Question about plastering/skimming plasterboard

[Gypsy07]

I've removed a lot of ancient lath and plaster from various stud partition walls in my flat and I'm now about to start replacing it with plasterboard. The original plaster was about 2" thick. The plasterboard I'll be using is 12mm. The walls have to meet up with original cornice work all round the ceiling, and obviously that's going to be a discrepancy of almost 40mm in places. I'd prefer not to have to go around all the stud partitions with fiddly strips of wood to bring the level of the wall out to meet the cornicing, and anyway I would like walls thicker than 12mm plus a topcoat skim, for reasons of heat insulation, noise insulation, and also because I once fell against a plasterboard wall and went right through it!

So...

Can I put a thicker coat of plaster than just a skim onto plasterboard? As in, bonding a couple of cms thick like the way you'd plaster a brick wall? Is that even possible, or is plasterboard only designed to take a thin skim of topcoat?

Or should I put up two layers of plasterboard?

Apologies if either of those notions are dumb, but I've only ever lived in very old properties and this will be the first time I've ever used plasterboard. And I'm not sure exactly what you can and can't do with it!

[welsh brickie]

you can double board, or fix the first board to the studs. and use dry wall adhesive to bed out the second board to gain the required thickness.You can also use the adhesive to attach the board directly to brickwork

[30yearsinthegame]

the simplist way i would do it is to cut 10" square strips of plaster board. dot and dab those so yoou can dot and dab straight on top. have done this hundreds of times in repair work where a thicker wall is needed.

it saves dot and dabing twice . be sure to leave 24 hours between strips and full sheets.

good luck. let us know how you get on .

[Gypsy07]

you can double board, or fix the first board to the studs. and use dry wall adhesive to bed out the second board to gain the required thickness.You can also use the adhesive to attach the board directly to brickwork

So for doing that, you don't use screws on the second boards, is that right? Just the drywall adhesive? So how do you hold the board in place till it's set? A few nails till it's set, then remove them? Or is there some other way?

Thanks for your info btw.

[Gypsy07]

the simplist way i would do it is to cut 10" square strips of plaster board. dot and dab those so yoou can dot and dab straight on top. have done this hundreds of times in repair work where a thicker wall is needed.

it saves dot and dabing twice . be sure to leave 24 hours between strips and full sheets.

good luck. let us know how you get on .

Ah, I see what you mean. That would save me a lot of plasterboard if i was just using wee squares instead of full sheets. I think I'll give that a try on the stud partitions between rooms. I'm going to go for full double boarding on the stud uprights at the bottom of the sloped part of the ceilings as the backs of them is chilly roof space and I want the extra thickness for insulation.

Another couple of questions for you, if you don't mind:

How thick a skim of topcoat can you put onto plasterboard? I've got a couple of small bits in corners of a room that will need almost a centimetre. Is that do-able? I won't be doing that myself btw, I'm just wanting to check that I won't be giving some poor plasterer an impossible task!

And secondly, how difficult is it to get dot and dabbing right when the surface underneath is all uneven? I'm pretty competent at all other DIY stuff but I know plastering matters are a bit more tricky. I don't want to steam in and make a roaring Censored of it. I've never tried it before and NOTHING in this infernal place of mine is straight! The stud uprights aren't actually 'upright' at all and I can't move them as they're holding the roof up. The internal partitions are a bit better but the supposed 2x4s they're made from are anything from 3.75" to 4.25", and I can't remove and replace them as that would ruin the cornicing. Bah!