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Styrofoam SIS
The innovative Styrofoam SIS brand structured insulated sheathing from Dow

Styrofoam Sheathing

The Styrofoam SIS brand structural insulated sheathing from The Dow Chemical Company has been proven to save money for both builders and homeowners alike. 

The product was designed to provide for structural lateral bracing and transverse loads, energy performance, and weatherization all in one.  This is because the sheathing is composed of three layers.  The first barrier is a structural layer, the second a moisture barrier, while the third is the foam insulation.  When used, it eliminates the need for wood structural panels and housewrap, wood let-in bracing, or metal T-bracing.

The sheathing weighs approximately 16 lbs. per 4’ by 8’ (0.5’ thick) board.  OSB of comparable size will typically weigh about 45 lbs.  This allows installation to be quick and easy.

The Styrofoam SIS structural insulated sheathing will provide an R-value of 3 at ½ inch or 5.5 at 1 inch.  The foam insulation is made out of a closed-cell, moisture resistant polyisocyanurate foam core.  This provides for its compressive strength and R-value.  It is worth noting that the Styrofoam SIS brand insulated sheathing is the first structural insulated sheathing to achieve significant R-values while meeting the criteria for shear evaluation as defined by ICC-ES AC269. 

Dow claims that the use of the product can save a homeowner between $200 to $500 per year on their energy bill.  The sheathing product can save the builder money as well.  This is because it allows the builder to install structural support, insulation, and a water resistant barrier with one product.  This, in turn, reduces the cost of labor. 

The Styrofoam SIS structural insulated sheathing contains up to 80% post consumer recycled content.  This helps builders qualify homes for certain Leadership in Environmental Design (LEED) credits.


The Dow Chemical Company
Phone: (866) 583-2583






  Energy Efficiency
  Renewable Energy


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