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Choosing the Best Shipping Container Insulation

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Choosing the best insulation for your modified shipping container can be daunting, considering how many different types of insulation are available. Proper insulation ensures your container has a comfortable working environment despite outdoor weather conditions. Poor insulation can let heat or cold into your container, which can be uncomfortable, or people or damage items stored inside.

Not only does proper insulation help control the temperature of your modified shipping container, but it helps keep energy costs low. Which insulation should you choose for your cargo container? In this article, we’ll look at the best shipping container insulation and the most common types used for modifications.

Shipping container insulation options from Southwest Mobile Storage.
One of the most common modification requests we get at Southwest Mobile Storage is to add insulation to a container. In this post, we highlight the best types of shipping container insulation.

Types of Shipping Container Insulation

There are many different types of insulation, but they all fall into four specific categories. You rate insulation by its R-value. The R-value is the resistance level to the heat that the insulation is blocking. Moreover, the higher the R-value, the better the prevention of heat energy transmission. Consequently, the better the insulation, the better the temperature inside your container.

The four most common container insulation types are:

  1. Blanket insulation
  2. Loose-fill insulation
  3. Expanded foam insulation
  4. Spray foam insulation

Below, we discuss each one in depth.

1. Blanket Insulation in Shipping Containers

Blankets are ideal for shipping container insulation in office and living spaces, making them a popular choice. Fluffy and compressible blanket insulation uses long fibers, a low-cost option that is easy to install.

Varieties of this type of insulation include:

  • Fiberglass: Fiberglass is the most common type of wall insulation. You make it from superheated sand or recycled spun glass turned into thin fibers.
  • Slag, Mineral and Rock Wool: This type of insulation is made from spun minerals, ceramics or slag.
  • Sheep’s Wool: Just like it sounds, it’s made by shearing wool from sheep. Sheep’s wool is safe to touch, and you can be used safely by even at-home DIYers.
  • Cotton: Cotton is typically made from recycled denim or blue jeans, resulting in a blue-tinted color. It is often more expensive than other types of insulation.

2. Loose-Fill Insulation

Loose-fill shipping container insulation is suitable for existing areas that have been finished, oddly shaped spaces and around barriers. This type of insulation is common in attic areas, where insulation needs to be added or replaced, but it can also work in modified cargo containers. It’s installed either through a blower or by pouring the insulation.

There are three subtypes of loose-fill insulation:

  • Cellulose: You make cellulose from recycled paper or paper products that have been shredded and blown in with a machine.
  • Fiberglass: Loose-fill fiberglass is like blanket fiberglass but is less dense. It is also not as tightly bound.
  • Vermiculite or Perlite: You typically add Vermiculite and Perlite to wall cavities. You use perlite for better drainage and aeration, and vermiculite if you need more moisture retention.
Insulation lines a modified storage container.
Proper insulation keeps your container at a comfortable working environment despite the weather conditions outside.

3. Expanded Foam Insulation in Shipping Containers

Expanded foam is a popular shipping container insulation choice. In most cases, it usually has the highest R-value. This type of foam is created offsite and placed into boards and panels sized for differing wall heights. It is also self-supporting. Particularly, you can glue or attach expanded foam insulation to studs into a container wall.

Types of expanded foam include:

  • Open-Cell Polyurethane: Open-Cell Polyurethane is thin and filled with air, giving the insulation a spongy texture. It has a lower R-value than its closed-cell counterpart.
  • Closed-Cell Polyurethane: Closed-Cell Polyurethane uses a blowing agent that fills tiny, microscopic cells with a heat-conduction gas, thus increasing the R-value.
  • Extruded Polystyrene: Extruded Polystyrene, or EPS, comprises tiny, fused plastic beads. (Similar to the foam used in modern disposable coffee cups.)
  • Expanded Polystyrene: Sometimes called XPS, this foam starts as a molten material but is pressed into sheets.
  • Polyisocyanurate: Often referred to as Polyiso, this foam is similar to polyurethane but markedly more rigid.

4. Spray Foam Insulation

Spray foam insulation for a shipping container is a solid choice, and it’s the most frequently applied form of shipping container insulation. It applies and solidifies quickly and can fill areas that might be difficult to insulate another way. Upon exiting the applicator, the insulating foam will expand 30-60 times to form a tight seal. You can use foam for equipment enclosures that are temperature sensitive. Consequently, containers used for mobile switch rooms, generator systems and labs usually have this type of insulation.

Types of spray foam insulation include:

  • Open-Cell Spray Polyurethane: Open-Cell Spray is a less desirable spray foam insulation type because it has a lower R-value.
  • Closed-Cell Spray Polyurethane: The most common shipping container insulation. It has a significantly high R-value and is good at controlling moisture.
  • Damp Spray Cellulose: Damp Spray Cellulose is made from recycled paper products.
  • Cementitious Foam: Cementitious Foam is a light mixture of natural minerals, water and air, like concrete. Consequently, it’s eco-friendly, non-toxic and non-flammable.

Open-cell and closed-cell spray polyurethane are expanding spray foams, but damp spray cellulose and cementitious foam are non-expanding. Expanding spray foam means the insulation expands to fill the area, while non-expanding means the material will be packed to fill the space.

What We Use at Southwest Mobile Storage

At Southwest Mobile Storage, we use insulation for containers in our rental fleet, and custom-modified containers. The most common insulation modifications we add are Polyisocyanurate (Polyiso), Expanded Polystyrene (XPS) and spray foam insulation. We use these because they work well inside shipping containers. Furthermore, they have high R-values and provide a solid seal, meaning there’ll be fewer variations in container temperature.

If you need a container outfitted with high-quality insulation to keep temperatures manageable, speak with an experienced container representative today. We can help you find the perfect container for your project.


You can combine different types of insulation depending on how you use your containers. Shipping container insulation is essential for temperature regulation and can mean all the difference in a container you know you’ll spend a lot of time in. At Southwest Mobile Storage, we have the experience to ensure that all our insulation jobs have a high-quality standard.

Contact us today for a free quote on shipping container rentals, sales and modifications. No matter what you need, we can provide you with a container that will help you focus less on your storage problems and more on the tasks that are important to you.

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