Method of wall framing

[cushionhead]

There seem to be two prominent methods of adding studs to walls, one that attaches wood (2x4, 2x3, etc) across the ribs, the other in-between the ribs. Below are two pics (not mine) that illustrate. It seems that the "in-between" method will give slightly more interior room but is perhaps a bit more work. Any pros and cons you can tell me about?

[FatBoySTL]

I'm fairly new to this, but I don't understand all the framing... What is the point of adding studs? Are you trying to make space for more insulation? If so, across the ribs is the only option. If not, don't bother with additional studs. As much as possible, arrange your cabinetry/furniture such that it can be bolted to the chair rail and ribs. Only add studs where you absolutely need to make an anchor point between ribs.

[Danjo]

Originally Posted by FatBoySTL

I'm fairly new to this, but I don't understand all the framing... What is the point of adding studs? Are you trying to make space for more insulation? If so, across the ribs is the only option. If not, don't bother with additional studs. As much as possible, arrange your cabinetry/furniture such that it can be bolted to the chair rail and ribs. Only add studs where you absolutely need to make an anchor point between ribs.

I think that it’s good to have wood to screw onto if you are paneling the walls.

There’s all sorts of ways to do the walls. I decided that I was willing to lose a few inches in width and just ran 2x2s over the existing aluminum panel and insulate that space.

[FatBoySTL]

Originally Posted by Danjo

I think that it’s good to have wood to screw onto if you are paneling the walls.

2" (presumably on each side) doesn't sound like much, but that's 5% of your total potential living space. Why is screwing wood to wood to metal better than cutting out the middle-man? I ask because I'm going to be doing my walls over the next 4 days, and I surely don't want to do this twice. Thanks!

[Danjo]

Originally Posted by FatBoySTL

2" (presumably on each side) doesn't sound like much, but that's 5% of your total potential living space. Why is screwing wood to wood to metal better than cutting out the middle-man? I ask because I'm going to be doing my walls over the next 4 days, and I surely don't want to do this twice. Thanks!

The fasteners used to connect wood to metal are big and not pretty. Once the 2x2 is screwed to the hat channel then a finish nailer can be used to attach panels or T&G to the 2x2.

3% wasted space.

You can put the “nailer” on the side of the hat channel and save the 3%

Use Teks wood-to-metal screws of the appropriate length

https://www.teksscrews.com/products/wood-to-metal

[BeNimble]

How about spraying insulation on the OUTSIDE of the walls, and then wood panel over the foam, now you gain space, and have a woodie. Because everyone loves wood, the more of it you have, the more people love it.

[musigenesis]

Putting insulation inside the cavities between the ribs compromises its effectiveness because of the extremely high thermal conductivity of steel (polystyrene insulation has a thermal conductivity of 0.03 while wood has a value of 0.15, five times worse; mild steel has a thermal conductivity of 54, which is 1800 times worse than polystyrene). In building construction it's estimated that insulation packed between metal studs is 30% to 70% less effective than unbroken material, so 1.5" XPS foam between the ribs of a bus will only be as effective as 1" or 0.5" XPS placed on top of the ribs.

In addition to ease of attachment as others have mentioned, placing wood furring strips on top of the ribs provides a thermal break between the steel ribs and the interior, and allows a greater overall thickness of insulation. It is probably better to run the furring strips front-to-back than directly aligned with the ribs (side-to-side) since this allows the thermal break to mostly be provided by insulation instead of wood (even wood is 5 times worse than XPS as a thermal conductor) and you don't have to worry about bending the furring strips to match the contours of the ribs.

The first pic you linked seems kind of weird, since it seems the insulation is packed between the ribs and then the wood is on top of that, which doesn't really accomplish anything, unless they later filled the gaps with more XPS foam board. There's also no reason for furring strips to be that massive.

[cushionhead]

Thanks all for your answers. I certainly agree on the size of the lumber used, doesn't need to be that big. Does it make sense to put sill plate gasket over each rib before installing the panels to create a thermal break? Or am I overthinking, lol

[musigenesis]

Originally Posted by cushionhead

Thanks all for your answers. I certainly agree on the size of the lumber used, doesn't need to be that big. Does it make sense to put sill plate gasket over each rib before installing the panels to create a thermal break? Or am I overthinking, lol

It's a lot better than nothing, but it's basically like 1/4" thick foam. If you use 3/4" instead, you triple the R-value over the ribs at a cost of just one additional inch of interior width.

[Sharee100]

Insulation. Insulation goes between studs. And you can't attach furniture to insulation. You need studs of some sort. And you are going to need insulation unless you always stay in places that are 72 degrees and sunny. I have seen a map for when and where to travel around the US and be in places that are 72 degrees historically when you pass through there.

[FatBoySTL]

Originally Posted by Sharee100

Insulation. Insulation goes between studs. And you can't attach furniture to insulation. You need studs of some sort. And you are going to need insulation unless you always stay in places that are 72 degrees and sunny. I have seen a map for when and where to travel around the US and be in places that are 72 degrees historically when you pass through there.

The bus came with studs... Monster metal ones and a beast of a chair rail. I can mount all the furniture to those and forego wood studs entirely (and that furniture will be far more secure). I see the argument for the wood furring over the metal to add an additional thermal break. I just don't know that it's worth it for my application. Every wall will have a cabinet or a couch over it. That creates an additional thermal barrier/ air gap, and this bus is so tiny, I need every bit of interior space I can get.

Unfortunately, I'm running out of days to test the finished product... July was hotter than hell here, but August has been quite sedate so far.

[Sharee100]

That's why I said whatever kind of studs you use, meaning metal already there or wooden ones. I also used the chair rail channels to secure my furniture. I purchased washers, wing nuts, and bolts. I secured my lower cabinets to wooden studs at the height of the lower edge of the windows. That way I have a ledge behind my counter to hold kitchen stuff.

[ACamper]

Originally Posted by cushionhead

There seem to be two prominent methods of adding studs to walls, one that attaches wood (2x4, 2x3, etc) across the ribs, the other in-between the ribs. Below are two pics (not mine) that illustrate. It seems that the "in-between" method will give slightly more interior room but is perhaps a bit more work. Any pros and cons you can tell me about?

A good part of my wall framing was to be able to secure stuff to the wall and to add insulation.

I secured a 2x4 at the window seal height and did 2x2s as "studs" under it. The 2x4 created a very solid platform to secure stuff to such as cabinets and appliances. The 2x2s were plenty to secure my 1/2 plywood walls, bottom portion of cabinets to and put 1.5" insulation between.

That's how I did mine it is stout and insulated.

[Sharee100]

Cushionhead...I like the photos you used. I used the first method just so I could straighten out my walls, too.