Rendering over part painted internal wall

Discussion in 'Plastering and Rendering' started by sucramuk, 2 Sep 2009.

  1. sucramuk

    Joined:
    15 Oct 2004
    Messages:
    19
    Thanks Received:
    0
    Country:
    United Kingdom
    Hi,

    Situation is that after removing bathroom tiles I'm left with 1/2 half of wall has tile adhesive (mostly dot/dabbed, not spread) onto render other half painted.
    The top half (painted) tiles came away cleanly, bottom half (render) impossible to chip off tile adhesive (takes render off wall).
    Dont want to tile top to bottom with tiles (cost being a big issue).
    The render half is sticking proud by up to 12mm in places.

    My idea is to (after searching this forum) apply slurry to painted area and render wall level/skim.

    My questions/thoughts

    1. Will removing flaking paint, scour with wire brush and sparrow pick the walls provide sufficient key. (really cant use the angle grinder)

    2. As stated the render half is up to 12mm proud in places, should I render painted 1/2 level with render first and then when dry render over whole wall?

    3. Slurry mix, apply to whole wall or just painted? What mix and what sand? Should I let dry first before applying renderAlso in South Africa so can only use permobond which I believe is a PVA.

    I did find this post, http://www.diynot.com/forums/viewtopic.php?t=181887, but it seemed to refer to skimming

    Thanks for any help
     
  2. roughcaster

    Joined:
    2 Aug 2007
    Messages:
    4,446
    Thanks Received:
    545
    Location:
    Moray
    Country:
    United Kingdom
    Rather than use cement render,,,, you could,, after preping the wall, removing loose/flaking paint etc,,,, slurry the walls (top and bottom) as shown in the pics, and then use bonding coat plaster to level off the step in the wall,,,, let that deeper area set, and then go over the whole wall with the bonding coat,, finishing it off with multi finish plaster, it would give you a smooth finished wall.

    Roughcaster.
     
    • Thanks Thanks x 1
  3. sucramuk

    Joined:
    15 Oct 2004
    Messages:
    19
    Thanks Received:
    0
    Country:
    United Kingdom
  4. sucramuk

    Joined:
    15 Oct 2004
    Messages:
    19
    Thanks Received:
    0
    Country:
    United Kingdom
    Slurry on, looks just like the picture in the other post, makes the bathroom very dark!

    Do I need to PVA again prior to applying the render?

    Thanks
     
  5. roughcaster

    Joined:
    2 Aug 2007
    Messages:
    4,446
    Thanks Received:
    545
    Location:
    Moray
    Country:
    United Kingdom
    Your link didn't work Sucramuk. Hardwall would be ok to use if you couldn't get Bonding, but again, is that availabe where you are? You could use sand and cement, say 4 to 1, but you would really need to roughen up the painted surface , to provide a good mechanical key, and also use a good quality PVA. As cost is an issue, this would be about the cheapest way to do it,, but time consuming.

    Roughcaster.
     
  6. sucramuk

    Joined:
    15 Oct 2004
    Messages:
    19
    Thanks Received:
    0
    Country:
    United Kingdom
    I did spend a lot of time removing flaking paint, sparrow picking the walls, gouging criss cross lines with heavy duty blade etc, used a branded pva 'permobond' which seems to be the brand leader here.

    Just to recap, I have applied a cement/sharp/pva slurry to walls, I can now apply (when dry) a render coat of sand/cement to it. You've stated 4 to 1, would I need to apply further PVA onto the dried slurry prior to rendering?


    The plaster's available are (taken from the gyproc.za website pdf):

    RhinoLite Blue 4 All
    A multi-purpose finishing plaster, applied between 5
    and 75mm thick (two or more applications may be
    necessary). This versatile plaster can be applied onto
    a wide range of substrates. These include: brick and
    block, sand and cement and RhinoBoard (refer to
    manufacturer’s application specifications).
    Apply RhinoLite Blue 4 All in a one-coat application
    method, by using a rubber float to close in the surface.
    For interior use only.

    RhinoLite Yellow 4 CreteStone
    A thick skim finishing plaster applied at thicknesses
    of more than 2mm and less than 6mm thick. This
    skim plaster can be applied onto RhinoBoard or sand
    and cement surfaces (refer to manufacturer’s application
    specifications).
    Apply RhinoLite Yellow 4 CreteStone in a skim application
    method.
    Always ensure perfectly flat surfaces for application
    of any skim finishing plaster.
    For interior use only.

    RhinoLite Red 4 Board
    For superior internal finishes, this skim finishing plaster
    is applied at thicknesses of more than 2mm and
    less than 5mm thick. This skim plaster can be applied
    onto RhinoBoard only (refer to manufacturer’s application
    specifications).
    Apply RhinoLite Red 4 Board in a skim application
    method.
    Always ensure perfectly flat surfaces for application
    of any skim finishing plaster.
    For interior use only.

    RhinoLite Natural Plus
    A multi-purpose natural gypsum finishing plaster,
    applied between 5 and 75mm thick (two or more
    applications may be necessary). This versatile plaster
    can be applied onto a wide range of substrates.
    These include: brick and block, sand and cement and
    RhinoBoard (refer to manufacturer’s application
    specifications).
    Apply RhinoLite Natural Plus in a one-coat application
    method, by using a rubber float to close in the
    surface.
    For interior use only.
     
  7. roughcaster

    Joined:
    2 Aug 2007
    Messages:
    4,446
    Thanks Received:
    545
    Location:
    Moray
    Country:
    United Kingdom
    When you say slurry on,,, what is your slurry made of?

    Roughcaster.
     
  8. sucramuk

    Joined:
    15 Oct 2004
    Messages:
    19
    Thanks Received:
    0
    Country:
    United Kingdom
    1 part cement, 1 part sharp sand, 50/50 mix of PVA water.
    Based on info from the permobond website.

    "Scratch coats and spatterdash treatments. Mix 1 part cement with 1 - 2 parts clean sharp sand. This should be gauged with a 50:50 mix of Permobond and clean water to give the required consistency for brush or trowel application."

     
  9. roughcaster

    Joined:
    2 Aug 2007
    Messages:
    4,446
    Thanks Received:
    545
    Location:
    Moray
    Country:
    United Kingdom
    I've just read your post properly Sucramuk,, and noted what the slurry was made from. :oops:

    Roughcaster.
     
  10. joe-90

    Joined:
    28 Oct 2005
    Messages:
    30,161
    Thanks Received:
    928
    Country:
    United Kingdom
    You are better off hacking off the old adhesive and then patching up the divots. Far less trouble than attempting to level the wall. (not easy for a beginner).
     
    • Thanks Thanks x 1
  11. roughcaster

    Joined:
    2 Aug 2007
    Messages:
    4,446
    Thanks Received:
    545
    Location:
    Moray
    Country:
    United Kingdom
    If your wall has a good key,, plus the slurry you have put on is rough to the touch, that'll hold your render no problem. It wont do any harm putting on a coat of pva just before you start. Let it go tacky, then put on about half the required thickness, (6mm) scratch it lightly, then let it set, next day, bring out to your 12mm,, float/sponge it off, let it set,, then you're ready to skim it over with a finishing skim. Agree with Joe's comments too.

    Roughcaster.
     
    • Thanks Thanks x 1
  12. sucramuk

    Joined:
    15 Oct 2004
    Messages:
    19
    Thanks Received:
    0
    Country:
    United Kingdom
    I'm not a total plastering beginner and am a carpenter by trade so would hope to think I have a bit more practical skill compared to a weekend diyer . Have already levelled up some walls (not painted) in the kitchen without issues.

    But to try and hack the wall clean would be a nightmare, I've got no idea what they use here but its 'ard!. Only moved over here in June of this year.

     
  13. joe-90

    Joined:
    28 Oct 2005
    Messages:
    30,161
    Thanks Received:
    928
    Country:
    United Kingdom
    SDS drill and a flat chisel would do it.
     
  14. sucramuk

    Joined:
    15 Oct 2004
    Messages:
    19
    Thanks Received:
    0
    Country:
    United Kingdom
    It would, but the 'bricks' the render/adehive is on is 2.5" clay honeycomb type blocks of which the brick collapses as opposed to the render coming away due to render being harder than the block.
    Thanks for the suggestion though

     
  15. roughcaster

    Joined:
    2 Aug 2007
    Messages:
    4,446
    Thanks Received:
    545
    Location:
    Moray
    Country:
    United Kingdom
    Enjoying life out there?? All that sun. ;) We've had non stop rain here for the last 24hrs. :rolleyes:

    Roughcaster.
     

Share This Page