Insulation Materials
Insulation materials cover a broad spectrum, ranging from voluminous fiber materials like fiberglass, rock and slag wool, cellulose, and natural fibers to rigid foam boards and streamlined foils. Bulky materials excel in resisting conductive heat flow within building cavities, with some capacity to mitigate convective heat transfer. On the other hand, rigid foam boards utilize trapped air or another gas to impede heat flow effectively. Highly reflective foils, featured in radiant barriers and reflective insulation systems, redirect radiant heat away from living spaces, proving particularly advantageous in cooling climates. Additionally, less conventional options such as cementitious and phenolic foams, along with vermiculite and perlite, provide alternative solutions for specific insulation needs. This diverse array of materials allows for tailored insulation approaches, considering factors like thermal conductivity, environmental impact, and climate requirements.
Learn about the following insulation materials:
- Fiberglass
- Mineral wool
- Cellulose
- Natural fibers
- Polystyrene
- Polyisocyanurate
- Polyurethane
- Perlite
- Cementitious foam
- Phenolic foam
- Insulation facings
Fiberglass
Fiberglass stands as a pervasive insulation material, consisting of exceptionally fine glass fibers and finding versatile use in various insulation formats. Widely employed in blankets (batts and rolls), loose-fill, rigid boards, and duct insulation, it caters to diverse insulation needs.
Recent advancements have led to the production of medium- and high-density fiberglass batts with slightly elevated R-values compared to standard batts. These denser products are designed for insulating confined spaces, such as cathedral ceilings, offering improved thermal performance. For instance, high-density fiberglass batts for a 2 by 4-inch stud-framed wall boast an R-15 value, surpassing the R-11 of “low density” types. Similarly, a medium-density batt provides an R-13 for the same thickness. The R-values increase with thickness, with high-density batts for 2 by 6-inch frame walls offering R-21 and those for 8.5-inch spaces yielding about an R-30 value. Batts with R-38 for 12-inch spaces are also available.
Manufactured from molten glass spun or blown into fibers, fiberglass insulation incorporates 40% to 60% recycled glass content for sustainability. In loose-fill form, it requires an insulation-blowing machine for application in open-blow settings like attics or closed-cavity applications within existing walls or covered attic floors.
An innovative variation of fiberglass loose-fill insulation is the Blow-In-Blanket System® (BIBS), applied dry. BIBS stands out for its effective coverage, surpassing other fiberglass insulation forms like batts. Notably, the BIBS HP represents an economical hybrid system, combining BIBS with spray polyurethane foam for enhanced insulation performance. This progressive approach underscores the continuous evolution of fiberglass insulation technologies to meet evolving efficiency and sustainability standards.
Mineral Wool Insulation Materials
The term “mineral wool” encompasses two main types of insulation materials: rock wool and slag wool. Both of these are man-made materials designed for effective thermal insulation, each utilizing different raw materials in their production.
- Rock Wool:
- Rock wool is composed of natural minerals such as basalt or diabase. These minerals are melted at high temperatures and then spun into fibers to create the insulation material. The resulting product is resistant to fire and offers thermal insulation properties.
- Slag Wool:
- Slag wool is another type of mineral wool, manufactured from blast furnace slag. Blast furnace slag is the waste material that forms on the surface of molten metal during the extraction process. Similar to rock wool, slag wool is created by melting the slag and transforming it into fibers suitable for insulation.
Mineral wool insulation is notable for its environmentally friendly characteristics. It contains an average of 75% post-industrial recycled content, contributing to sustainability and resource conservation efforts. Importantly, mineral wool doesn’t require additional chemicals to make it fire-resistant, as its inherent properties provide natural fire resistance.
Mineral wool insulation is available in various forms, including blankets (batts and rolls) and loose-fill. This versatility makes it suitable for a range of applications, from residential and commercial construction to industrial settings. The fire resistance, thermal performance, and eco-friendly composition make mineral wool a popular choice in the insulation market.
Cellulose Insulation Material
Cellulose insulation, a sustainable and environmentally friendly choice, is crafted from recycled paper products, primarily newsprint, boasting an impressive recycled material content ranging from 82% to 85%. The manufacturing process involves reducing paper to small pieces and fiberizing it, resulting in a tightly packing product ideal for filling building cavities.
To enhance its properties, manufacturers introduce the mineral borate, often blended with ammonium sulfate, ensuring resistance to fire and insects. When installed at proper densities, cellulose insulation demonstrates the valuable characteristic of not settling in building cavities.
This insulation material finds application in both new and existing homes, serving as loose-fill in open attic installations or dense-packed in building cavities such as walls and cathedral ceilings. For existing structures, a specific installation process involves removing a strip of exterior siding, drilling three-inch holes into each stud bay, and using a filler tube to blow the insulation into the wall cavity, achieving a density typically ranging from 1.5 to 3.5 lb. per cubic foot. After installation, the holes are sealed, and the siding is restored to match the wall.
In new construction, cellulose insulation can be either damp-sprayed or installed dry behind netting. Damp-sprayed cellulose involves adding a small amount of moisture at the spray nozzle tip, activating natural starches in the product, which causes it to adhere inside the cavity. This type of cellulose is often ready for wall covering within 24 hours of installation. Alternatively, cellulose can be blown dry into netting stapled over building cavities, providing flexibility in installation methods for construction projects. The versatility, sustainability, and fire-resistant properties make cellulose insulation a favorable choice for a range of insulation needs.
Several natural fibers, including cotton, sheep’s wool, straw, and hemp, serve as insulation materials, providing sustainable alternatives to traditional options.
Cotton:
- Cotton insulation is composed of 85% recycled cotton and 15% plastic fibers treated with borate, offering flame retardancy and resistance to pests. Some products use recycled blue jean manufacturing trim waste, minimizing energy consumption during manufacturing. Cotton insulation is available in batts.
Sheep’s Wool:
- Sheep’s wool, treated with borate to resist pests, fire, and mold, serves as insulation material. Batts designed for 2 by 4-inch and 2 by 6-inch stud-framed walls provide R-13 and R-19 values, respectively.
Straw:
- Straw bale construction, which gained popularity on the Great Plains 150 years ago, has seen renewed interest. The process of fusing straw into boards without adhesives was developed in the 1930s. These panels, typically 2 to 4 inches thick, feature heavyweight kraft paper on each side. They also function as effective sound-absorbing panels for interior partitions. Some manufacturers have created structural insulated panels from compressed-straw panels.
Hemp:
- Hemp insulation, although less commonly used in the United States, offers a sustainable option. Its R-value is comparable to other fibrous insulation types.
These natural fiber insulation materials contribute to environmentally conscious construction practices. They often undergo treatments, such as borate application, to enhance resistance to pests, fire, and mold. As sustainability gains prominence in the construction industry, the use of these natural fibers is likely to see continued interest and adoption.
Polystyrene Insulation Materials
Polystyrene, a colorless and transparent thermoplastic, is widely utilized in various insulation applications. Commonly used forms include foam board or beadboard insulation, concrete block insulation, and a loose-fill insulation variant consisting of small polystyrene beads.
Molded Expanded Polystyrene (MEPS):
- MEPS is frequently employed for foam board insulation and is also available as small foam beads. These beads can serve as pouring insulation for concrete blocks or other hollow wall cavities. However, they are exceptionally lightweight, prone to static electric charge, and can be challenging to control.
Expanded Polystyrene (EPS) and Extruded Polystyrene (XPS):
- EPS and XPS, similar to MEPS, are other types of polystyrene insulation materials. EPS consists of fused-together small plastic beads, while XPS is formed by pressing molten material into sheets. XPS is commonly used as foam board insulation, while EPS is produced in blocks suitable for cutting into board insulation. Both EPS and XPS find applications in structural insulating panels (SIPs) and insulating concrete forms (ICFs). It’s worth noting that over time, the R-value of XPS insulation may decrease due to thermal drift or aging as some low-conductivity gas escapes and is replaced by air.
Thermal Resistance (R-value):
- The thermal resistance or R-value of polystyrene foam board is contingent on its density. Polystyrene loose-fill or bead insulation generally exhibits a lower R-value when compared to foam board insulation.
Polystyrene’s versatility makes it a popular choice in the construction industry for its insulation properties. However, considerations such as the specific application, desired R-value, and long-term performance should guide the choice between different forms of polystyrene insulation.
Polyisocyanurate Insulation Materials
Polyisocyanurate, often referred to as polyiso, is a thermosetting plastic with a closed-cell foam structure, containing a low-conductivity, hydrochlorofluorocarbon-free gas in its cells. This type of insulation is available in various forms, including liquid, sprayed foam, and rigid foam board. It can also be manufactured into laminated insulation panels with different facings.
Forms of Polyisocyanurate Insulation:
- Liquid and Sprayed Foam: These applications are adaptable and often more cost-effective than installing rigid foam boards. The liquid foam molds itself to all surfaces, providing effective insulation.
- Rigid Foam Board: Polyisocyanurate insulation in rigid foam board form is versatile and widely used. It is available with different facings for specific applications.
- Laminated Insulation Panels: These panels combine polyisocyanurate with various facings to enhance performance and application suitability.
Thermal Drift or Aging:
- Over time, the R-value of polyisocyanurate insulation can experience a decrease as the low-conductivity gas escapes, and air replaces it. This phenomenon is known as thermal drift or aging. Experimental data suggests that most thermal drift occurs within the first two years after manufacturing.
Facings and Radiant Barrier:
- Foil and plastic facings on rigid polyisocyanurate foam panels can help slow down the aging process. Reflective foil, when installed correctly and facing an open air space, can also act as a radiant barrier. Depending on the size and orientation of the air space, this can contribute an additional R-2 to the overall thermal resistance.
Use in Structural Insulated Panels (SIPs):
- Some manufacturers utilize polyisocyanurate as the insulating material in Structural Insulated Panels (SIPs). These panels, which can be 3.5 inches thick for wall panels and up to 7.5 inches thick for ceiling panels, offer advantages in fire resistance and water vapor-diffusion resistance compared to EPS (expanded polystyrene). They also provide better insulation efficiency for a given thickness.
Polyisocyanurate insulation, with its diverse applications and forms, is valued for its thermal performance, adaptability, and versatility in various construction scenarios. Considerations such as thermal drift, facing materials, and specific application requirements guide the selection and installation of polyisocyanurate insulation.
Polyurethane Insulation Materials
Polyurethane is a versatile thermoset foam insulation material known for its closed-cell and open-cell formulations, each offering specific characteristics.
Closed-Cell Polyurethane:
- In closed-cell polyurethane foam, high-density cells are closed and filled with a low-conductivity gas, allowing the foam to expand and fill spaces efficiently. The closed-cell structure provides a higher density and better insulation properties compared to open-cell foam. However, the R-value of closed-cell polyurethane insulation can experience thermal drift or aging over time as the low-conductivity gas escapes and is replaced by air. Foil and plastic facings on rigid polyurethane foam panels can help slow down this thermal drift.
Open-Cell Polyurethane:
- Open-cell polyurethane foam has less dense cells filled with air, giving it a spongy texture and a lower R-value. However, unlike closed-cell foam, the R-value of open-cell polyurethane foam does not change over time. Low-density, open-cell polyurethane foams can use air or carbon dioxide as the blowing agent.
Applications and Forms:
- Polyurethane insulation is available as liquid sprayed foam, rigid foam board, and laminated insulation panels with various facings. Sprayed or foamed-in-place applications of polyurethane insulation are often more cost-effective than installing foam boards. The liquid foam molds itself to all surfaces, providing effective insulation.
Structural Insulated Panels (SIPs):
- Some manufacturers use polyurethane as the insulating material in structural insulated panels (SIPs). Foam board or liquid foam can be injected between two wood skins under pressure, creating a strong bond between the foam and the skins. These panels, typically 3.5 inches thick for wall panels and up to 7.5 inches thick for ceiling panels, offer superior fire and water vapor-diffusion resistance compared to EPS (expanded polystyrene) and provide better insulation efficiency for a given thickness.
Soy-Based Polyurethane:
- Soy-based polyurethane liquid spray-foam products are available as environmentally friendly alternatives. These products can be applied with the same equipment used for petroleum-based polyurethane foam products.
Polyurethane insulation, with its varied formulations and applications, offers excellent thermal performance, adaptability, and versatility in construction. The choice between closed-cell and open-cell formulations depends on specific project requirements and considerations.
Perlite Insulation Materials
Perlite insulation materials, often found in homes built before 1950, are a form of loose-fill insulation commonly used in attics.
Composition and Manufacturing:
- Perlite is composed of very small, lightweight pellets. These pellets are created by heating rock pellets until they expand or “pop,” resulting in a lightweight and porous material. This expanded perlite is then used as insulation.
Application:
- Perlite insulation is typically used in loose-fill form. The lightweight pellets can be poured into place to fill cavities and spaces, providing thermal insulation. Additionally, perlite can be mixed with cement to create a lightweight and less heat-conductive concrete.
Benefits:
- Perlite insulation offers several advantages. Its lightweight nature makes it easy to handle and install. It provides thermal resistance, helping to control heat transfer. When used as loose-fill insulation, it can conform to irregular spaces, effectively filling gaps and voids.
Historical Usage:
- Perlite insulation was commonly used in homes constructed before 1950, particularly in attics. Over the years, other insulation materials with different properties and characteristics have become more prevalent in construction.
Applications Beyond Insulation:
- In addition to its use as insulation, perlite is a versatile material employed in various applications. Its lightweight and insulating properties make it suitable for uses in horticulture, construction, and industrial processes.
While perlite insulation has been widely used historically, advancements in insulation materials and building practices have introduced a range of alternatives with different characteristics and benefits. The choice of insulation material often depends on factors such as energy efficiency requirements, building codes, and specific project needs.
Cementitious Foam Insulation Material
Cementitious insulation material, specifically cement-based foam, is utilized as a sprayed-foam or foamed-in-place insulation. One notable type of cementitious spray foam insulation is known as Airkrete®.
Key Features of Cementitious Foam:
- Composition: Cementitious foam is cement-based and often contains minerals such as magnesium silicate. Airkrete®, for example, has an initial consistency similar to shaving cream.
- Application: This type of insulation is typically sprayed or foamed in place. The foam is pumped into closed cavities, filling and adhering to the surfaces to provide insulation.
- Cost: Cementitious foam costs approximately as much as polyurethane foam, a commonly used insulation material.
- Properties: It is known for being non-toxic and nonflammable, making it a safer option for certain applications.
- Source: The material is made from minerals, such as magnesium oxide, which are extracted from seawater. This can contribute to its environmental sustainability.
Airkrete®:
- Airkrete® is a specific brand of cementitious spray foam insulation. It is notable for its composition and application process, providing effective insulation in closed cavities.
Benefits:
- Nontoxic: Cementitious foam is considered nontoxic, making it a safer option for use in various settings, including residential and commercial construction.
- Nonflammable: The nonflammable nature of this insulation material adds an extra layer of safety to its application.
- Mineral-Based: Being made from minerals extracted from seawater contributes to the material’s environmental sustainability and reduces its environmental impact.
Cementitious foam insulation represents a viable alternative to traditional insulation materials, offering specific advantages such as non-toxicity, nonflammability, and a source of minerals derived from seawater. As with any insulation material, its selection depends on factors such as the specific application, building requirements, and environmental considerations.
Phenolic Foam Insulation Material
Phenolic foam, also known as phenol-formaldehyde foam, was once popular as rigid foam board insulation, but its availability has become limited in recent years. It is currently used as both board insulation and foamed-in-place insulation.
Characteristics of Phenolic Foam:
- Composition: Phenolic foam is made from phenol-formaldehyde resin. It typically includes a foaming agent to generate the foam structure.
- Rigid Foam Board Insulation: Phenolic foam was historically used as rigid foam board insulation. However, its popularity has waned over time.
- Foamed-in-Place Insulation: Phenolic foam is also available as foamed-in-place insulation. In this application, air is commonly used as the foaming agent.
Major Disadvantage: One significant drawback of phenolic foam is its potential to shrink up to 2% after curing. This shrinkage has contributed to its reduced popularity in modern construction compared to other insulation materials.
Limited Availability: While phenolic foam remains available for certain applications, its overall use has diminished, and it is not as widely used as other insulation options in the current market.
Insulation Facings
Phenolic foam, made from phenol-formaldehyde resin and often including a foaming agent, was once popular as rigid foam board insulation. However, its use has declined over time due to certain drawbacks.
Key Points:
- Composition: Phenolic foam is composed of phenol-formaldehyde resin, and a foaming agent is typically added to create the foam structure.
- Historical Use: It was historically employed as rigid foam board insulation, but its popularity has diminished.
- Foamed-in-Place Insulation: Phenolic foam is still utilized as foamed-in-place insulation, with air commonly serving as the foaming agent.
- Major Disadvantage – Shrinkage: One significant drawback is the potential for phenolic foam to shrink up to 2% after curing. This characteristic has contributed to its reduced popularity in modern construction.
- Limited Availability: While still available for specific applications, the overall use of phenolic foam has declined, and it is not as widely used as other insulation options in the current market.
When selecting insulation materials, builders and contractors often consider factors such as thermal performance, cost-effectiveness, ease of installation, and long-term stability. The shrinkage issue with phenolic foam has led to its limited application, with alternative materials gaining more prominence in contemporary construction projects.
