Stud wall over unreinforced slab

[WWilts]

Mesh reinforcement put into concrete slab wherever stud walls were anticipated. However, one spine wall (structural) was built a bit in the wrong place. To compensate for the resulting change in floor plan, a stud wall can be built but where the slab is not reinforced.

 

Foundation: Hardcore, slab.

Question: Is there an easy way to place some reinforcement under a timber stud wall? There will be some cabinets hung on it. 

Is it necessary to place reinforcement under partition walls?

 

[markc]

A stud wall does not impose much load, if you want to be doubly sure then double the sole plate, this will distribute the load across the length of the wall.

no slab work required … unless it’s about an inch thick which I hope not.

[WWilts]

24 minutes ago, markc said:

A stud wall does not impose much load, if you want to be doubly sure then double the sole plate, this will distribute the load across the length of the wall.

no slab work required … unless it’s about an inch thick which I hope not.

100mm concrete slab.
Just one sole plate on top of another? Or double width of sole plate?
Does hanging possibly loaded cabinets on the stud wall affect the requirements under the stud wall?

[Russell griffiths]

You need to put things in context, you are thinking that cabinets on the walls will increase the load, yes it will , but to what level. 

If you invited 4-5 friends over and you all stood shoulder to shoulder, let’s assume you all weigh 70kg, you wouldn’t panic  that you where going to fall through the floor. 

So put it in context, a spine wall carrying a roof load then that’s fairly serious, a stud wall to an kitchen, no matter how many cabinets you put on it is not going to impose that much. 

 

[markc]

41 minutes ago, WWilts said:

100mm concrete slab.
Just one sole plate on top of another? Or double width of sole plate?
Does hanging possibly loaded cabinets on the stud wall affect the requirements under the stud wall?

One on top of another with staggered joints, but on a 100mm slab there really is no need.

hanging cabinets on one side your most important loads are rotational wanting to pull the top of the wall over so make sure the header is screwed through into the joists above.

[WWilts]

Sole plate for stud walls on concrete slab or above celotex(100mm) & screed (65mm)?

[markc]

22 minutes ago, WWilts said:

Sole plate for stud walls on concrete slab or above celotex(100mm) & screed (65mm)?

No specific way better than the other here, screeders  would prefer you to stick it on top leaving them with a big open area to go at, you could also put in on top of celotex and use the screed to hold it in place or you could go down to slab but it’s always nicer to know the insulation is unbroken. If you go onto insulation then use double sole plate so the top of it sits proud of screed to fix bottom of PB and Skirts to.and the added piece of mind of better load distribution.

[nod]

Your worrying about nothing 

 

[saveasteading]

2 hours ago, markc said:

double the sole plate

Good plan.

A book-case will probably put more load down than your wall.

 

First jump up and down on the floor, and if you don't break it, neither will the stud wall.

 

One caveat though. if you build the stud very tight to the ceiling, and it is under joists, then it will take a lot of the upper floor loading. It may still be ok but better to leave a gap from stud to ceiling and fill with flexible material. There are details for this.

[WWilts]

1 hour ago, saveasteading said:

leave a gap from stud to ceiling and fill with flexible material

How then to tie the top plate to the ceiling joist or ceiling nogging? Just enough to fix it but not enough for it to receive the load

Edited September 29, 2021 by WWilts

[saveasteading]

2 minutes ago, WWilts said:

How then to tie the top plate to the ceiling joist or ceiling nogging

As  the floor will deflect as soon as furniture goes in, as well as with personal movement, it would load the screws and then the wall (or bend the screws)

 

The proper detail would be to fix an inverted channel to the ceiling, then build the wall within that but short of the top of the channel. You could fill the gap with foam rubber for sound.

That way there is no solid connection of wall to upper floor.

the channel could be a proprietary one, which would disappear under the plasterboard, or made of 2 Ls instead, to give you temporary access for building, or made of wooden battens, which would be ugly or perhaps could be hidden in the ceiling.  Search for 'deflection head'.

 

[markc]

@saveasteading good point, I didn’t consider the potential floor defection … I’m used to commercial construction. 
upper channel sounds good or even shanked screws in clearance holes in the top plate.

[saveasteading]

1 hour ago, markc said:

I’m used to commercial construction. 

It is a commercial detail, especially in clear span portal framed buildings where the deflection can be a lot.

 

WWilts, allow for 1/180 of the span. eg for 3.6m joist above, allow 20mm gap.

 

1 hour ago, markc said:

shanked screws in clearance holes

Sounds clever, but I will have to think about it.  You try it first.