Molded Polystyrene vs Extruded Polystyrene (XPS)

 

Image is nice but performance is what really matters. Understanding the differences between the types of rigid foam insulation can save you up-front material cost and improve energy performance for the life of the building. An evaluation of Foam-Control® Plus+® molded polystyrene insulation and extruded polystyrene (XPS) will help you choose the right rigid foam insulation for your project.

 

Foam-Control® Plus+® is an industry leading architectural grade  insulation with a high compressive strength and high R-Value. It’s designed to give architects, designers, and contractors all of the benefits of a high quality insulation: strength + energy efficiency + moisture resistance, bundled together to equal a budget friendly product that will help keep project costs on track.

 

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Molded Polystyrene	Extruded Polystyrene (XPS)
Raw Material
Polystyrene resin	Polystyrene resin
Manufacturing Process
Plastic resin is expanded, then molded together to form a closed-cell material that uses trapped air as its insulating medium.	Plastic resin is liquefied, then extruded through a die and expanded to form a closed-cell material that uses trapped air as its insulating medium.
Compressive Strengths
15, 25, 40, 60 psi	15, 25, 40, 60, 100 psi
R-Value & Energy Efficiency
Foam-Control® Plus+® 250 is R-4.8 per inch at 40°F and R-4.4 per inch at 75°F.	XPS is R-5.4 per inch at 40°F and R-5.0 per inch at 75°F.
R-Value Warranty
50-Year R-Value Warranty.	50-Year R-Value Warranty.
Moisture Performance in 15-Year Real World Test (Molded Polystyrene & XPS side-by-side on the same building)
Excavated after 15-years as a below-grade foundation insulation, the molded polystyrene had retained 94% of its published R-value and contained only 4.8% moisture content. The R-value at the time of excavation showed that molded polystyrene is less affected bymoisture content than XPS.	Excavated after 15-years is a below-grade foundation insulation, XPS only retained 52% of its published R-value and contained higher moisture content of 18.9%. The R-value at the time of excavation reflected that XPS is greatlyaffected by exposure to moisture.
Permeability
Higher rate of permeability allows Foam-Control® Plus+® to expel moisture faster and maintain R-value.	Lower rate of permeability delays the drying process and results in greater time to recover lost R-value when exposed to moisture.
Recycled Content
Contains up to 15% recycled content. ACH Foam Technologies recycled 5.4 million pounds of molded polystyrene in 2013.	Has limited amounts of recycled content. Not offered in all products.
Environment & Sustainability
molded polystyrene has never contained HFCs, CFCs, HCFCs, formaldehyde, or color dies. The natural color of polystyrene rigid foam is white.	In 2010, XPS finally discontinued the use of HCFCs. XPS contains color dies, such as pink, blue or green to brand & market their product.
Constructability
Widths: 8”, 12” 16”, 24”, 36”, or 48” Lengths: 2’, 4’, 8’, 9’, 10’ or 16’ Thicknesses: ½” up to 36” in any variation. Variety of R-Values in single sheet thicknesses.	Widths: 16”, 24” or 48” Lengths: 8’ Thicknesses: ¾”, 1”, 1-½”, 2”, or 3” Limited sheet thicknesses for R-Values.
Testing, Codification, Certification
ASTM C578, “Standard specification for Rigid Cellular Polystyrene Thermal Insulation.”  Is monitored for quality control by UL and is code approved by the International Code Council Evaluation Service and UL ER 11812-01.	ASTM C578, “Standard Specification for Rigid Cellular Polystyrene Thermal Insulation.”  Is monitored for quality control and is code approved by the International Code Council Evaluation Service.
Cost
At equal R-values Foam-Control Plus+, costs 10-30% less.	At equal R-Values, costs 10-30% more.
Which rigid foam insulation would you choose?