Fastening Siding to Furring Strips
I am building an addition in Ottawa, Canada and plan to have 3” of exterior mineral wool insulation on my walls with 3/4” strapping at 16”, aligned with the studs behind. With thanks to previous Q&A’s, I think I have that part figured out…
However, I am realizing that the installation instructions for all siding manufacturers I have found, other than some vinyl siding, require 1” to 1.5” of embedment of the fastening nails into the supporting structure but I have 3/4” max unless I fasten right through the insulation to the studs.
Rain screens with 3/4” furring strips seems very common (and generally recommended) on GBA, so I am wondering how others have addressed this? Ring shank nails? Long fasteners back to the studs? Regular siding nails/what embedment requirement?
We are far from any coast and have much lower design wind speeds than many coastal applications that are presumably covered by the catch-all installation instructions.
Thanks in advance!
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Below is a link that should help you.
"According to building scientist Joseph Lstiburek, if you have any doubts arising from the fact that your siding nails penetrate into only ¾ in. of wood, just switch from smooth-shank nails to ring-shank nails. Unless you’re building near the coast in south Florida, ring-shank nails will be more than adequate, even when penetration into wood is only ¾ in."
https://www.greenbuildingadvisor.com/article/fastening-furring-strips-to-a-foam-sheathed-wall
The above quote is good. I'll add that some manufacturers specify 2 nails per furring strip in some circumstances, to make up for the half depth embedment in the furring strips.
If you care about your future self, or future installers, realize that they'll have to rip those ring shanks out, and while they've got tremendous holding power, they've quite difficult to remove. Especially since it's probably hot, cold, frustrating, etc.. If you don't need the ring shank nails for the wind load, I'd consider two smooth shank galvanized in place of one ring shank.