Help with late Victorian walls/plaster

Discussion in 'Builders' Talk' started by squarepegs, Apr 19, 2018.

  1. squarepegs

    squarepegs New Member

    Hi, we're in the process of moving in and in my enthusiasm to 'get to know' the old house went straight for the 4-5 layers of wallpaper and paint. Now that it's all off I can better see what I'm dealing with. Please forgive my lack of knowledge on terminology as I'm not familiar with all the names for the layers I'm looking at and would very much appreciate if someone could clarify what everything is so I know what refers to what.

    Starting with the ceiling. I know it's wooden laths attached to the joists. They are covered in a half inch thick layer of greyish blue undercoat, topped off with a thin layer of plaster of some kind.

    The walls have the same setup, brick then the same gray grittu undercoat and finally a thin layer of plaster.

    Obviously the plaster has blow off in large patches, but at least 70% of it is still on the walls and ceiling quite solidly.

    I'd like to know what the best approach would be to dealing with it. I intend to do the work my self.

    Ideally I would like to patch the large areas that are missing the old plaster, prep the whole surface, skim with fresh layer and paint.

    I know that I should tape the cracks up, but am in doubt as to what:

    A. Material to use to patch the missing areas
    B. Material to use as prep layer prior to patching those areas
    C. Material and process for prepping the rerendered surface for a new skim layer.

    Hope this all makes sense and thank you for any advice.

    I do not wish to board up the ceiling or the walls. I want a fresh layer to paint over, for both walls and ceiling.

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  2. Longy75

    Longy75 Member

    Not wanting to sound disreptful but if you've not plastered before I think you may struggle to get a good finish on what you've got there and it may pay to get someone in. Having said that I'll try and help point you in the right direction.

    A) if all internal walls then you can use thistle bonding to fill the large areas of blown plaster ruled off to the wall, originally it would have been a sand and cement render and would def use that for external walls.
    B) walls can be wetted down with water prior to floating
    C) you can use pva however I'd use blue grit applied 24 hours before because those walls will suck like a .........
    You said about taping the cracks if there are lots and are that bad you can get mesh on a roll (looks like scrim tape but wider and longer) and bed that into your first coat of skim
    As for the ceiling I know you don't want to but I would definitely overboard if it's blown, plus you'll prob find it's got distemper and it's not nice seeing your hard work on the floor when it doesn't take.
     
    Jord86 likes this.
  3. squarepegs

    squarepegs New Member


    Thank you very much for the input. There is one exterior wall in the room.

    I've not decided yet whether I'll have someone in, a friend who is a plasterer suggested fireboarding ceiling and putting insulated board on external wall, both things I wanted to avoid if possible for the sake of not drilling a bunch of holes in the ceiling to locate joist or lose 5cm of internal space. It's a fairly original house and I was hoping to keep it that way.

    I don't think there is any distemper on the ceiling but it looks like it on the higher parts of the walls at least. I dot mind washing it off and prepping it.

    I saw a suggestion somewhere for patching the plaster gaps with thistle hardwall and render up to level then PVA then skim. Would this be correct? Can same be done for ceiling?

    If it need to be boarded, then so be it, but trying to make sure I've covered all options.

    So what I'm looking at is a layer of sand and cement undercoat with a layer of lime plaster? Is that right.?
     
  4. KIAB

    KIAB Super Member

    Best option for ceilling is rip the lot down & reboard & skim.

    Old plaster lath ceiling in that condition are not worth saving,you could patch it today & half the ceiling could come down,days weeks,months later & the mess & dust is bad.

    A filthy job to do, but the end result will be worth it.:)
     
    DIY womble, BMC2000 and Astramax like this.
  5. squarepegs

    squarepegs New Member

    When you say that, including the undercoat leaving only the lath exposed?

    Why not just boat over it all (which was suggested by plasterer)
     
  6. KIAB

    KIAB Super Member

    You can't be 100% sure what your fixing into when overboarding,plus you following the contours of the old ceiling so plaster might up thicker in places to achieve a level ceiling when skimming.

    Also if you going to rewire, then it makes the job easier with access.:)
     
  7. Longy75

    Longy75 Member

    Thistle hardwall is for high suction backgrounds, and I assume under the plaster it is standard brick? So bonding would be fine although either will work. As mentioned in my previous post you can pva, however the walls will be so dry after all this time I think you'll struggle to kill the suction fully so you might have parts of your walls drying whilst some parts are still wet.
    In theory you can use bonding on the ceiling, but my concern would be the extra weight you will be applying to an already blown ceiling, not nice if it pulls the ceiling down. If the ceiling is reasonably flat you can use 12.5mm boards as that will help to level it out and screw into existing joists, not the lathes, sounds daft but I've seen it done :rolleyes:.
    How is the house constructed ie do you have cavity walls? If not is it rendered? As that will determine what can be used on exterior walls.
     
    KIAB likes this.
  8. KIAB

    KIAB Super Member

    I've done that, & screwed to joists/trimmers that are floating .:rolleyes:

    And I've had plaster lath ceilings come down, sometimes several weeks/month later after patching, & one, my patched section stay up & ceiling other end of room came down.:oops:

    So, I prefered to have the lot down & reboard from scratch.:)
     
  9. Astramax

    Astramax Super Member

    Arrrggghhh the results of the good old wallpaper steamer :confused:
     
  10. Mr Rusty

    Mr Rusty Screwfix Select

    I've just done this in a whole house. I bet the wall plaster is hollow and loose in many places when tapped. If you intend to stay there the only real solution is to rip it all off including the laths and start again. You can either have the walls fully plastered or dry line with plaster board using insulated on external walls. This is well worth doing. You can overboard ceilings and if you want to retain decorative cornices it's the only way. But otherwise rip it down. Horrible dirty job but the best in the end.
     
    BMC2000 and KIAB like this.
  11. Mr Rusty

    Mr Rusty Screwfix Select

    I should add if it isn't hollow sounding and the original plaster sounds solid just get it reskimmed.
     
  12. Bob Rathbone

    Bob Rathbone Screwfix Select

    Overboard it all as you suggest. It makes an awful mess ripping down a ceiling, then you find the beams aren't level.
     
  13. Jord86

    Jord86 Screwfix Select


    If you're living there for ten years plus, rip it all out and start from a blank canvas. Seriously. I and some of the others who've advised you on this thread already will tell you it's a false economy to board over and hide things, especially if you're rewiring or plumbing areas that could do with access and renewing.
     
    Mr Rusty and KIAB like this.
  14. DIY womble

    DIY womble Well-Known Member

    If if you want extra soundproofing and not worried about the height you could leave the the plaster on the Ceiling to save the mess .baton across the joists ,levelling out ,patch as previously described ( don't press too hard as to weaken the existing ) infill with rockwool between new batons , new boards then get someone to skim
     
  15. Jimmycloutnail

    Jimmycloutnail Screwfix Select

    What’s the point of adding 25mm of rockwool? Absolutely pointless, double boarding with sound board yes, but wouldn’t want to fix that to Battens fix through lathe ceiling
     
  16. DIY womble

    DIY womble Well-Known Member

    Save the mess , the dust gets everywhere, was just giving another option , not saying it was appropriate
     
  17. Jimmycloutnail

    Jimmycloutnail Screwfix Select

    It is a messy job but sometimes you just gotta rip it down, have it down in a hour ( then 3 days to de nail and clean up)
     
  18. DIY womble

    DIY womble Well-Known Member

    I agree , its the direct approach, as I said, just giving options for diy , although on occasions I have used this procedure
     
  19. DIY womble

    DIY womble Well-Known Member

    Soundproofing is best achieved by a combination of layers of different materials also baton across for better results
     
  20. Jimmycloutnail

    Jimmycloutnail Screwfix Select

    Yeah I agree but full fill with acoustic batts between joists not 25mm between Battens, with an acoustic floor above and separated sound board ceiling below
     
    Jord86 likes this.

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