Nails for siding?

[MushCreek]

This should be easy to find out, but I'm not having any luck. I'm going to use Nichiha fiber cement siding on out house, and plan to use 1X3 or 1X4 furring strips over foam board to create a (recommended) drainage plane. The question is- how long should the nails be? I've been to the Nichiha and Hardi sites, and they don't address using furring strips. Since the strips will be 3/4" thick, and the siding is 5/16", I'm assuming 1-1/4 or 1-1/2 nails will work, since they'll be long enough to go through the furring. At $150/box of stainless steel nails, I don't want to order wrong! Any ideas?

[Don_P]

1-3/4" is usually suggested, I'm using certainteed right now and just checked their lit. Nothing on furring strips. They want 1-1/4" penetration into the framing. (They also have a nail schedule for SIPS with no framing)

Edit;
I realize its a different vendor but there is some rainscreen info here;
http://www.certainteed.com/Pros/Technical-Information

[Danfish]

Do an on-line search for stainless nails...puchased 2 inch ring shank from Amazon last year for $60 per box (1000 colated nails)...same exact nails from local supplier were $100 + per box.

[MushCreek]

It's a little frustrating that the general consensus is that it's best to attach the siding over a drainage plane, but then none of the manufacturers seem to address this technique. Some say you need 1" of nail into the wood, some say 1-1/4, but in this case, the wood is only 3/4" thick.

I would guess that any nail long enough to fully punch through the furring strips should be sufficient; any additional length seems superfluous. Or should I use 2X's for a drainage plane? That would make the walls excessively thick, what with 2X6 framing, plus foam, plus furring. Right now, I'm thinking 1-1/2", which would theoretically go 7/16" through the furring into the foam. I'd just hate to spend all that money on nails, only to have the inspector flunk me.

[firefox]

Why not ask the inspector?
Bruce

[MushCreek]

I guess I could try to reach the inspector by phone- he's 600 miles away, and rarely available. I'm trying to order all of my nails before I get back to work on the house, since I don't have Internet there.

I've looked all over, and found numerous examples of using 1X for furring, yet NONE of them talk about fastenings! They do talk about fastening the furring strips through the foam to the studs, but it stops there. Even my book from JLC on energy efficiency talks about the technique, but makes no mention of appropriate fastenings.

All of the manufacturers call for 1-1/4" penetration into wood, so that leaves me with 2X furring. I guess all of the references I see for 1X furring are getting away with it- for now. As a matter of fact, I haven't seen reference to anything BUT 1X furring, except for metal, or expensive rain screen 'systems'. The technology is too new to predict what will happen 20 years down the road.

[Don_P]

My concern with rainscreen and thin siding is whether it will stay flat over time and then impact. I remember discussion on an inspectors' forum and don't remember concensus. SIP nailing is to a thinner substrate.
The ICC-ES report is here, I haven't read it thoroughly, check out the attachment tables at the end, first thing I notice is that face nailing is about 4 times stronger.
http://www.icc-es.org/reports/pdf_files/ICC-ES/ESR-2894.pdf
If he has been allowing blind nailing and you face nail to just about anything, it will hold the siding on better than the blind nail.

[Alan Gage]

I went the other direction with my rain screen - thinner. When I started out I planned using 3/4" furring strips but instead used 4mm coroplast (the stuff they use for political yard signs). Mine is 1/2" cedar siding over plywood sheathing. I think I went with 2 1/2" in ring shanks and nailed directly into the studs. Of course I didn't have foam outside my walls so depending on how thick yours is that might not work for you.

Building science recommends 3/8" for a drainage plain but if you read a little deeper in some of the articles you'll find they say the recommendation for 3/8" is because that should work for pretty much any house anywhere. That significantly smaller gaps will be fine for most houses. Considering mine was is a single story with 3' overhangs in a relatively dry climate I'm quite comfortable with my gap. The stuff was really easy to work with and install too.

Have you searched at green building adviser? Exterior foam and rain screens are all the rage there. I know I've read conversations on this very topic there but don't remember the specific answers.

Some pictures of my rainscreen are on this build page (and the next one too)

http://countryplans.com/smf/index.php?topic=10497.25

Building science article on rainscreens: (more specifics on gap size are in the footnotes at the bottom)

http://www.buildingscience.com/documents/insights/bsi-038-mind-the-gap-eh/?searchterm=mind%20the%20gap

Here's a GreenBuildingAdvisor article about attaching the furring strips which touches on fastening the siding as well:

http://www.greenbuildingadvisor.com/blogs/dept/musings/fastening-furring-strips-foam-sheathed-wall

Some people asking the same question:

http://www.greenbuildingadvisor.com/community/forum/green-building-techniques/14487/attaching-siding-houses-exterior-foam-insulation

http://www.greenbuildingadvisor.com/community/forum/green-building-techniques/15604/foam-penetrations-siding-attachment

http://www.greenbuildingadvisor.com/community/forum/energy-efficiency-and-durability/16782/installing-fiber-cement-siding-over-rigid-foa

http://www.greenbuildingadvisor.com/blogs/dept/qa-spotlight/how-combine-board-and-batten-siding-exterior-rigid-foam

Alan

[MushCreek]

Thanks, Alan! The Green Building Advisor article summed it up pretty well. It seems the experts feel 3/4" is enough, especially if using ring nails, which I would anyhow. My studs will be on 16" centers, so my fastening points will be 16" as well; much closer than the 24" max. I'm building in the woods in a relatively low wind area, plus the trees prevent much of the wind from reaching ground or house level. The house will have big overhangs, so the rain screen is probably overkill, but I'm a belt-and-suspenders kinda guy. I'm going to sheathe with taped Zip sheathing, AND tape the foam as well, so no water is getting in. I just like the idea that the rain screen will allow quicker drying in a climate that can be quite humid.

I do need to check with the inspector, though, to make sure they are going to be alright with my plans.