Plan to build a stud wall (with door) at the weekend, I’ve put one up previous using 4×2 (no door) but as space is a bit tighter where we’re planning to put the wall I wondered about using 3×2, like this:

http://www.wickes.co.uk/kiln-dried-sawn-softwood-47x75mmx24m/invt/107115/

Plus its a bit cheaper, should be fine right? and from a bit of reading a 115mm door liner?

Have a look at Wickes studwork timber. Its normally cheaper than sawn timber and is nicer to work with.
http://www.wickes.co.uk/timber/stud-work/icat/ststudwork/

Andy

I don’t know, but don’t ever ever buy timber from Wickes 🙂

I built a small one (about 30cm wider that the door frame) using CLS. Has been fine so far.

I saw that (no pun intended) but 38x63mm seems a bit weedy 😕 or maybe my previous wall was just over built…

The plasterboard adds a lot to the stiffness of a wall. Designed and built correctly they are plenty stiff enough. Have you ever seen the metal framing systems used nowadays? The individual steel members are pathetically flimsy until it is installed and boarded over.
Andy

You’ll be fine using 3″ x 2″.

Is the partition being boarded on both sides? If so, get ‘regularised’ timber which has been cut to a constant thickness (eg CLS, Ease-Edged, etc.) as this will make the boarding much easier.

Yes, boarded both sides, will look to get some cls cut wood.

Iv use 3×2 its fine

3×2 Cls 400 centres. Sole and head fixed to floor/ceiling respectively an one row of nogales down the middle.

As said. That proper studworwork timber is loads better to work with, plus it’s usually straighter & a lot cheaper.
My local merchants does two widths, I think the wider one works with a standard door casing. It did when I split my lounge in two.

I built a big 8′ x 2′ shelf unit in the garage from the stuff.

http://m.wickes.co.uk/Studwork-Timber-38x63mmx2-4m/p/107177

http://m.wickes.co.uk/Studwork-Timber-38x89mmx2-4m/p/107713