Framing and Zip R Vertical Sheathing
grandpajay
| Posted in General Questions on
Hi folks
I am going to be building a single story house with 8’ exterior walls. I was wondering if I could use 2×4 walls at 24” centers with 1.5” zip r vertical sheathing. I would use double 2×4’s at each side for better nailing and shear strength of the zip and a single in the middle. I think it would be strong and would use spider or mineral wool. The house would be 30 miles from the coast in central n.c.
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In general, 2x4s 24" OC is fine for single story homes, and the insulation will meet minimums for zone 3.
I am not entirely sure of what you mean by "double 2×4’s at each side... and a single in the middle" though. Are you referring to a double top and bottom plates? If so, I'm not sure it would help (especially the double bottom plate), but it definitely wouldn't hurt. Much more important is making sure you have appropriate anchoring and ties for you walls/roof, using a hipped roof design, and following the proper guidelines for windows and doors.
Hi aedi
What I would like to do is install the zip r vertically. In framing the studs at 24” centers , every other stud would be doubled at the vertical edge to provide a whole stud to nail into instead of trying to hit just 3/4”of the stud. I have been reading about shear panels and and hold downs in hurricane country and they recommend 4x4 posts every 4’ instead of a single stud. Doubling a 2x4 would be cheaper. I plan on using more of my budget in attic insulation and windows. Setting studs at 24” would give better insulation and use less hurricane brackets. I’m not worried about wavy drywall so much as having a good wall fairly cheap. I’ve looked at Mooney walls and that may be more expensive and time consuming.
grandpajay: Nice to see somebody independently raise the topic of a nontraditional building element that's showing up in my sketches.
A seismic design document for California that I read recommends it, not so much for strength, as for much enhanced reliability of attaching the sheathing; It points at sheathing stud misses as a significant cause of structural collapses in an earthquake.
And google says apparently it's found its way into the IBC and NDS:
"Framing at adjoining panel edges shall be 3" nominal or wider, and nails at all panel edges shall be staggered." This means that where 2" nail spacing is spec'd, you can use 2x edges where the sheathing is NOT spliced, but where a splice occurs, there must be 3x, or larger backing. The NDS (the wood bible referenced by the IBC) allows 2, 2x nailed together in lieu of 3x."
My observation #1 is: Typically when people describe advanced framing / OVE, they talk about going from 2x4 16" OC to 2x6 24" OC. I'm unclear whether doubled 2x4 achieves rigidity in the same dimension as you need, particularly if you are aiming not at code-minimum, but at hurricane safety.
My observation #2 is: If my thinking is sound about how FEA heat transfer works, doubling studs enhances thermal bridging significantly over single studs 12" OC, and even aside from that, provides a significant opportunity to screw up the air barrier if that seam doesn't get resiliently covered. My designs right now use two plywood-sheathed taped walls with the sheathing between them, and the studs offset, to help with both issues.
My question #3 is: How is the roof attached and vented? With only 8ft on the exterior, how do you fit in attic insulation?
Hi bud I ate
Really appreciate your knowledge. From what I read most shear stress is always on panel edges so stud spacing at 16 or 24 isn’t so important. The zip r is not recommended for uplift so tie downs are still needed. I would probably still diagonally brace corners for peace of mind. I agree, so many nails are missed on edges, especially thick panels like zip. Also some inspectors may fail you for having nails so close together that it splits the stud. Thanks again. Jays
Burninate
I want to use trusses at 2’ centers placed directly over studs with tie downs. Some trusses would be cambered to a 10’ height for great room and kitchen. I want to insulate over the trusses with loose fill, with soffit and ridge vents. It’s only 1400 square feet and I want to use 2 mini splits for heating and cooling. Your right about the thermal bridge, but the zip r will help. Like I say I’m more interested in ceiling insulation and windows. North Carolina is a warm climate so a super thick wall may not be needed. Sorry about your name spelling on the previous post. Jay. P.s. raised heel trusses will be used.
One source says: "... all framing members receiving edge nailing from abutting panels shall not be less than a single 3-inch nominal member."
"single" could be a problem. But maybe with some combination of glue, screws and brackets connecting them, 2 2x4s would be equivalent.
Make sure to look at the Code report for the Zip Panels to get all the information for the structural design. See the shearwall aspect ratio & deflection with the zipR foam panels.
Also this is a base document for the code on residential wood frame construction from https://awc.org/codes-standards/publications/wfcm-2018 it will guide you on how to prescriptively engineer a residential structure. You can view it for free.
3x lumber at panel joints, 3x sill plates,5/8" anchor bolts, square plate washers, holddowns and fully blocked shear walls have been common here in California since the 1997 code.
for wind design see https://fortifiedhome.org/ for additional steps
It might be money well spent to have your plans engineered so you get the state of the art details and professional advise on how it should be done to meet the modern codes.
Hello,
I am working on a tiny house build. 10' walls and 9' low slope shed roof. I would like to frame with 2x4 walls that will be 124" long on 24" centers to save some weight. Any recommendations for this? Is this advisable or risky?
thanks, Alex
Alex, I believe that Randy Jones at Incredible Tiny House builds his walls that way. He has a YouTube channel. I am considering Sips panels to save weight and avoid thermal bridging on a Tiny house build
Dave
Bringing this thread back to get feedback on a two-story house I'm planning. I'm aiming for Passive levels of performance, located in CZ 3A.
I'm waffling between:
- Double stud with a bearing outer wall, 2x4 24" OC, 10.5" thick
- Or something like a Bonfiglioli wall with 2x8s, 24" OC
House has 9'6" first floor, second floor will be about 13" tall at gable ends, which will be "balloon framed" if I have that term correct.
The Bonfiglioli is a little less expensive in lumber costs, but seems a little fussier to build.
Changing the double stud design to a 2x6 bearing wall would make it even costlier, so not really considering that. I'll finalize everything with an engineer, but is 2x4 just not an option?
FYI, the strict definition of balloon framing is where the exterior wall studs rise the entire height of the building (floor plate to rafter plate) and are notched for a ledger that the joists rest on.
Gotcha, yeah, so not balloon frame, just second floor studs continuous to roof on gable ends.
How about if you use the 6x or 8x top & bottom plates, and then for vertical use 2x4's at 12" oc but staggered, so every 24" there is a 2x4 flush with the interior wall, and offset 12", every 24" there is a 2x4 flush with the exterior wall?
I found that although 2x4's at 12" oc is more board feet than 2x6's at 24" oc, the 2x4's cost significantly less than the 2x6's. Also this gives you the advantage of a thermal break at each of the framing members. Of course at the doors & windows you have to use a member that is the same thickness as your top & bottom plate so you have something to nail your interior and exterior sheathing /gyp to, but at least in between you don't have a thermal bridge.
Do I understand that you will be balloon framing a 2 storey house with high ceilings? The detail you provided shows platform framing, which is now standard.
You can build structural walls with 2x4, but your engineer may start getting uncomfortable when the walls get over a certain height. But there are possible solutions. Walls detailed as shear walls, rigid diaphragm on the ceiling, etc.
No, I think my description was flawed. Platform framed, but second floor studs will be continuous to the roof on the gable ends.
Thanks for the reply, I’ll see if I can stick with this double stud layout. Already planning to use 19/32 plywood sheathing, so that should help a little with shear?
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The WFCM prescriptive .pdf for a building surviving 130 MPH winds in exposure category C (basically out on the open plains), allows for 2x4 @ 24" O.C. for a maximum stud height of 9'5". Except at the first 4' of any exterior wall corner, where stud spacing should be spaced at least 80% closer than 24" O.C.
https://www.awc.org/pdf/codes-standards/publications/wfcm/AWC-WFCM2012-HWG130C-1511.pdf
This is assuming a building with a 20' tributary length of roof load.
The 2015 IRC Chapter 6, table 602.3(5) allows for a laterally unsupported stud height of 10'. The only exception is if there is a habitable attic, then the roof span is limited to 32'.
2x4 studs 24"o.c. is fine for single story, but not to support a floor above. Must go to 2x4 16" o.c. or 2x6 24" o.c. for a two story building.