repairing lath + plaster ceiling

Hi
Ive got two questions really.
Firstly, we have a small (2.5' by 2.5') ceiling at approximately 45deg over the stairs between the horizontal downstairs ceiling and the vertical wall of the stairwell. The plaster on this bit of ceiling was completely shot falling off. Underneath are the wooden slats attached to three joists.
Since Im not too bad at plastering now (did a course near Bedford and plenty of practice) I tried to replaster this with the normal sand/cement mix undercoat. Of course I had great difficulty in getting much of this to stay in place.
My question is therefore, is it reasonable to cover this ceiling with plasterboard ? If so, can I leave the wooden laths in place and just screw the plasterboard into the joists through the laths or should I also remove the laths which will obviousyl create more mess.
I can then use some plaster or filler or something to fill the curves between the old plaster and the new plasterboard.
Secondly, the same downstairs ceiling is coming away from the laths in places although the plaster is still in one piece. The ceiling has been wallpapered which is holding most of it in place I think.
Is there anything I can do to secure the plaster to hte laths again ? Is an alternative to fix plasterboard over the whole ceiling ? Again I dont really want to resort to taking teh whole ceiling down. What is the correct way to do this ?
Thanks
Tim
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I've replastered lathe ceilings using normal undercoat plaster and it seems to stick fine, I tended to squidge it on so that some was forced between the lathes, which I'd guess helped it stay in place, try using undercoat plaster instead of the sand and cement.
--
bof at bof dot me dot uk

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Bof,
Thanks for the rapid reply !
I guess Im tempted by the plasterboard option because it liklely to be a quicker and less messy (certainly with plastering).
Would this method work or is it a bodge job ? I want to do this properly.
Tim
writes

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Tim Smith wrote:
<snip>
You did check the FAQ for this newsgroup before posting, didn't you... http://www.diyfaq.org.uk/miscellaneous.html#Repairing :-)
David
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Oops.
Sorry - I have to admit I didnt....
Thanks for the pointer though - plasterboard it is !
Tim

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snipped-for-privacy@timdsmith.co.uk says...

You should have used bonding coat, not cement. It's really not too hard to plaster wooden lath ceilings - I just scrape on a layer of bonding to fill the gaps, then level it off with another coat straight away. If you need to build up a thick undercoat it might be better to apply a thinner layer and let it firm up before adding another layer - I've had sags that I had to scrape back before I could apply the topcoat, but that might have just been an overly wet mix.
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On Fri, 25 Mar 2005 17:44:57 -0000, "Tim Smith"

The _correct_ way to do it is the way it was done before, but that requires a new head cos the words bonding and plasterboard go out the window to be replaced by lime mortar and goat hair
The materials might be trickier to locate (where are you?) but if you can do modern plastering then the technique is easy enough and lime mortar sets slowly so you don't need to feel rushed. If you want to go that route then I'll explain in more detail
Even if you use modern materials I would add some short strands of fibre to give tensile strength; hair, fibreglass, string, straw or whatever
Anna
~~ Anna Kettle, Suffolk, England |""""| ~ Lime plaster repairs / ^^ \ // Freehand modelling in lime: overmantels, pargeting etc |____| www.kettlenet.co.uk 01359 230642
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Anna is so right. Abandon the gypsum and use the real stuff. Here's a couple of firms that will supply goat hair, lime putty and everything else you need to fix a lath and plaster ceiling the proper way. Order on line from Womersleys or Mike Wye:
http://www.womersleys.co.uk/acatalog/renders_plasters.html http://www.mikewye.co.uk /
Get more advice from Perdiod Property UK Forum. Lots of experts willing to share their knowledge about looking after old houses properly hang out there.
http://www.periodproperty.co.uk/index.shtml
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