Hi, I'm going to have a stab at undercoating a small internal wall. The old plaster was completely blown, so I've taken it all back to brick. My (naive) questions are:

1) Am I better off with "Flatness guides" (from Wickes) or timber battens? I can't really visualise "timber battens", so if this is the prefered method, can someone please describe them? I assume you can't buy them? I know the difference between the two is that the guides are left in the plaster and the battens are removed.

2) Would the only reason for having two lots of undercoat is if the surface is really uneven? I.e. is it not standard if the walls are pretty even?

3) If you put corner angle beads on at the same time as battens / flatness guides, then I assume that the undercoat covers the beads completely? Is this okay for someone who then puts on a finishing skim (i.e. no guide)?

4) I have corners which are not a standard 90 degree angle. What happens here in terms of corner beads?

5) Here's a question - if you just put up plasterboard, you still have to put corner re-inforcements on it. If this is the case, can you just finish plaster over this, presumably as they would be sitting nearer the wall than when undercoating a wall (as they would then be the same distance from the wall as the battens / guides)?

Thanks for your help. I recognise these might be stupid questions, but you've got to start somewhere.

Andrew

1. never heard of flatness guides but they sound like a good idea for beginers.

2. Two coats are often used when you are trying to match up with existing plaster, that is really thick and can't be applied in one go because it drops off with the weight.

3. You would normally set the angle beads into the undercoat, but do not cover them, only cover them with finishing plaster.

4. You can manipulate the beads or fit them so that the corners become square, before plastering the finish coat.

5. Not sure exactly what you mean here but you can direct bond the plasterboard and so do not need any battens, this is much easier than plastering and even a novice can get good results.

check out this section- http://www.ultimatehandyman.co.uk/PLASTERING_CENTRE.htm

look at direct bond method, angle beading and then skimming. You should get most of the answers you need there.

p.s I am not a plasterer but have done a fair bit, I think -dj- is a professional and may advise you better.

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Nottingham carpenter

Thanks for your answers. You are right about my 5th question - it didn't make sense! What I meant was as plasterboard doesn't need an undercoat, will finish plaster simply get skimmed over the corner beads? I assume so, as the corner beads would be sitting much nearer the plasterboard and so the finish depth would not have to be any greater than normal.

You say DJ is a professional plasterer; how do I go about contacting him? Do I just hope he reads my post or do I have to put out some sort of bait?

I have thought of some more questions to add to the list:

1) Can the undercoat be left for any amount of time before the finish plaster (days, weeks), or does it have to be done the same day?

2) Does the brickwork have to be pva'd prior to the undercoat?

3) Does the undercoat have to be scratched / devilled prior to the finish coat, or is that just for when another layer of undercoat is added?

Many thanks for your help.

Andrew

the only bait i accept is big brown envelopes stuffed full of 50's

you have got a lot of questions here so i'll try to get through them the best i can, if you need any more help then please don't hesitate to ask!!

your first post.

1) flatness guides i have never used so i can't comment on them, a baton is simply a piece of wood 1in by half in fixed to the wall as a guide, then removed before skimming.

2) yes you are correct

3)your angle bead should protrude from the battons, but only by a couple of mill.

4) unless there is a massive difference from the 90 degree then a normal bead should do, or even work off a stop bead!!

5) angle beads are for using with backing coat, skim beads are for using on plasterboard corners.

...............................................................................................
now for answers to post 2.....

1) by rights you should skim the same day otherwise it is too dry to skim, if you really do have to leave it then pva it first making sure you seal the whole area missing nothing.

2)no, usually a good wetting will suffice. however, i think that as you seem to be very new at this i would recommend you did pva it first, 4/1 should do.

3) yes the under coat should be devilled to accept the skim, however if you needed to do two undercoats that would need scratching too.

hope i covered most things there for you. anything else then just shout!!

Hi Andrew,

I'm not a pro plasterer but have done a fair bit on my own houses.

If you use plasterboard then you do not need to use undercoat plaster, the easiest way to fix it is with the direct bond method

Then fix the corner beads
fix angle beading

Then
skim with plaster

If you choose to undercoat then you can leave it as long as you like but scratching the undercoat is a good idea.

I would PVA the wall first to prevent the bricks from sucking out all of the moisture from the plaster.

You don't need to PVA between the undercoat and skim coat as long as you ensure that you wet the undercoat enough first. But I don't think it will cause problems if you did use PVA.


Hope this helps

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DIY | Donnas dream house

It took me ages with the above post and -dj- beat me to it

Thanks -dj-

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DIY | Donnas dream house

like busses eh!!

Thanks, you guys respond fast and are very helpful. It's much appreciated.

Right, with all your answers in tow, I only have a few more questions! :

1) I've read somewhere that you don't have to wait for the PVA to dry before plastering on it. Is this correct?

2) Is there a definitive guide to using battens anywhere? I know there's a piece in the plastering centre about undercoating, I was just wondering whether there is any other advice order screwing them to the wall and making sure they are plumb and in line? No tricks?

3) Internal brickwork = thistle browning?

4) Trowels - should you use a different one for undercoat and finish? Also, is it true you have to "break in" a trowel (http://www.goldtrowel.org/plastering-tips.htm), and if so, does this link do it justice? Will any trowel do for undercoating work? What is a good trowel?

Many thanks once again. I can't wait to get cracking on my wall. If the undercoat goes well, then I might pluck up the courage and ruin it by buying a bag of multifinish!

All the best,

Andrew

1. That is correct, although if you are doing a large wall it will probably of dried before you are ready to plaster it.

2. Don't think there is a definative guide, just fasten them to the wall with a suitable fastener and use a large spirit level to ensure they are flat, you may need to pack some of the grounds away from the wall.

3. I once tried browning and it went everywhere bar the wall, Bonding is much easier to use in my opinion.

4. I use the same trowel, they do need breaking in but you can buy them ready broke in, but not sure of price or how good they are!

Good luck

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DIY | Donnas dream house

to be honest, i don't see the reason you have to use browning or bonding, it would be far easier for you to stick plasterboards on with dri-wall adhesive then just skim that.

as for a trowel, marshaltown do a nice line with some worn in ones, i use a 13in stainless mostly. if you got one and looked after it then it would last you a lifetime.

The rest of the room is proper plaster, and I didn't fancy one part being plasterboard (although I did think about it). Besides, I thought starting the old way would give me a decent start in plastering (I'll have plenty of opportunities to use plasterboard in the future, and plasterboard brings with it a load more questions (such as if you fitted it in a kitchen, how on earth do you attach heavy units to it?!).

I've heard that a beginner should really stick to 11'' trowels, but the pre-worn marshalltown trowels don't go that small. Tyzack do an 11'' finish trowel for around £30, but doesn't say anything about it being pre-worn. Do you have to wear one in? There's not much said about this side of things on the net! Would 13'' be okay for a beginner

Packing out the grounds? What should I use? I assume whatever I do use will have to be narrower than the grounds as otherwise I wouldn't be able to remove it after the plaster has set?

I'll stick to Bonding then. There's no point using browning if you've already tried and not had much luck with it!

Thanks for the continued advice.

The bunch of 50's are on their way to you, DJ. I don't know what's wrong with your Judiths, but perhaps you could buy some new ones with it!! And thanks too, Ultimate Handyman.

packing ot grounds you would jut use a wedge of timber or plastic, even cardboard if you only need to pack a mil or so.

trowels....
now as a second best i would recommend tyzak. i'm not really sure what size you should go for as i only started with an 11 in so i don't know if it would be easier to start with a 13 or 14, maybe a beginner could advise!!

if you look below at the right hand trowel you will see all the edges are rounded off, that is worn in just nice for skimming.
the left hand one isn't worn in so would leave loads of trowel marks, on the occasion i needed to get a trowel to a worn in stage very quickly i have used an oilstone to get those edges nice.

as for judiths, i don't want any more, it is cockernee rhyming slang and an ongoing joke at TT.......

judiths=judith chalmers, rhymes with farmers. farmers is slang for farmer giles, which is rhyming with piles. piles are haemorrhoids. hence, judiths are haemorrhoids and if you have a nasty case of em you certainly don't want any more no matter how many 50's you offer

Ah yes, judiths. Very nice!

Well, I think I've got enough answers now! Just got to get all the equipment together and pluck up the courage and I'm ready. When I do, I'll take a picture for you all!

Cheers.