Installing Wood Siding Over Rigid Insulation

Exterior rigid insulation 1x3 wood furring strips masonry structure 2x4 framing attached to surface of masonry.

Installing wood siding over rigid insulation.

Wood siding including cedar siding should be installed over an air space regardless of the type of sheathing used. With foam sheathing an air space is essential both to reduce the siding s water uptake and to provide a. Wood siding applied directly to foam has a history of failures. Installing house wrap with rigid foam insulation.

Cover the house walls with 4 by 8 foot sheets of rigid foam insulation typically 1 2 to 1 inch thick nailed to wood sheathing with 1 1 2 inch broad headed galvanized nails every 16 to 18 inches. The illustration below comes from the vinyl siding institute. Gypsum sheathing with combined thickness of 1 inch or less method 2 james hardie siding installed to furring strips that are attached through the c i. When installing wood siding over rigid foam sheathing you must protect the siding from moisture and heat buildup and use proper nailing.

Nailing wood siding directly to foam doesn t work because nails have to be extra long to reach through the siding and foam to a solid nail base. And other non nailable substrates e g. Plus rigid foam insulation applied over the outside walls. Moisture protection and heat buildup.

The answer happily is yes. Installation details are key. Julie the installation instructions of the vinyl siding institute and most if not all vinyl siding manufacturers allow vinyl siding to be installed over rigid foam sheathing. Cladding attachment over thick exterior rigid insulation peter baker p eng.

Since foil faced foam is a moisture barrier it should be used with a continuous film vapor retarder on the inside wall. I don t think builders should install wood siding directly over plastic foam insulation. What are the risks of installing cedar siding directly over foil faced rigid foam insulation should tar paper or housewrap be used as well. The vsi installation manual notes when the fastener must penetrate through a non nailable material such as foam sheathing the thickness of that material.

A vented drainable air space keeps wood siding dry and stable. It adds up to a robust system. In fact the two products combined make your home super insulated from outside wind and weather. To siding 1 embedment 3 5 0 5 1 5 1 5.

A homeowner in southwest virginia wants to install engineered wood siding over exterior foam insulation but finds that the manufacturer s installation instructions raises concerns he hadn t thought of.