How to extend a brick wall with plasterboard/drywall?

If it's only 6ft wide then I wouldn't bother shrinking it down with plasterboard first, fit a frame and 2 or 3 sliding doors.
Otherwise if you really want to go with putting plasterboard and doors, just measure from the existing wall back 12.5mm or whatever the thickness of plasterboard being used and attach the framework timber to that mark.

 

Phil - tee-hee .

T100, I'm not sure of what your current alcove looks like - in your drawing above, is the cupboard you've drawn there what you want it to end up like, or what you have now?

Anyways, that doesn't matter. You want to know how to join a p'boarded stud wall to block?

Ok, your block wall will be plastered? That will consist of a thicker bonding coat (ooh, up to around 10mm thick?) and a finishing 'skim' coat 2 to 3mm thick.

To continue your stud wall from this plastered block wall, you need to place the first vertical stud securely to this block wall so's it can't move (plugs and screws and even PVA it before you screw it on tight), and this stud will have to be stepped in from the finished surface of the plaster by this amount: thickness of p'board to be used (9mm or 12.5mm, hopefully the latter) and 2-3mm for a finishing skim. So by about 15mm in total.

Then you build the stud wall and screw on your p'board, butting it up tight against the end of the block wall. The front surface of the p'board will now be stepped in by 2-3mm from the finished surface of the block wall as mentioned previously.

You then use a craft knife to score a casual vertical line into the skim on the blocks (into the 2-3mm skim layer only) around a couple of inches along from the studwork. Use a chisel or similar to scrape away that 2"-ish wide layer of skim.

That 2" wide strip will now be roughly the same level as the p'board on the studwork. PVA your p'board scrim tape (or use whatever adhesive is recommended) across the stud and the block - on inch on either.

When you - or your plasterer - now skims your new stud wall, they will blend it into the block wall. The scrim should prevent a crack appearing later on. Without scrim tape, a crack will almost certainly appear...

 

Your drawing suggests that one end is against a straight wall!
I'd build that end out 12" forgetting about making good straight joints at the 'store' end wall.
Start the store end wall with your liner, across the top and meeting stud wall at the 12" stud end(sizes are approximate, you will know the exact stuff). Plasterboard the 12" end, archtrave the liner, quick skim down the stud, done? Use the 12" recess for some shelves?

Mr. HandyAndy - Really

 

D'oh - I didn't realise T100 meant that gap where the arrowhead was pointing .

As before, T100; Screw that first vertical stud to the corner end of the existing built-in cupboard, stepping it back the 15mm mentioned before. Plug and screw so's it can't move. PVA it to the wall at the same time too - a good wipe doing the mating surfaces, and wipe away with a damp cloth anything exuded after screwing. Ooh-er, missus. (You want zero movement there, or you risk forming cracks.)

At the far end, plug, glue and screw as well.

Build the rest of your framework in between, board it with screws, and then trim that 2" wide band of 'skim' from the corner of the existing store so's you can lay your scrim tape there. You probably won't have to do this at the other end as I think it's much less likely to hairline crack there, and it certainly won't be as noticeable. Do DO brush a good line of PVA into where the stud and that wall touch at the front - if there's a gap there, say from using CLS which is rounded timber - then get yer PVA in there to thoroughly bond that stud to the wall.

Mind you, it isn't just movement that cause hairline cracks, it's also that timber and concrete have different expansion rates, timber especially also reacting to humidity levels. So in theory you should also scrim-tape against the far wall, but I think I'd personally try and get away with it (I mean, what's decorator's filler for, eh?)

 

T100, the first option is a 'doer' for someone prepared to work methodically and learn along the way even tho' he may not have much current DIY experience - at the end he will be flushed with excitement, and the wall will hopefully be flush too.

And it won't cost too much to do.

The second option will actually cost you a small fortune, and almost certainly end up looking hellish...

If you use, say, walnut-veneered plywood/chipboard (as you should if you want the finish to look decent), then it'll be an absolute 'mare to cut accurately, each sheet will be pretty pricey to start with, it'll be hard to get a professional finish, and you will almost certainly end up with unpleasing door gaps and shut lines.

That option is for experienced DIYers only. (I consider myself to be one of them, but - let me think now - nope - there is nothing on this planet that would compel me to try what's in that picture...)

A flush cupboard with doors is the way to go. An easy - and possibly more practical too - way to fit doors is to use 'folding' gear. Ie: your two doors hinge in t'middle and are hinged to the wall at one end only. You pull in the middle, and they come out, fold in the middle between them, and go flat back against one side. You can buy the gear for this and use them on ordinary doors - so it can match your main bedroom door if it's a 'nice' one eg panelled.

 

pssssst linky

 

yep, they are very good, not cheap thou

 

Tsk - "tho'"

 

practise what you preach, or in your words

any practise what you preach

 

I would have started with a capital.