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Insulation Materials and When to Use Them

Find the right solution for your project to meet design performance, specifications and building code requirements. White Cap has the solutions to meet all your project needs from thermal to fire requirements.

There are five types of insulation that we will cover in this article:

  • Extruded polystyrene (XPS)
  • Expanded polystyrene (EPS)
  • Polyisocyanurate Insulation (Polyiso)
  • Mineral wool
  • Spray foam 

One of the most important characteristics of insulation is the R-value. The R-value measures the resistance to heat flow. The higher the R-value, the greater the insulating power. It's important to mention that a product's resistance to heat doesn't always correlate to its thickness, weight, or appearance.

The three most common types of board insulations are XPS, EPS, and Polyiso. They are similar, but each has different features and benefits.

Extruded Polystyrene (XPS)

XPS is manufactured with a continuous extrusion process that results in a closed cell foam insulation with a low perm rating. Materials with a lower perm rating slow the movement of water vapor. As a result, these materials are considered vapor retarders. XPS is manufactured with an unfaced or faced option with a variety of plastic materials. It's important to remember that XPS is an effective vapor retarder, but not a vapor barrier..

Features and Benefits:
  • Designed for use as wall sheathing, basement, foundation, and roof insulation
  • R-value 5.0 Per inch, on average
  • Semipermeable
  • Moisture resistant
  • Some products have been formulated with low Global Warming Potential blowing agents
  • Long service life
  • Available in multiple sizes and thicknesses
Dupont Styrofoam Cavity Mate1
Exceptional moisture resistance is one of the top benefits of XPS, with some of the brands making XPS that is as much as 13 times more resistant to water compared to some other insulating materials

XPS is easy to install. It is important to be careful with how the insulation is installed (that’s true no matter what type of insulation you are installing) to ensure that it retains all the other primary benefits.

Sustainability is something that has become increasingly important. XPS and other spray polyurethane foams uses hydrochlorofluorocarbons (HCFCs) as the blowing agent, which has a high global warming potential.

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SKU#: 595270290

Expanded Polystyrene (EPS)

Expanded Polystyrene (EPS) insulation is made from the same polystyrene resin base as XPS, but the process to make it is different.

EPS is manufactured by expanding spherical beads in a mold and then using heat and pressure to fuse the beads together. During production, the blowing agents move quickly through the beads, leaving thousands of tiny cells that are full of air. This allows air and moisture to move through the material more easily. EPS insulation is about 2% plastic, and 98% air trapped within the plastic. Less material is required to make EPS. On average, EPS has an R-value of 3.6 per inch of thickness.

Features and Benefits:

  • Designed for use as wall sheathing, basement, foundation, and roof insulation
  • R-value 3.6 – 4.0 per inch
  • Semipermeable to vapor
  • Moisture resistant
  • Recyclable
  • Long-Term Thermal Resistance, time-weighted average of the foam’s R-value
  • No CFCs, HFCs and HCFCs in the production process
  • Available in multiple thicknesses 

EPS is a greener choice, it doesn’t contain HCFs. It’s environmentally friendly production, it is often preferred for insulating building foundations and exteriors, it’s also a good choice for wall cavity insulation.

It comes in many different forms, such as slabs or sheets, it can be customized to better meet the needs of different projects. This makes it ideal for difficult spaces or areas that are shaped in a way that makes them harder to cover, unlike other types of insulation.

EPS without film facers has a perm rating (the measure of a product’s ability to let water vapor pass through) of up to 5.0, a higher perm rating allows vapor to escape to the outside, reducing the potential for moisture damage.

Ultimately, it is the customizability of the insulation that makes it so popular. It isn’t just that it comes in different shapes, EPS also has different thicknesses, so it can be customized based on the installation. For example, you might want a thicker insulation to protect an area from the outside environment or to add sound attenuation.

EPS can offer savings on labor costs because it comes in different forms, including composite, laminated, and hybrid products. This allows builders to combine multiple insulation products to meet different needs (further contributing to its versatility and customizability). This allows you to install EPS with other assembly components all at one time.

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Polyisocyanurate Insulation (Polyiso)

Polyiso is a high-performance, rigid foam board insulation solution known for its versatility. Polyiso is commonly used as a continuous insulation (CI) for roofs, ceilings and walls, and specialty applications for commercial and residential building projects.

Features and Benefits:

  • Designed for use as wall sheathing, basement, and roof insulation
  • R-value 5.7 - 6.5 per inch
  • Vapor impermeable
  • Excellent fire test performance
  • Moisture resistant
  • Long service life
  • Zero ozone-depletion potential and negligible global-warming potential6
  • Available in multiple thicknesses 

Given its various uses, polyisocyanurate is designed to have exceptional thermal performance and design flexibility.

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Spray Polyurethane Foam (SPF)

SPF two-component low-pressure foams are designed to fill large voids and surfaces. They offer a high insulation value, are easy to install and stop air infiltration when installed properly.

Stopping unwanted air infiltration is one of the most important and cost-effective ways to reduce heating and cooling costs, improve indoor air quality, and provide a more durable, energy-efficient structure.

There are many considerations and options to create an ideal insulation solution for every building envelope. Contact your local White Cap location for more information.
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