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-   -   How are walls set on floor frames without sheathing? (https://www.diychatroom.com/f19/how-walls-set-floor-frames-without-sheathing-444130/)

djenks 11-04-2016 07:33 AM

How are walls set on floor frames without sheathing?
 
I've been reading a lot about framing and watching videos. I've seen walls sitting on floors without sheathing. How is that done?

What I mean is, you have your floor and you have your header joists right. So on the two sides where there are header joists you can set the wall base plate over all the in between joists and nails then down i guess. But my question is what is supporting the walls as they sit on the other two rim joists.

I'm typing this out and I feel ridiculous. I'm basically asking how walls are supported when there is no sheathing on the floor. Two sides have joists the base plate can sit on. But the other two sides just have the single rim joist.

So for instance those floors where they use planks instead of sheathing. What are they tying their base plates to on the sides where there aren't joists to sit the wall on. Just the single thin side of the rim joist. Are they just putting multiple 2 x 6's or 2 x 4's there? A beam?

I'm seeing instances of walls raised and no sheathing down and wondering how that is done. Google isn't turning up much.

Thanks.

Bud9051 11-04-2016 07:49 AM

Re: How are walls set on floor frames without sheathing?
 
I' a bit old school, but the deck, floor joists and rim joists are all covered with the sheathing (sub-floor) and sometimes another layer to achieve the total required deck covering. BUT, the walls are not entirely supported by the flooring and must have cross braces added below where the walls are not supported by joists.

I can't imagine raising walls over floor joists without at least the sub-floor in place.

Also, with modern air sealing requirements the lack of a sub floor under those walls would make for a lot of air leaks.

Careful what you watch for videos.

Bud

djenks 11-04-2016 01:01 PM

Re: How are walls set on floor frames without sheathing?
 
Quote:

Originally Posted by Bud9051 (Post 3688346)
I' a bit old school, but the deck, floor joists and rim joists are all covered with the sheathing (sub-floor) and sometimes another layer to achieve the total required deck covering. BUT, the walls are not entirely supported by the flooring and must have cross braces added below where the walls are not supported by joists.

I can't imagine raising walls over floor joists without at least the sub-floor in place.

Also, with modern air sealing requirements the lack of a sub floor under those walls would make for a lot of air leaks.

Careful what you watch for videos.

Bud

Right but what about floors that aren't the floor of the structure? Like a loft floor?

Asfar as being careful, that's hat I'm doing by looking into this.

Bud9051 11-04-2016 03:05 PM

Re: How are walls set on floor frames without sheathing?
 
Well I can't picture what your loft is that wouldn't have a floor. But a subfloor does not support a wall. If the wall is parallel to the joists below and will be positioned inbetween or partially on the joists, then solid cross bracing should be installed every 16", max 24".

Bud

djenks 11-04-2016 03:43 PM

Re: How are walls set on floor frames without sheathing?
 
Quote:

Originally Posted by Bud9051 (Post 3689298)
But a subfloor does not support a wall.

Right, that is the point I am asking this. Because I know it doesn't support it so i am wondering how it is done.

I just used a loft floor as an example. Mostly because a lot of people lay planks using tongue and groove and just leave the underside exposed and it seemed like a good way to express what I meant.

Cross bracing makes sense. I'll read up on that topic. Thanks.

BigJim 11-04-2016 05:36 PM

Re: How are walls set on floor frames without sheathing?
 
If the walls are stood before the decking is installed, there will have to be a ton of nailers to nail the decking too when it is installed. If not there is going to be a lot of soft spots against the walls, especially on the end walls. I just can't feature why anyone would raise the walls before the decking is down.

djenks 11-04-2016 06:46 PM

Re: How are walls set on floor frames without sheathing?
 
Quote:

Originally Posted by BigJim (Post 3689842)
If the walls are stood before the decking is installed, there will have to be a ton of nailers to nail the decking too when it is installed. If not there is going to be a lot of soft spots against the walls, especially on the end walls. I just can't feature why anyone would raise the walls before the decking is down.

I don't either. That's what I'm trying to find out. I'm seeing people just put wood planks on bare floor joists and then leaving the underside exposed. It's odd.

AllanJ 11-04-2016 07:28 PM

Re: How are walls set on floor frames without sheathing?
 
Normally the subfloor (or decking) is put down first, out to the rim joists and building footprint.

(Walls perpendicular to the joists are supported by joists every 16 inches or so.)

Exterior walls parallel to the joists may receive all their support from the single outermost joist. Additional joists are added directly under an interior wall that happens to run parallel between two of the 16" spaced joists.

Cross bracing between joists usually takes the form of "X" bracing formed by thin metal or wood strips as opposed to (14-1/2") rectangular sections of 2x10 or 2x8 or whatever the joist size is.

Planks can make just as strong a subfloor as plywood.

djenks 11-04-2016 07:48 PM

Re: How are walls set on floor frames without sheathing?
 
@AllanJ , the single rim joist is enough to support it?

MTN REMODEL LLC 11-04-2016 07:54 PM

Re: How are walls set on floor frames without sheathing?
 
DJENKS...

Show us a picture of what you're refering to....

Most of today's framing is "platform" framing.... I'm wondering if you are refering to some "ballon" framing... which your answer would likely be that your loft is riding a ledger board.

Even in platform framing, your flooring can be a T&G finish grade dimensional board.... and if no ceiling is put in... you're looking at finished planking from below.

djenks 11-04-2016 09:05 PM

Re: How are walls set on floor frames without sheathing?
 
@MTN REMODEL LLC , No, not balloon framing. I didn't even think that was still used? Isn't that really outdated?

I'm reluctant to link a picture because this thread will turn into, "That specific example was done like this..."

Something kind of like I'm talking about would be like this I guess,

http://www.timberhavenloghomes.com/b...91902881_n.jpg

Reading around and kind of piecing things together I think I discovered two common method to not use decking / sheathing. It looks like what some people will do is one of these two things or a variation.

It is either, frame two wall sections, then two small wall sections, and put one small wall section on top of the other two. Then run the floor joists over the base plates of the top short wall sections and nail each one into a stud. Then frame a back wall the overall height and nail the back joist to the tall wall.

Or frame two wall sections, frame a floor complete with rim and header joists, set this floor section on top of your two wall, frame a tall wall the overall height for the end, then nail the back rim joist to the tall wall.

But I'm not sure if that would be enough support in the back. Just nailing the joist to the studs.

AllanJ 11-04-2016 10:18 PM

Re: How are walls set on floor frames without sheathing?
 
It is easier to assemble the wall frames for the next story when you have the decking (subfloor, sheathing, planks) down over the joists as a work surface.

Come to think of it, you have adequate strength and rigidity for the structure whether or not the decking is put down first and is sandwiched between the upright joist or rim joist and the plate of the next story wall framing.

The purpose of having two (sistered) joists is to reduce sagging of the joist in its middle But the joist is not going to sag when it (its bottom edge) is in full contact with the top of the foundation.

Now another use of sistering the rim joist is to keep the part of the plate not directly over a single rim joist from sagging by twisting (while the joist itself does not sag). This is usually not a problem except perhaps at a doorway where the rim joist may be sistered for just a few feet.

djenks 11-04-2016 10:36 PM

Re: How are walls set on floor frames without sheathing?
 
Quote:

Originally Posted by AllanJ (Post 3690698)
It is easier to assemble the wall frames for the next story when you have the decking (subfloor, sheathing, planks) down over the joists as a work surface.

Come to think of it, you have adequate strength and rigidity for the structure whether or not the decking is put down first and is sandwiched between the upright joist or rim joist and the plate of the next story wall framing.

The purpose of having two (sistered) joists is to reduce sagging of the joist in its middle But the joist is not going to sag when it (its bottom edge) is in full contact with the top of the foundation.

Now another use of sistering the rim joist is to keep the part of the plate not directly over a single rim joist from sagging by twisting (while the joist itself does not sag). This is usually not a problem except perhaps at a doorway where the rim joist may be sistered for just a few feet.

As far as what is easier for framing the wall section.. You can frame it below or even lay sheathing down temporarily..

I have read your post several times and still haven't been able to determine if you actually said anything.

All I took from it was that you said it is possible to set something on a single rim joist and it be enough support the wall and rafters above. Not sure why you brought up sistering and middle support out of no where either. No segue. I'm talking about exterior walls.

What are you actually saying? And which piece is relevant to what I am asking?

djenks 11-05-2016 10:19 PM

Re: How are walls set on floor frames without sheathing?
 
I'm assuming a common method would be something similar to this;

https://3dwarehouse.sketchup.com/mod...e-a0656feafecf


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