at least one side with aluminum foil, which results in concurrent reflection and absorption of radiant heat. It is extremely effective at reducing both heat loss and gain when bulk and reflective insulation are used together.

2) Polystyrene insulation is very resistant to moisture.

When installing other kinds of insulation, such as glass wool, it is critical to ensure that the area in which you are working is totally dry, since retained moisture may create mold problems. Additionally, moisture may cause batts to compress, reducing their efficiency and, ultimately, their R-value.

Polystyrene insulation, on the other hand, is already compacted and allows only a very little amount of moisture to pass through, avoiding the growth of mold and guaranteeing a constant and long-lasting R-value throughout time.

3) The compressive strength of XPS and EPS is very high.

There are two types of foam insulation: open cell and closed cell. Open-cell types have been treated with inflating agents to render them extra springy and compressible. Closed-cell materials, such as XPS and EPS, are denser and have a more solid structure, making them more robust and compressible. Compression may impair a bulk insulating product’s resistance to heat flow.

4) Favorite among installers owing to its simplicity of handling

Due to the near-odorlessness of polystyrene insulation, it is a preferred option among professional installers. Unlike conventional glass wool insulation, which detaches millions of loose fibers in installation and frequently irritates exposed skin, XPS has a thick structure that makes it easier to work with. Wearing standard building site safety clothing is more than sufficient while installing XPS.

It’s worth noting that many contemporary glass wool products, such as Knauf Earthwool, are now produced in such a way that they almost completely eliminate the itch factor associated with older glass wool goods.

Styrofoam’s Physical Properties


One of the primary physical characteristics of Styrofoam is that it is thermoplastic. This implies that the substance is solid at ambient temperature but becomes liquid when heated to a certain degree.

As a liquid, Styrofoam may be molded into intricate shapes. This characteristic enables it to be used in a wide variety of industries and applications. Nowadays, this material is mostly used as insulation, packaging material, as well as a craft material.

Shock Absorber & Lightweight

The advantage of Styrofoam is its low weight. Additionally, it functions as an effective shock absorber. This is because Polystyrene is roughly 90% air. This property makes the substance particularly well-suited for use as a packaging material. Although the material is lightweight, it efficiently absorbs shock, safeguarding the product from damage.

The Insulating Properties of Styrofoam

Polystyrene products are mostly composed of air, which makes it an inefficient conductor of heat but a great convector. It compresses the air into tiny pockets, obstructing the passage of heat energy. This significantly decreases both conduction and convection, making Polystyrene an excellent insulator.

In contrast, conducting materials such as metal have low insulation properties because they permit the transfer of energy. Glass and air are also excellent insulators. Polystyrene is used to insulate wall cavities in order to keep the interiors of buildings warm. It traps air and inhibits heat transmission, thus retaining heat inside the structure.

Concerns about the environment

Unfortunately, a significant amount of polystyrene ends up in landfills due to its inability to be recycled and the lack of recognized biological agents capable of degrading it. The manufacturing process releases hazardous pollutants into the environment and utilizes non-renewable fuel.

Whereas the explanation “is polystyrene an effective insulator?” yes, one of its main disadvantages is the effect it has on the environment.

Is polystyrene an effective insulator for walls?

Polystyrene foam boards may be utilized for a variety of purposes, such as external walls, ceilings, cool rooms, and beneath concrete blocks in commercial and residential construction. When putting foam board in walls, it must be carefully cut precisely to fit snugly between the wood joists.

Utility knives may be used to cut a majority of XPS and EPS-equipped boards. Insulation made of polystyrene is intended to endure many decades before having to be changed. Polystyrene foam board insulation is one of the most lasting insulation materials available.


Polystyrene is a very effective insulator. Thermal transmission is limited by the material. Therefore, independent of the outside circumstances, a building insulated with Polystyrene will keep a pleasant temperature within.

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