Polystyrene Insulation

What is a Polystyrene Insulation?

Polystyrene Insulation

Polystyrene Insulation is a material that is commonly used in construction projects to insulate against heat loss. It is made from a variety of different chemicals and can be either rigid or flexible.

Polystyrene insulation is an effective way to keep your home or office warm in the winter and cool in the summer. There are two main types of polystyrene insulation: expanded and extruded.

Expanded polystyrene (EPS) is made by adding air to molten polystyrene, which makes it light and spongy. Extruded polystyrene (XPS) is made by forcing molten polystyrene through a die, which creates long, thin sheets. Both types of insulation have their own advantages and disadvantages.

What Type of Insulation is Polystyrene?

Polystyrene is a closed-cell insulation, a synthetic resin that was first used to produce Styrofoam as a packaging material. It has been found to be safe and effective as an insulator for energy, sound, and other applications.
In home insulation, it is commonly used as loose fill or rigid foam insulation. Polystyrene insulation is a high-density form of plastic foam.
Polystyrene Insulation
The product’s unique cellular structure, which gives it its insulating properties, also gives it a very low density and incredible strength to weight ratio. This makes the material perfect for applications that require insulation, yet need to be lightweight and strong.
Polystyrene insulation is manufactured through an extrusion process that involves heating powdered (expanded) polystyrene until it melts. The melted liquid plastic is forced through die openings to form long strands or “chops” of solid polystyrene foam. These chops are then cut into desired lengths and cooled.

Is Polystyrene a Good House Insulator?

Polystyrene is an excellent insulator because it is a good conductor of heat. That is, it transfers heat quickly. Its low density and high strength-to-weight ratio also make it an ideal insulation material.

In fact, polystyrene insulation has an R-value (a measure of the material’s resistance to heat flow) of R-5 per inch, making it among the highest-rated insulation materials available.


It is, however, susceptible to moisture damage. Over time, water can saturate polystyrene insulation and cause it to lose its insulating properties. The problem may be exacerbated in wall assemblies if a vapor retarder isn’t installed behind the drywall.

Polystyrene insulation can reflect up to 97% of radiant energy, making it an effective thermal barrier. It is also a good moisture and mold barrier. Polystyrene insulation helps keep homes warm in the winter and cool in the summer.

How To Install Polystyrene Insulation?

The best way to install polystyrene insulation is to have a professional do it for you. However, if you are comfortable doing it yourself, here are some general instructions:

  • Measure the area that you want to insulate and have enough insulation to cover it.
  • Cut the insulation to the desired size and shape with a sharp knife or scissors.
  • Install the insulation horizontally.
  • If possible, install a vapor barrier over the insulation to protect it from moisture damage.
  • Apply an adhesive or sealant around electrical boxes or pipes for increased protection against moisture. You can also staple fiberglass batts to these areas so that the batts completely fill the area.
  • Cover any exposed edges with insulation or caulk. You can also use foam board to cover exposed gaps between studs and electrical boxes.
  • If desired, paint the wall after your insulation is installed to match other walls in your house.
  • Finally, check the insulation for any moisture damage. If there is any visible moisture, remove it or allow it to dry before re-insulating.

How Do You Fix Polystyrene Insulation On Walls?

If polystyrene insulation is hanging loose from your attic, crawl space or exterior walls, then you may need to add additional fasteners. Fasteners can help keep the insulation in place between framing members or studs.
You can screw if necessary a patch of plywood over the insulation and felt paper where the insulation is missing or falling out. Then, staple the edges of the plywood patch to the framing members. Finally, re-insulate the area with fiberglass, cellulose, or foam insulation.
The best way to fix polystyrene insulation on walls is to install a new layer of insulation over the top of the old insulation. You can also use spray foam insulation, which will fill in any gaps or holes in the old insulation and create an airtight seal.
In some cases, you may be able to just remove the damaged area of insulation and repair the wall. If the insulation is only slightly damaged, remove just enough material to fix the problem. Each type of insulation is different, so check the manufacturer’s instructions before you begin.
If you have polystyrene insulation in your wall, it’s a good idea to have a professional check it for moisture damage. Moisture can cause the insulation to lose its thermal resistance and increase the risk of fire.

Is Polystyrene Safe for Insulation?

Polystyrene insulation, when installed correctly, is safe for insulation. However, polystyrene does have its disadvantages. While it can be an effective thermal and moisture barrier, some people are concerned about whether the material is safe to use in homes or commercial properties.

There are a few things you can do to make sure your polystyrene insulation is safe. First, make sure you have a professional install it for you rather than doing it yourself.

If your insulation is loose, missing, or damaged in any way, call a professional to handle the problem. Inspect your polystyrene insulation regularly for signs of dampness or mold growth. If you notice these signs, contact a professional immediately.

Make sure your polystyrene insulation has a vapor barrier between it and any surrounding materials. Moisture buildup can cause the insulation to lose its thermal resistance and increase the risk of fire.

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