This Customer Bulletin is another in a series of white papers aimed at providing our clients, engineers, contractors, fabricators, and friends with objective information on competitive products. Marketing literature on the internet and in printed media address the physical and performance characteristics of polyisocyanurate rigid foam (ISO) and extruded polystyrene insulation (XPS). As is often the case, some literature can be misleading and/or in some cases there may not be sufficient information to credibly compare products. This Customer Bulletin provides factual, clarifying information which should allow for an objective comparison of Dyplast’s ISO-C1® with the competing XPS Billet product.

1. CUSTOMER BULLETIN 0310
A Comparison of ISO-C1 Polyisocyanurate Insulation
to Extruded Polystyrene (XPS)
PURPOSE
This Customer Bulletin is another in a series of white papers aimed at providing our clients,
engineers, contractors, fabricators, and friends with objective information on competitive
products. Marketing literature on the internet and in printed media address the physical and
performance characteristics of polyisocyanurate rigid foam (ISO) and extruded polystyrene
insulation (XPS). As is often the case, some literature can be misleading and/or in some cases
there may not be sufficient information to credibly compare products. This Customer Bulletin
provides factual, clarifying information which should allow for an objective comparison of
Dyplast’s ISO-C1® with the competing XPS Billet product.
SUMMARY OF RESULTS
When it comes to selecting the best overall insulation product for pipe insulation for low
temperature systems, polyiso is the product of choice over extruded polystyrene (XPS). In fact,
no other foam insulation has the combination of features so important for long term performance.
For example, polyiso insulation:
 Delivers the highest R-value per inch of thickness
o Aged R-value of ISO-C1 is 5.7 versus 3.861 for XPS
 Is moisture resistant, water repellent, and will not wick moisture
o ISO-C1 has water vapor permeance of 1.65 perm-inch per ASTM E96, and when
properly installed with zero-perm vapor barrier the insulation system has superior
properties
 Possesses excellent dimensional stability, particularly at lower temperatures
o ISO-C1 has <0.1% change in volume or length at -40F
 Demonstrate excellent performance in fire tests
o ISO-C1 ASTM E-84 tests demonstrate 25 flame spread and 130 smoke
developed2 up to 4 inches in thickness
 Has low Global Warming Potential
1
ITW Insulation System’s Product Information sheet on XPS pipe insulation billets (XPS TDS, Form No. 10010-
0709)
2
Per Factory Mutual ASTM E-84 tunnel tests
Customer Bulletin 03-10 March 2010

2. o ISO-C1 utilizes hydrocarbon blowing agents with GWP ratings of approximately
10; XPS pipe insulation billets still continue to be sold with HCFCs3 which can
have GWP ratings of over 2000.
THIRD PARTY INDEPENDENT TESTING
Dyplast Products utilizes independent testing facilities to evaluate the physical properties of its
polyisocyanurate products. When comparing competitive foam insulations, buyers and specifiers
should request third party verification information in order to ensure their comparisons are
credible.
THERMAL PERFORMANCE
Polyiso insulation delivers more R-value per inch of thickness than extruded polystyrene
products. For example, ISO-C1’s aged R-value of 5.7 provides a benefit of 45% over extruded
polystyrene with an R of 3.86. This benefit produces considerable savings in energy
consumption as well as process efficiencies.
FIRE TEST PERFORMANCE
Not all foam plastic insulations perform equally in fire tests, including the ASTM E-84 “tunnel
test”. Polystyrene insulations are thermoplastic materials, which soften at 165°F and melt
between 200°F to 210°F. Because of the high temperatures reached in the E-84 test, polystyrene
melts and drips to the bottom of the tunnel as it burns and smokes.
Although many polystyrene insulations claim a Flame Spread of 5, PIMA4 notes that “ignition of
molten residue on the furnace floor results in flame travel equivalent to calculated flame spread
classification of 45 and smoke developed classification of 350 for 1 inch thickness - - -, and
90/500 for 4 inches”. On the other hand ISO-C1, a thermoset material, stays intact during the fire
exposure and successfully performs by forming a protective char layer and remaining in place
during the tunnel test. Factory Mutual (FM) has certified ISO-C1 to have a 25/130 rating, and
Underwriters Laboratory (UL) rates ISO-C1 as 25/195 for up to 4 inches in thickness.
3
ITW Insulation System’s Product Information sheet on XPS pipe insulation billets (XPS TDS,
Form No. 10010-0709) notes billets with HCFC’s continue to be marketed.
4
Polyisocyanurate Insulation Manufacturer’s Association
Customer Bulletin 03-10 March 2010

3. BILLET/BUN SIZE
ISO-C1 is produced as continuous bunstock that can be produced in variable sizes; for instance 2
lb/ft3 foam can have widths up to 4 feet and lengths up to 24 feet. Variable bunstock sizing and
subsequent cutting into precisely sized “chunks” can lead to efficiencies in shipping
(optimization of truck volumes) and during fabrication into pipe shapes (less waste). ISO-C1 can
also be produced in multiple densities, including 2.5, 4, 6, and 10 lb/ft3; higher densities provide
significant flexibility for various applications, including pipe hangars. XPS is commonly
produced only in 1.8 lb/ft3 billets, with limited size alternatives, the largest of which is typically
10” x 20” x 9’.
GLOBAL WARMING POTENTIAL (GWP)
Polyisocyanurate insulation manufacturers have been required to discontinue use of CFCs and
HCFCs, and thus now utilize hydrocarbon blowing agents such as pentane which has a GWP of
approximately 10. XPS pipe insulation billets still continue to be sold with HCFCs which can
have GWP ratings of over 2000.
RESISTANCE TO CONSTRUCTION MATERIALS
Extruded polystyrene can be attacked by many petroleum based solvents in adhesives, paints,
stains, water repellent and preservative coatings, and in bituminous waterproofing. As many
contractors have discovered, the application of these common construction materials causes the
extruded polystyrene to dissolve. This problem is solved by using ISO-C1 polyiso insulation,
which is not affected by these materials.
Customer Bulletin 03-10 March 2010