OSB instead of studs for non-supporting walls?

[travelmodel]

Hi everyone,

I'm doing a DIYer creating an apartment in my basement. To fit a kitchen, I'm fighting for inches and I want to make some of my non-supporting walls as thin as possible. My plan is to use 5/8 inch OSB instead of 2x4 studs, then use 5/8 sheet rock on both sides (an OSB sandwich, fastened to floor and ceiling with L-brackets). When electrical is in the wall, I'd cut a channel in the OSB then put steel strips on both sides of the OSB to protect the line from nails and screws. For switches and outlets, The box will run all the way through both pieces of sheetrock, then I'd fasten a steel plate over the surface of the sheetrock and just mud it in so you don't see it. (Gaining a box that is a little more than 1.5 inches deep, which is enough for code, pretty sure).

I see a lot of situations where this type of wall may have advantages over a standard sheetrock + studs wall: 1) much thinner, allowing for more useable space, 2) Sound deadening, due to more material in the wall (air voids are also helpful for dampening vibration, but you can still do that by gluing 1/8 inch spacers to the OSB so that the sheetrock 1/8 inch away from the OSB). 3) Hanging cabinets and anything else - no need to find the stud because the whole wall is effectively a stud, 4) Very rigid - perhaps harder to bend than a standard wall, and I don't see why it would matter anyway if it's a non-supporting wall.

Is there anything in the building code that would prevent this type of super skinny wall?

 

[Beniah Naylor]

I would not hang cabinets on that, that wall will deflect in the middle and will not be able to support them. Otherwise could work in some instances.

 

[mtlogcabin]

Your interior wall should resist 5 PSF of lateral load. Instead of using 5/8 wood I would look into a Resilient Channel Product since the metal product provides more resistance to deflection than wood.

 

[ICE]

 

[travelmodel]

I would not hang cabinets on that, that wall will deflect in the middle and will not be able to support them. Otherwise could work in some instances.

I've got it supported in the middle so I don't think it will bend. I'm also doing this on other walls that won't have cabinets. My main question is whether the building code will allow such a wall.

 

[travelmodel]

Your interior wall should resist 5 PSF of lateral load. Instead of using 5/8 wood I would look into a Resilient Channel Product since the metal product provides more resistance to deflection than wood.

View attachment 13237

This is a very good idea for helping to resist bending, but do you know if such a wall is even allowed by code?

 

[Yankee Chronicler]

Use steel studs. Those furring channels are for furring, not framing. You can get steel studs as thin as 1-5/8". They use them in NYC for building apartment interiors, and they support kitchen cabinets.

Standards Metal Stud Sizes [With Size Chart]

Metal stud manufacturers are required to stamp the stud size and gauge on each product. For instance, ClarkDietrich labels 6-inch, 16-gauge studs with

iron-eng.com

 

[tmurray]

You can also use 2x4 sideways to build the wall. Just food for thought if you haven't thought about that approach.

 

[Beniah Naylor]

Are you doing this work under permit? It's really going to come down to whether your inspector is ok with it. I would contact them and have them look at a mock-up of what you are doing. The wall you are positing is not expressly forbidden, but it is not a prescriptive item that the code recognizes, so it would have to be permitted as an alternate method by the building department. I say build a mock-up because for me to approve it in my jurisdiction I would have to push on it to gauge deflection and stability.

The steel studs will certainly meet prescriptive code.

 

[Joe.B]

This is a very good idea for helping to resist bending, but do you know if such a wall is even allowed by code?

There's not going to be a clear code answer on this for you. Sorry. There are too many factors, and we would have to see this in relation to the whole project. What are the spaces on wither side of the wall? How much of the room does this divide up? Is there a door? All of this is really what code is going to address. For example, would this new partition affect natural light or ventilation? Code requires (generally) 8% worth of the floor area of a room in natural light, and 4%ventilation. Will you wall conflict with that? How about egress? Etc... I suggest that you confirm what version of code your project falls under (I assume some version of IRC) and review Chapter 6.

 

[travelmodel]

Are you doing this work under permit? It's really going to come down to whether your inspector is ok with it. I would contact them and have them look at a mock-up of what you are doing. The wall you are positing is not expressly forbidden, but it is not a prescriptive item that the code recognizes, so it would have to be permitted as an alternate method by the building department. I say build a mock-up because for me to approve it in my jurisdiction I would have to push on it to gauge deflection and stability.

The steel studs will certainly meet prescriptive code.

That is helpful. So it is not forbidden by code, but it is also not addressed by code. I do have a permit, so I'll ask the building department if they're ok with it as long as it doesn't deflect under expected loads.

 

[Yikes]

Think of it as furniture, like a Japanese shoji screen or the curtain around a hospital bed. It provides no function except visual privacy and space definition.
If that's all you need it for, then it might be approvable.
I say "might" because we don't know all of the purposes of this wall. For example, are you using this wall to meet either fire or sound separation requirements between the new apartment and the existing dwelling unit?

The 5 psf lateral force thing is an issue, if it's a permanent wall. In theory, a net can meet this requirement, but you probably want something that looks and acts like a wall.

Regarding sound deadening: yes heavier walls can tend to absorb sound energy. But your assembly is a diaphragm that also functions like a drum head.
Don't forget, plenty of stringed instruments rely on wood panels as a sound board. Intuitively, I do not think this will meet the minimum STC 50 requirement for dwelling unit separation walls.

Also, you might want to check out "Bamcore". It's similar in dimension to a very thick piece of plywood, but it's made out of laminated bamboo. It's stiff enough that they can make it vertically load bearing. I think they even even make it laminated with the same paper finish as gyp board. It probably has a lot less bending / deflection than your gyp/ply/gyp lamination.
https://www.bamcore.com/framing-systems

 

[Yankee Chronicler]

That is helpful. So it is not forbidden by code, but it is also not addressed by code. I do have a permit, so I'll ask the building department if they're ok with it as long as it doesn't deflect under expected loads.

If you have a permit, you have a permit to construct what is shown on the approved construction documents. To make a change, you will need to submit "amended construction documents" for review and approval.

 

[travelmodel]

Think of it as furniture, like a Japanese shoji screen or the curtain around a hospital bed. It provides no function except visual privacy and space definition.
If that's all you need it for, then it might be approvable.
I say "might" because we don't know all of the purposes of this wall. For example, are you using this wall to meet either fire or sound separation requirements between the new apartment and the existing dwelling unit?

The 5 psf lateral force thing is an issue, if it's a permanent wall. In theory, a net can meet this requirement, but you probably want something that looks and acts like a wall.

Regarding sound deadening: yes heavier walls can tend to absorb sound energy. But your assembly is a diaphragm that also functions like a drum head.
Don't forget, plenty of stringed instruments rely on wood panels as a sound board. Intuitively, I do not think this will meet the minimum STC 50 requirement for dwelling unit separation walls.

Also, you might want to check out "Bamcore". It's similar in dimension to a very thick piece of plywood, but it's made out of laminated bamboo. It's stiff enough that they can make it vertically load bearing. I think they even even make it laminated with the same paper finish as gyp board. It probably has a lot less bending / deflection than your gyp/ply/gyp lamination.
https://www.bamcore.com/framing-systems

I have built a test wall and I will check it for lateral strength. I hear you about the "drum" effect. To deal with this, I built the test wall as 2 1/8" = 5/8 sheetrock + 1/8 separator (basically a 1 inch rubber square placed every 12 inches) + 5/8 OSB + 1/8 separator + 5/8 sheetrock. I'm hoping the two air pockets knock down vibration from one side to the other. Regarding this 5 psf lateral force, do you know, how much deflection is allowed for such a test? The wall is supported with standard 2x4's where it comes together at a corner with another wall, and it feels super strong (strong as any 2x4 wall I've ever built). I can find a way to push it in the middle and divide the pounds of push by the SF of the panel. For an 8-ft tall wall, If it does bend a little, I'm wondering how much is too much? A millimeter? A centimeter? The bamcore wall looks really cool as a potential way of achieving a very thin wall that is also very strong and sound resistant.

 

[travelmodel]

If you have a permit, you have a permit to construct what is shown on the approved construction documents. To make a change, you will need to submit "amended construction documents" for review and approval.

That is exactly what they asked me to do - provide an "alternative construction methods" application. I'm optimistic.

 

[ICE]

If sound control is an objective it takes a mechanical break like resilient channel. I haven’t seen that in your posts so far.

 

[ICE]

If you have a permit, you have a permit to construct what is shown on the approved construction documents. To make a change, you will need to submit "amended construction documents" for review and approval.

You should not apply your jurisdictions’ strictures on the rest of Earth. I, for one, might make a field command decision and just say okay, let’s run with it.

 

[bill1952]

Reminds me a wall construction method I read about in Old House Journal. Basically a frame - perhaps 2x2 or taller at floor - stretch burlap - and 2 workers apply plaster - one each side working together.

 

[Yikes]

I have built a test wall and I will check it for lateral strength. I hear you about the "drum" effect. To deal with this, I built the test wall as 2 1/8" = 5/8 sheetrock + 1/8 separator (basically a 1 inch rubber square placed every 12 inches) + 5/8 OSB + 1/8 separator + 5/8 sheetrock. I'm hoping the two air pockets knock down vibration from one side to the other. Regarding this 5 psf lateral force, do you know, how much deflection is allowed for such a test? The wall is supported with standard 2x4's where it comes together at a corner with another wall, and it feels super strong (strong as any 2x4 wall I've ever built). I can find a way to push it in the middle and divide the pounds of push by the SF of the panel. For an 8-ft tall wall, If it does bend a little, I'm wondering how much is too much? A millimeter? A centimeter? The bamcore wall looks really cool as a potential way of achieving a very thin wall that is also very strong and sound resistant.

Travelmodel, can you please answer these questions to help us determine scope of code / structural application:
1. Is the wall separating one dwelling unit from the other? What is on the other side of this kitchen wall?
2. Is the wall separating conditioned (heated or cooled) space from unconditioned space?
3. You said the wall is "non-supporting" which I assume means it is not bearing the weight of any of the house/building above it - - is that correct?
4. What items might be attached to / hung off of the wall surface: upper cabinets? lower cabinets? Perhaps base cabinets can be attached in a way that will actually stiffen and brace the wall.
Anything hanging off the other side of the wall, such as closet rods, big screen TVs, bicycle hooks, etc. Will anyone attach exercise bands onto the wall, putting a horizontal pulling force on it?
5. Do you know if the building department considers the existing structure to be "Type V" (can be built out of wood and no other required fire ratings)
6. What kind of wiring will go inside the wall? NMC (Romex?) Flex metal conduit? Will you be cutting channels into the gyp board and/or plywood in order to hide the wiring, and if so, will those channels essentially break up this large piece of plywood into a narrower strip of wood?
7. Are you planning on installing any doors into this 2 1/8" assembly?
8. When the building official says to consider using the alternate means/methods, does he state any performance criteria other than the previously mentioned 5 psf?

I don't know of any code limitations regarding maximum deflection of a nonloadbearing wall. As mentioned in a previous post, a hypothetical net (which has tremendous flexibility) might theoretically meet this code requirement. so if you are OK with 1" deflection, I don't think the code will have much to say about it.

One last thought: Have you seen any similar construction on recreational vehicles, where a plywood panel / divider "wall" supports cabinets?
RVs are not governed by the building code, but it could provide anecdotal evidence / support to help make your case.

In the end, if the only remaining code issue is the typical 5lbs. lateral support, it may be easier (instead of getting engineered calcs) to just to build the wall the way you want as a "mockup" and the push on it for a real-world test result / demonstration for the building official.