Applying Siding over Rigid Foam Sheathing
F. APPLYING SIDING OVER RIGID FOAM SHEATHING: Rigid Form sheathing has an insulation value superior to that of traditional lumber and plywood sheathings. However, it has little or no nail holding power and using rigid foam sheathing as a nailing base for cedar siding is definitely not recommended. The nail must penetrate into a solid wood base ideally 1-1/2". For use over 1" foam sheathing the recommended nail is a 3-1/2". 16d splitters siding nail. In a all cases it is recommended that building paper or an equivalent building wrap be applied over the Foam Sheathing.
Download printable PDF version of the Application Instructions.
For further information, view the Western Red Cedar Lumber Association's installation information.