Extruded Polystyrene Foam Insulation Association Backgrounder
WOODBRIDGE, VA – Residential and commercial builders are faced with many choices when it comes to selecting the most effective form of insulation for roofs, walls or foundations. Extruded polystyrene foam (XPS) maintains its excellent insulating power over time, resists moisture absorption and has compressive strength that, when compared to other insulation products, is second-to-none.
Many of the advantages of XPS foam are due to the extrusion manufacturing process employed.
XPS insulation boards begin as a solid granule. The granules are fed into an extruder where they are melted and critical additives are mixed with the viscous fluid that is formed. Then, a blowing agent is injected to make the mixture foamable. Under carefully controlled heat and pressure conditions, the foamable mixture is forced through a die, at which time forming and shaping occurs. The rigid foam is then trimmed to the final product dimensions.
This continuous extrusion process produces a consistent quality foam product with a closed-cell structure that looks like a mass of uniform bubbles with common walls between them. Close inspection reveals there are few, if any, voids between the cells and that a continuous smooth skin, top and bottom, has formed.
XPS insulating materials are available in either rigid boardstock or fanfold sheet versions and in a wide range of sizes, thickness and compressive strengths that are ideally suited to a variety of construction applications.
Following are some benefits and uses of XPS insulation:
Thermal Efficiency
The thermal efficiency of an insulating material is expressed as R-value. R-value is the material’s resistance to heat flow. The higher the R-value, the greater the insulating power. Other materials provide insulation, but none maintain R-value as well as XPS over time. R-value depends on trapped “air” within all types of insulation. If the trapped “air” is replaced with water or is squeezed out by crushing, the R-value is reduced. The high moisture resistance and high compressive strength of XPS help to maintain high R-value for many years in the harsh conditions of real-world applications. Why is R-value important? Incorporating high R-value insulation when building leads to less energy consumption by the building, creating lower operational costs. Put simply, insulation saves money. Surfaces in the living area are kept warmer when it is cold outside and cooler inside when it is hot, so, insulation makes buildings more comfortable. Proper type and placement of insulation outside reduces the potential for damage to the building due to cold, heat or moisture intrusion. Insulation can make buildings more durable. With these benefits, XPS will help you and your customers save energy and money, while improving the comfort of those inside and the durability of your structure.
Moisture Resistance
A critical factor affecting long-term energy performance is the ability of an insulating material to resist the intrusion of moisture. Moisture may come in contact with insulation not only during construction, but throughout the life of the structure. If absorbed, its effect is to drastically reduce the insulation’s R-value.
The closed-cell structure and lack of voids in XPS help it to resist moisture penetration better than all other types of insulating materials. The excellent moisture resistance of XPS foam insulation has been confirmed repeatedly and consistently in laboratory tests and under field-use conditions.
XPS foam does not corrode or rot. It is resistant to microorganisms found in soil and provides no nutrient value to vermin. These properties, coupled with its outstanding ability to resist water absorption, make it an outstanding insulating material for below-grade applications.
Compressive Strength
The closed-cell structure of XPS imparts excellent long-term strength and durability. Products are available in a range of compressive strengths to suit a variety of application requirements. Due to its inherent physical properties, this strength does not depend on the use of facers or laminates that are sometimes compromised during installation of the product.
Extruded Polystyrene Foam Insulation Uses
Exceptional moisture resistance, insulating efficiency and a variety of compressive strengths, combined with air infiltration reduction and labor savings make XPS insulation a suitable – even preferable – insulating material for use in commercial, industrial and residential structures, as well as for critical civil engineering uses.
All referenced XPS products comply with the International Residential Code (IRC), International Building Code (IBC), Uniform Building Code (ICBO), National Building Code (BOCA) and Standard Building Code (SBCCI) and are listed by UL (Underwriters Laboratories, Inc.) and other accredited third-party test laboratories.
Roofs
Light-weight high R-value, high compressive strength and moisture resistance make XPS foam an efficient, effective choice for residential or commercial roofing insulation – whether new or retrofit. Its weather resistance properties allow XPS to be installed under the membrane (the conventional system) or over the membrane to protect it from damage and weather.
Walls
Used with either wood or metal stud framing, XPS foam insulation provides a highly moisture-resistant thermal break to sheath and insulate all framing. XPS offers significant insulating performance while also reducing air infiltration. New or retrofit siding, brick and stucco finishes can then be applied.
Applied to masonry or concrete interior walls, XPS insulation can be used with furring systems or other attachment methods to provide energy efficiency. Because XPS is rigid and dimensionally stable, it does not “settle”.
Used in a “hard coat” cementitious, mechanically-attached exterior insulation system, XPS substantially reduces thermal bridging. The system provides a sturdy, thermally-efficient and attractive exterior.
Foundations
The long term R-value, high-compressive strength, exceptional moisture resistance and excellent resistance to chemicals typically found in soil make XPS ideal for use as foundation insulation. In fact, XPS is the only insulation allowed by building code in below-grade horizontal applications, such as frost protected shallow foundations.
Other XPS applications include: earth shelters; swimming pools; recreational vehicles; agricultural buildings; low-temperature space; ice rinks; pre-cast concrete systems; plaza decks; highway insulation; and airport runway insulation.
About Extruded Polystyrene Foam Association
The Extruded Polystyrene Foam Association (XPSA) is a trade association representing manufacturers of extruded polystyrene foam (XPS) insulation products and its raw material suppliers. XPSA members are The Dow Chemical Company, Owens Corning Inc., and Pactiv Corporation, who collectively manufacture more than 95 percent of all XPS foam products sold in the North American market. XPSA serves as the industry’s leader on product stewardship, conducting research to substantiate performance claims and promotes the benefits of XPS foam insulation applications. For more information, please look for XPSA’s website at www.xpsa.com, or call 800-978-9772.
For Editorial Information:
John R. Sternal
The Dutcher Group
866-593-2400
813-732-5984 (cell)
jsternal@dutchergroup.com
