DuPont™ Styrofoam™ Brand Ultra SL Extruded Polystyrene Foam Insulation

Commercial | Residential | Multifamily | Wall

Thermal performance for lasting efficiency

Durable and moisture resistant, Styrofoam™ Brand Ultra SL Extruded Polystyrene Foam Insulation provides continuous insulation as part of a complete 4-in-1 wall system.


DuPont™ Styrofoam™ Brand Ultra SL Extruded Polystyrene Foam Insulation

Styrofoam™ Brand Ultra SL Extruded Polystyrene Foam Insulation* is a moisture-resistant, durable and lightweight extruded polystyrene foam board with shiplap edges designed specifically to be used as a continuous insulation (ci) and installed over block, concrete or metal stud backup behind masonry or stone veneers. Manufactured with a patented carbon-black technology, Styrofoam™ Brand Ultra SL Insulation features an R-value of 5.6 per inch (RSI of 0.97 per 25 mm)**, the highest of all extruded polystyrene foam insulation products. With its closed-cell structure offering advanced long-term thermal performance and moisture control, Styrofoam™ Brand Ultra SL Insulation with shiplap edges maximizes the performance of the entire wall assembly.



Features & benefits

Feature Benefit
Lockable edges speed installation
  • Easy to use
  • Moisture Resistant
  • Resistant to moisture infiltration, condensation, and freeze-thaw cycles

    Physical properties

    Method Unit Value
    Thermal Resistance per inch @ 75°F mean temp. 1.75” 2.125” 2.5” 3.0” ASTM C518 ft2 •h•°F/Btu, R-value, min. 10.0
    - - 12.0
    - - 14.0
    - - 16.8
    Compressive Strength ASTM D1621 psi, min. 25
    Water Absorption ASTM C272 % by volume, max. 0.3
    Water Vapor Permeance 1.75” 2.125” 2.5” 3.0” ASTM E96 perm, max 1.1
    - - 0.8
    - - 0.65
    - - 0.50
    Maximum Use Temperature - °F 165
    Coefficient of Linear Thermal Expansion ASTM D696 in/in•°F 3.5 x 10-5
    Flexural Strength ASTM C203 psi, min. 50
    Flame Spread ASTM E84 - 50
    Smoke Developed ASTM E843 - 155

    1 Values are consistent with the criteria of ASTM C578 and the FTC R-value rule (16 CFR Part 460).

    2 Vertical compressive strength is measured at 10 percent deformation or yield, whichever occurs first. Since Styrofoam™ Brand Extruded Polystyrene Foam Insulations are visco-elastic materials, adequate design safety factors should be used to prevent long-term creep and fatigue deformation. For static loads, 3:1 is suggested. For dynamic loads, 5:1 is suggested. Contact DuPont for design recommendations.

    3 These numerical flame-spread and smoke-developed ratings are not intended to reflect hazards presented by this or any other material under actual fire conditions.


    Available sizes



    1Not all product sizes are available in all regions. Additional product sizes are available by custom order. Consult your DuPont sales representative about other sizes and lead-time requirements.

    2R means resistance to heat flow. The higher the R-value, the greater the insulating power. R-values are expressed in ft2 x h x°F/Btu. R-value determined by ASTM C518.

    34’ x 10’, 4’ x 12’ lengths available through special order.