horizontal strapping for reverse board and batten
Hello,
I am considering the details for horizontal rainscreen strapping for 7/8 thick spruce for either board on board or reverse board and batten. I understand that some folks are just installing it horizontally, while others are shimming the 3/4″ strapping out with 1/2 inch plywood spacers at the studs to promote better veritical airflow. I would be interested in a link to this discussion if it has happened on GBA before, or opinions on horizontal strapping in this case.
Also, I am concerned about nail length with the spacer approach. I plan on shooting it with stainless coil ringshanks. With reverse b and b, the nail should pass through the strapping but not into the sheathing, right? If it did, it would bend the strapping back to the sheathing and be uneven. If this is right, then I would need 1 3/4″ nails for the battens and 2 3/4″ nails for the boards so as to penetrate the strapping but not the sheathing. This would give me 3/4″ purchase into the strapping. Sound right?
Stephen
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Replies
Reverse B&B doesn't need any strapping as it is self venting, you can nail it all up to the sheathing.
If you want to install horizontal strapping anyways (I guess it helps as it keeps the battens off the sheating), there is no need to gapping as you get plenty of airflow where the boards are installed.
The only downside to running reverse B+B vertically is that the battens are typically sitting tight to the WRB and can take a while to dry out, potentially leading to rot. I use strips of Obdyke Hydrogap, or a spun-bonded matrix such as Slicker Classic, to keep the battens off the WRB.
Stephen,
Check your code. Our precludes horizontal strapping against the WRB, even if there is a drainage path outside that.
Thanks for the replies. I am in Maine. Michael, would you know the answer to Malcolm's question? Can I horizontally strap directly to zip sheathing?
My siding is pretty beefy: 1x8 and its nearly an inch thick, so I would like to fasten it securely. I would much, much rather strap than block at this point. I will have my pump jack scaffolding in place to work each side. UNless I am missing something, with 16 o.c framing, I would need to block if I ran battens directly to the WRB without strapping. Screwing into 7/16 sheathing and hitting the occasional stud wouldn't work, right?
Stephen, you can strap horizontally here. I don't recommend doing so without allowing a path for drainage, though. A client and I came up with a solution of ripping strips of Obdyke Slicker Classic and stapling them to the back of 1x3 battens installed horizontally. They don't allow much airflow but do provide a drainage path, and cost less than the many commercially available options out there. I have also used diagonal furring but it always results in areas that are awkward to deal with.
You can eliminate the horizontal furring and fasten directly to the sheathing, it's just riskier. It depends to some degree on the material. I have done that with KD white pine 1x8s and it has been fine for a few years now, though not the most robust system. I've also done it with 1x6 cedar which has been fine for longer than that, and less risky. If you're installing green 5/4 hemlock, it is likely that the boards will cup enough over time that they would pull fasteners through the sheathing.