Studs 24" On Center?

[ToolsRCool]

New detached garage build this year. Going to be 2x6 exterior walls. Considering to use larger rafter boards and spaced at 24" on-center, vs smaller boards at 16" on-center. Larger rafter boards will allow for more insulation per cavity, and may end up as lower total material cost, still have to run the numbers.

But, in doing so, it then begs the question: If rafters are being spaced @ 24" OC, should I be doing the same with the 2x6 wall studs they will sit above? Will still be a top double plate on the wall, but are there any advantages or disadvantages of 24" OC stud spacing (vs 16" OC) I am not considering? Prelim research shows it may be permissible, have to look deeper into that as well, but I think I can make a lighter wall to stand up, lower material cost, and stronger overal structure if all done @ 24" OC, rafter and stud spacing.

Thoughts? Beat it up...

 

[The Cobbler]

unless the cost savings is considerable, i would do 16"o/c . there's benefits to having 16" O/C studs , like when hanging heavy stuff like cabinets
when I framed & insulated my basement walls it would have actually cost more to do 24" centers due to higher insulation costs .

 

[Kaizen]

Yea not going to save much. For a 16 foot wall you save 3 boards. I would still do 2x6 exteriour walls so you can do more insulation.
roof trusses are normally 2' on center but double top plate spreads load so either should be allowable if local code accepts it

 

[Hilltopmasonry]

Honestly you need to have an architect or engineer let you know that info

 

[mike93lx]

No need for a double top plate if you do 24oc for all of it.

I am building a 16x16 right now and did 2x6 24oc for the walls and trusses at 24oc. Material savings is basically nil. Main benefits would be insulation and less thermal bridging

 

[WisJim]

I would do 24" oc for studs and rafters. It's plenty strong and gives space for more insulation. Lots of studying on stud spacing has been done in the last 40+ years and there are good arguments for the wider spacing.

 

[ToolsRCool]

Thanks for all the replies, good points on each side. It all lines up with the little I have learned on it so far, so good I did not seemingly miss anything.

I did not consider to factor in insulation cost for a 16" 2x6 wall cavity (R-23 batt) vs 24", on a $/area basis. Will check that.

Understanding on double top plates was same, that is really for when rafters or trusses and such land in between studs. 24" OC for all really seems to make sense from this perspective.

This then goes even a little more sideways, because I am reading up on installation manuals for cement board T1-11 (Hardi-board), and it says their preference is to double up studs on every 4' mark, so the end flange of each T1-11 fiberboard sheet can rest on a full 3.5" board edge vs half of that, and not have the edge crumble when taking a nail. I get it. So, part of where this was going, was to do 24" spacing, and doubles ever other. So, probably even more total studs than 16" OC spacing, but nice double-width edge studs at siding sheet seams, yet not as many total studs and weight as if trying to do the same @ 16" OC and doubles @ 48".

Jury still out on all of it, just thinking out loud. Thanks for all input.

 

[BrandonV]

Prefer 16" on center just for things that come out of the box designed for that (like TV mounts).

 

[Dagny]

I like wiring them better but would go 16 unless you sheet inside with 3/4 plywood.

 

[Firebrick43]

You could do 2x8 top/bottom plate and do off set 2x4 studs on 24" centers with two layers of R13. There will be a stud actually ever 12" but off set from each other. Much better insulation, minimal thermal bridging, and strong. Energy cost are only going to go up.

 

[larry4406]

When my company upgraded our walls to 2x6 for improved insulation, the bean counter contracts manager decided to save money by going to 24" on center wall studs. The result is that the OSB sheathing was wavy with only one stud in the middle of the 4' width. The wavy sheathing telegraphed thru to the siding.

After many repairs to eliminate the wavy sheathing, we went back to 16" on center still with 2x6 studs and double top plate.

With 16" on center, there are 2 studs within the field of the sheet and you get a much straighter wall.

 

[billconner]

Depends on sheathing. 5/8 or 3/4 is my preference.

 

[Copymutt]

Code here required lots of blocking for 24” oc. Still looks good after 29 years.

 

[mike93lx]

Code here required lots of blocking for 24” oc. Still looks good after 29 years.

What kind of blocking? For sheathing?

I went vertical to avoid needing to add blocking for joints

 

[CraigStu]

For the siding you could sister on a 2x2 to the 2x6. But then that would require some special stud location and could be a pain if you are building walls in 12 or 16 ft sections.

 

[Rusted Nut]

I would not do 24” centers if you are using OSB sheathing, it may warp. 1/2” plywood is fine though.

 

[billconner]

I took advantage of the 24" o.c. and used windows with a rough opening of 22". No headers, jack's or cripples. Material and labor savings. But as others point out, no 1/2" sheathing. At least 5/8 but would prefer 3/4. (I used 1 by rough sawn - cost less than 1/2" OSB and much stronger.)

If your just using 2x6 for better insulation, consider a Mooney wall - 2x4 16" o.c. on exterior and horizontal two-bys on interior. Breaks the conductive loss, fairly economical.

 

[Copymutt]

What kind of blocking? For sheathing?

I went vertical to avoid needing to add blocking for joints

Yes and racking.

 

[carlaisle]

The only meaningful improvement from the wide spaced studs is in the reduced thermal bridging. The single top plate is fine from a structural standpoint, but you must make sure the rafters/trusses end up exactly on top of the studs. You'd be hard pressed to save $500 in materials and the strength and utility of your structure will be permanently decreased for it. Whatever path you take to stuff more insulation into the ceiling will pay dividends.

 

[billconner]

Yes and racking.

footnote a. to IRC table 602.3(6)

 

[u2slow]

What's the wall height? Truss and stud spacing don't have to match. Mine don't.

 

[ToolsRCool]

What's the wall height? Truss and stud spacing don't have to match. Mine don't.

10' side wall height. Will be stick built rafters with ridge beam for cathedral ceiling on 2nd floor. Understood on alignment, but would presume to be stronger if so. Double top plates required if not in alignment.

 

[u2slow]

10' side wall height. Will be stick built rafters with ridge beam for cathedral ceiling on 2nd floor. Understood on alignment, but would presume to be stronger if so. Double top plates required if not in alignment.

I needed double top plates regardless. Custom truss arrangement to give me 19.5' ceiling height and 12' clearance under flanking lean-to's.

 

[Hank11]

If using sheet Hardiboard, I would use 16” spacing to be sure the walls do not look wavy.

 

[Beauregard]

Another benefit of the double top plate, to me anyway, is it makes for stronger corners when overlapped.

 

[Hank11]

The additional cost of material and labor for a double top plate is almost negligible.

 

[billconner]

I tend to agree the double top plate solves problems rather than creating them.

 

[CraigStu]

I tend to agree the double top plate solves problems rather than creating them.

I agree. In addition to corners Beauregard mentioned, how else to join 12, 16, or 20ft wall sections.

 

[mike93lx]

I agree. In addition to corners Beauregard mentioned, how else to join 12, 16, or 20ft wall sections.

Corners can be done with strapping as well and it's just as strong. For longer walls, you can stagger top and bottom plates and have a stud land on the joint.

A double top plate makes it easier but isn't necessary.

 

[cannuck]

You could do 2x8 top/bottom plate and do off set 2x4 studs on 24" centers with two layers of R13. There will be a stud actually ever 12" but off set from each other. Much better insulation, minimal thermal bridging, and strong. Energy cost are only going to go up.

I would suggest doing this with interior 2x4 turned 90 degrees to accommodate cement board joints.

 

[imma_stocker]

DR Horton built my home with 2x6 at 24" OC. Good for insulation and building fast as possible (less cutting, less fasteners, etc), bad when you go to hang a TV wall mount designed for 16" OC studs.

 

[ToolsRCool]

All great points, some interesting ideas as well, thanks.

 

[NUTTSGT]

If you're using Hardi, then make sure you build to their spec.

I built my addition 24"OC with 2x6 studs. I put 7/16" or 1/2" ZIP on the outside and then sheathed the interior with 1/2" plywood. I think my walls stayed straight.

I'd do the double top plate for the simple fact of joining wall sections. Required, maybe not, but I'll beat the minimum code requirement for a few extra dollars spent.


Just remember if you go with double top plate, to nail above the studs and not in the middle of a wall cavity. Drill holes for wiring and hit a nail you'll understand.

 

[Joemctag]

Another benefit of the double top plate, to me anyway, is it makes for stronger corners when overlapped.

And, in fact, anywhere there’s a splice in the top plate.

 

[Dragfluid]

Several folks mentioned "cutting down thermal bridging". Cut it down to ZERO by adding 1/2" POLYISO on the inside, under whatever you're sheeting the interior with. On the good shop that I moved away from, I used 1". It could be -15 outside and you could lay your palm on the drywall and it was room temperature. Also, you mentioned R23 in the walls. So apparently, you're using mineral wool? Have you looked into dense pack cellulose? At 5.5", you would have R22 at probably half the cost. Just another option for you.
Look at my old build thread with the link that's still down there. v

 

[cannuck]

I dealt with thermal bridging on our 2x6 wall stick built house by adding 1.5" polyisocyanurate board on top of sheathing. Made a HUGE difference especially in corners where double top plate and mullti studs were cut off from ******* away heat enough to frost the walls before retrofitting.

 

[ATC]

Looks like OP is in Michigan. I hope you are factoring in the correct snow load figures for 24" centers vs. 16"

I would do 16" centers for everything. It's "standard" and will most likely make everything easier down the road (mounting things to the walls/studs).

 

[billconner]

2x6 24 on center is more support than 2x4 16 on center, so I wouldn't worry about snow load.

Hanging things on the wall may be an issue but not insurmountable and also dependent on interior wall surface. Plywood or OSB would seem easy for hanging. Drywall present some greater challenges but it would be 5/8 for 24 on center. Better energy performance and faster construction would outweigh the hanging on wall issues for me.

 

[Jim greengo]

I'd do everything on 16" centers myself,including the roof.
I've walked on enough of other people's sketchy 24 on center roofs around the midwest,no thanks.

 

[mike93lx]

I'd do everything on 16" centers myself,including the roof.
I've walked on enough of other people's sketchy 24 on center roofs around the midwest,no thanks.

LVL studs, 12OC is the only way to do it