DuPont™ Styrofoam™ Brand Tongue and Groove Extruded Polystyrene Foam Insulation

Commercial | Residential | Multifamily | Wall

Locking design means more coverage per board

Designed with grooves to lock into the next sheet, Styrofoam™ Brand Tongue and Groove Foam Insulation is easy to install and lightweight while providing moisture resistance and thermal efficiency.


DuPont™ Styrofoam™ Brand SM Extruded Polystyrene Foam Insulation

Styrofoam™ Brand Tongue and Groove Extruded Polystyrene Foam Insulation (XPS)* features tongue and groove edges on all four sides of 2’ x 8’ boards 1” thick or less and on the long edges of all other boards. The lightweight, moisture-resistant and thermally efficient Type IV extruded polystyrene foam insulation is suited for a wide range of residential and commercial construction applications.

* Styrofoam™ Brand Tongue and Groove Insulation is a former product of The Dow Chemical Company


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 Resistance1 per inch @ 75°F mean temp. @ 40°F mean temp. @ 25°F mean temp.1 ASTM C518 ft2 •h•°F/Btu, R-value, min. 5.0
    - - 5.4
    - - 5.6
    Compressive Strength2 ASTM D1621 psi, min. 25
    Water Absorption ASTM C272 % by volume, max. 0.3
    Water Vapor Permeance3 ASTM E96 perm, max 1.5
    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

    1 R means resistance to heat flow. The higher the R-value, the greater the insulating power.

    2 Vertical compressive strength is measured at 10 percent deformation or at yield, whichever occurs first. Since Styrofoam™ Extruded Polystyrene Foam Insulations are visco-elastic materials, adequate design safety factors should be used to prevent long-term creep and fatigue deformation.

    3 Based on 1” thickness.  


    Available sizes


    Thickness1 (in.) Board Size (ft.)
    0.75 2 x 8, 4 x 8
    1 2 x 8, 4 x 8
    1.5 2 x 8, 4 x 8
    2 2 x 8, 4 x 8

    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.