Should I put stud wall on top of floorboards?

[JP_]

About the renovate another room. Currently the room is split like this, with a small partition wall for a WC - it is a walk through room:

I plan to make this a separate room, without WC, like this:

The floorboards run top to bottom. I will be lifting the floor, cleaning out, changing the radiator, probably update electrics, insulating floor and external wall, replacing the window with smaller.

By coincidence, the distance from the external wall to new stud wall is 2.4m. There will be some rot under the floor in joists (some skirting is rotten, and had rot in all rooms on this wall). So I might just cut away the floorboards in the new room, leaving the corridor in tact, put in a new joist, and lay new 2.4m chipboards.

But, should I build the wall on top of the floorboards, or on the joists. Doing it on joists seems more sensible to me, but in my previous house, loft converts floored the area then built the walls on top. If I even need to lift the floor to access electrics, plumbing again, that would be much more work...

What is the best way though?

 

[oldbutnotdead]

Split the floorboards so the corridor is separate from the room, put the sole plate on the joists. Better for maintenance (and think about using floorboards rather than chipboard, they aren't that much more expensive) and better for reducing sound transmission from the corridor into the room.

 

[John D v2.0]

agreee with above, use plywood or timber floorboards, not chipboard (plywood is 30 quid a sheet so not breaking the bank)

Personally as a non builder I'd just build it on top of the floor boards if they're sound, I replaced all the old floor board with ply sheet in our bedroom before building the ensuite off the floor. If anything it improves the rigidity of the floor as a whole having a big sheet of plywood going across it all.

 

[mattylad]

Having come across floorboards that go under a stud wall several times and cursing - I'd suggest what oldbutnotdead(yet) said.
It would be betetr to be able to lift the floorboards in each room independently.

 

[JP_]

something like this
https://www.wickes.co.uk/Wickes-Non-Structural-Hardwood-Plywood---18mm-x-1220mm-x-2440mm/p/110037

not much more than green chipboard

 

[Notch7]

Split the floorboards so the corridor is separate from the room, put the sole plate on the joists.

that would be my default option too.

 

[John D v2.0]

something like this
https://www.wickes.co.uk/Wickes-Non-Structural-Hardwood-Plywood---18mm-x-1220mm-x-2440mm/p/110037

not much more than green chipboard

It does say "Wickes Non Structural Hardwood Plywood"
In reality it won't collapse but you should use a structural one for the floor.
I used this one which is cheaper anyway if you can get it delivered or pick up
https://www.builderdepot.co.uk/18mm...de-wbp-plywood-b-bb-2440mm-x-1220mm-8ft-x-4ft
"Structural plywood in internal dry conditions(EN 636-1S ) complying with EN 636"

 

[Bargain Bucket]

Should you not use T&G ?

 

[John D v2.0]

T&g produces a more stable surface at the edges and stops anyd relative movement at the edges. Technically you should put noggins under all the cut edges otherwise. To be honest i just left a mm between the sheets to stop them rubbing and creaking but it's a good point, thanks. If you were at 600 centres it may be more of an issue.
You can get t&g plywood but i didn't really look into that. Cheers
PS also t&g has a role in reducing draughts ord noise transfer so you can consider that in your decision too

 

[JP_]

Draughts and noise not an issue as will be insulating with solid boards, and on ground floor.
Might go the noggins route.