Installing Fiber Cement Siding over Rigid Foam
Does anyone have a best practice recommendation for installing fiber cement siding over rigid foam?
I know that the typical recommendation when installing exterior foam (1″ or more) is to place 1×3 furring strips on top of the rigid foam and then attach the siding to the furring strips. However, James Hardie and Certainteed both seem to recommend at least 1 1/2″ of nail penetration when attaching their fiber cement siding (I believe the warranty is voided if you do not follow this spec). If installing their fiber cement siding directly over rigid foam they do not recommend any more than 1″ of rigid foam and they seem to prefer no more than 1/2″ of rigid foam (the main concern being that the nails will sag if driven through anything thicker than 1″ of rigid foam).
Also, will fiber cement siding have any waviness when installed over furring strips (it seems very thin and flexible)?
Any thoughts or comments would be appreciated. Thanks.
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Replies
Follow the manufacturer's installation specifications or use a different siding.
James Hardie has a letter on their website that approves the use of their siding product over 1x furring strips with a required nail/screw length. Certainteed has not approved this means of construction yet. I would think they would want to test their product on these meanse to stay ahead of the game. Rainscreens are the wave of the future.
Rainscreens are the rave of the present, along with Ice and Water Shield on every conceivable building surface or opening.
They are both overused and poorly understood, and can create as many problems as they are intended to solve.
I tend to avoid them both, and have been building durable homes for more than 30 years with time-proven methods and materials.