2X6″ 24 ” oc framing and siding question
Hello building world,
Long time leacher of information from here, enough to make my head explode. First thanks for the entire community has offered so far.
My wife and I are building our forever home in Northern California, climate zone 3B. Seismic category D1. Wind category 95mph. Windland urban interface area (meaning high fire area, the lot was actually a fire burn lot).
Now that the technical data is out of the way, we have gone with modified advanced framing for our wall assembly. Our builder agreed with 2×6″ with 24″ oc but still wanted to do double top plates and other framing techniques. We are about done with rough framing and roof decking applied. Zip is going to be taped next. We are also going to have 1″ continuous insulation over the sheathing. EPS foam.
My question/ concern is about siding. We are doing a modern build with stucco/ board and batten and accent of wood look siding. I have found several aluminum or wood look fiber cement lap siding that I would love to use. However going through the technical data, most only allow for 16″ oc max. Clearly many other builders have gone to 24″ oc framing, yet most siding does not seem compatible with this?
What are people doing to remedy this? Would putting up furring strips with intermediate furring strips (attached to top and sill plate and sheathing) be a possibly solution. This would effectively make it 12″oc but not sure how much weight the intermediate furring strips would support.
I have emailed a few companies asking what they think about methods to get onto 24″ oc framing, but also wanted to pick you problem solver brains.
Disclaimer: I am not an expert in building and have only been researching for the past year as we have been planning and building. So please excuse my inexperience and if I am blatantly overlooking something, please let me know.
GBA Detail Library
A collection of one thousand construction details organized by climate and house part
Replies
You may have just not come across the information you need, yet. Here's an ICC-ES Evaluation Report for James Hardie showing the design wind speeds for various wall assemblies and their rated wind speeds. It has other good data like fastening schedules and all that.
The data you need is likely on page 19 of this pdf: https://www.jameshardie.com/JamesHardieMainSite/media/Site-Documents/TechnicalDocuments/Reports/esr-2290.pdf.
An image of the row is extracted here for demonstration:
It looks like with 2" siding nails, without insulation, attached to the studs, you're looking at 100-120 mph wind design speeds, which exceed your 94 mph criteria. Note that this is without the 1" of EPS attached, but I would feel pretty confident that it would be fine if I used a 3" ring shank nail to attach through to the studs.
It shows 2x4 wood studs, but the distinction between x4 and x6 doesn't matter here.
According to their docs, you don't really need furring strips, just a high drainage efficiency house wrap. It's not a bad idea, as that gives you a chance to use 'better fasteners' for the task, but at the end of the day I'm not sure you'd notice a difference in performance.