Can you skim over newly overboarded ceiling already skimmed twice

The nuance here is ... was the over boarding done as flat and precise as possible .... was it done direct with the old ceiling ......or as I would recommend, cross batten ceiling first with 3x1 to ensure 'flatness' and ease of re boarding. Many existing ceilings are bowed and mishapen and therefore sometimes on reboarding direct, the boards inevitably may mirror the bad shape making plasterboard joints a challenge too lose in the skim process. Without flatness its a never-ending battle as skim is literally that a thin 2 coat system. having said that...when we have encountered the problem you have now we have first coated it with a multi finish and bonding plaster mix to create a thicker coat to 'flatten' irregularities first.... then finished with a skim coat....HOWEVER .... now its had a number of layers (2 x 2layer skim) one may wish to question how thoroughly were the initial boards fixed to the original ceiling. If cross battening was carried out and the PB was screwed every 250 mm or so then you should be ok.... If nailed as I have seen in the past , then not so good. The fixing integrity can slowly fail and cracks may start to appear.... you need to first, establish the original over boarding process if at all possible.

OK, so rule of 3.strikes comes in. It's over boarded, so reason, it's skimmed, then skimmed, so it's a straight know, their is issues, rip it down, bit of brawn, few sheets, then put noggins in spaced at. The 120 so boards are secure on all four. Sides, stagger the boards like brick, have centre noggin for light, scrim joints, patch the wall edge first as then u got clean edge to skim to. Pva all the time inst the way, brawn and pride most jobs need

OVERBOARD normally mimics the surface you are covering with, unless you lay the battens level prior to boarding (as mentioned from others). The thinner the board the flexier it is thus, more noticeable will be the unevenness. TROWEL LINES indicate How uneven the ceiling is, or How much experience the plasterer has (no offence) RE-SKIM Yes you can, but the boards have to be fixed with screws at least every 300mm, as long as the surface has been pva'd twice (1-5 and 1-3 my choices). You can always put some screws on, providing you know where the joists are. 12.5mm original ceiling (or more if lath and plaster) 4mm old plaster 12.5mm new boards 3-4mm new plaster 25mm at least screwed to joist so,= 60-70mm long screws (be careful of wires etc..) CRACKS ON WALL ____Solid Wall___ If it is one or two big cracks and the plaster sounds hollow, then dig/scrape off and bond (plus metal lath optional) and skim. If there are too many fine cracks, then a quick scrim and skim should solve the problem. ____Stud Wall___ If you see cracks there, see if the boards need reinforcing with screws first before applying scrim tape and skim (the plasterer). ___Plastered Twice?__ Apply Thistle Bond It pva and then skim or, Blue Grit pva (cheaper) and then skim. ........................... It is ok if you don't know how the plasterer (or other tradesman) dixed the boards. 1. Aske him/her/them 2. (My bet) If you are planning to plaster anyway, cut some holes with a holesaw to find the joists and just reinforce with screws. You can also put back the cutouts woth a batten behind. 3. Invest in a stud detector (you can always take it back if it doesn't work). Multifinish is hars to sand down unless you get someone who does airless spray plaster ( but they have to be good) as that kind of plaster is more like stucco and it is easy to sand in 5 hrs or next day (depending on product) and the applicator will sand the surface himself (herself). As per the curved wall 1. If the curve goes left to right, it is best to skim whole wall (or affected area) and feather in if needed. 2. If the curve goes floor to ceiling then, yes one can feather it in upwards ( or downwards). 3. If the curve is not rigjt, one would need to make it right by bonding or float and set, even if they have to make a template (hard stencil type, on runners). Good luck.

Yes it is possible as long as you put a good coating of pva first maybe even two coats.