What is the appropriate fastener length to use for installing cedar shingle siding over insulation?
Assuming local Building Official approval for this type of installation is obtained, you should use the length of nail recommended for that specific material. Add the thickness of the existing insulation and this gives you the nail length required for the fastener to penetrate ¾” or more into the sheathing. Refer to the CSSB’s Exterior and Interior Wall Manual.
