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  1. #1
    Join Date
    Dec 2005
    Location
    Perth, W.A
    Posts
    125

    Default Plastering-Did I stuff up?

    I removed benches near a kitchen sink and rendered it smooth then applied a gyprock top coat over that. I shouldn’t have bothered really because a cupboard will hide the area but I have become heavily addicted to topcoat and cant help myself. No, Really!

    I read a post that said any damp would cause topcoat to revert to it's original state.

    Question is would there be any moisture in this area or enough that it would affect the plaster?

    Can I apply a coat of something to protect the wall?

    Also...Perhaps someone can give me a tip on how to get good plastered corners. I have read the plaster site but it talks about gyprock sheets and corners. I get them looking reasonable then touch it that ONE time too many and have to start again.

  2. #2
    Join Date
    Feb 2008
    Location
    Aust
    Posts
    192

    Default

    but I have become heavily addicted to topcoat and cant help myself
    I strongly advise not to snort topcoat

    Can I apply a coat of something to protect the wall?
    Paint.
    Don't set a wall anywhere where there is constant moisture. Thats what tiles are for.

    Have a look at fixing corner beads prior the top coats
    c2=a2+b2;
    When buildings made with lime are subjected to small movements thay are more likely to develop many fine cracks than the individual large cracks which occur in stiffer cement-bound buildings. Water penetration can dissolve the 'free' lime and transport it. As the water evaporates, this lime is deposited and begins to heal the cracks. This process is called autogenous healing.

  3. #3
    Join Date
    Jul 2006
    Location
    Melbourne
    Posts
    675

    Default

    check out these videod http://www.youtube.com/profile_videos?user=Tennex01&p=r

    The biggest concern with top coat getting wet is when tiles are layed over it.

    If moisture gets under the tile it will cause the tile to let go. If you have topcoated and area to be tiled I suggest you tank the area with a suitable water proof membrane.


    Cheers
    Great plastering tips at
    www.how2plaster.com

  4. #4
    Join Date
    Feb 2008
    Location
    Aust
    Posts
    192

    Default

    If moisture gets under the tile it will cause the tile to let go. If you have topcoated and area to be tiled I suggest you tank the area with a suitable water proof membrane.
    or scrape it back rod?

    If setting float (cement render) would you base coat prior Rod?
    c2=a2+b2;
    When buildings made with lime are subjected to small movements thay are more likely to develop many fine cracks than the individual large cracks which occur in stiffer cement-bound buildings. Water penetration can dissolve the 'free' lime and transport it. As the water evaporates, this lime is deposited and begins to heal the cracks. This process is called autogenous healing.

  5. #5
    Join Date
    Jul 2006
    Location
    Melbourne
    Posts
    675

    Default

    I'm not a renderer by any means. But when I have to float any render or other large areas I use cornice adhesive. Simply because you can manipulate the setting times much easier than base coat and it is designed to be re-workable by wetting it down as it sets allowing you to pollish the work with slurry. Much the same as hard plaster but much more user friendly.

    Now if I was a renderer I would use the real thing "hard plaster" but it is a plaster that I am not as familiar with as I am with cornice adhesive.

    If you are going to tile the area I would either sand or scrape back the top coat. You dont need to have a perfect finish under the tiles. Even deep scratching of the surface where you are tiling will work well. The flat base for tiling remains but the glue will have a better surface to adhere to.

    Cheers Rod
    Great plastering tips at
    www.how2plaster.com

  6. #6
    Join Date
    Dec 2006
    Location
    perth
    Posts
    59

    Default

    Chromis did not mention anything about laying tiles over the top coated area. But yes if you have to do tiling where you top coated, it is best to scrape off to bare render. The top coat will be easy to remove. You can tile over a strong set.(recommended 50%- %50 lime putty to plaster) And I think what Rod mentioned about cornice cement if you waterproof after that, it should hold and be strong enough for standard tiles.

    There are external angle beads you can put onto the brickwork before float (render correct term mortar)

  7. #7
    Join Date
    Feb 2008
    Location
    Aust
    Posts
    192

    Default

    Generally an old plasterers or tilers notch trowel will scrape back standard setting plaster so topcoat wouldn't be far off it.
    Try not to damage the float too much as the tiles wont sit flat if heavy damage is the result of going crazy on the set.

    Interesting about the cornice cement.

    Whats the best way to retard cornice cement if your doing say 6 m2?

    I find cornice cement does set rather fast?
    c2=a2+b2;
    When buildings made with lime are subjected to small movements thay are more likely to develop many fine cracks than the individual large cracks which occur in stiffer cement-bound buildings. Water penetration can dissolve the 'free' lime and transport it. As the water evaporates, this lime is deposited and begins to heal the cracks. This process is called autogenous healing.

  8. #8
    Join Date
    Jul 2006
    Location
    Melbourne
    Posts
    675

    Default

    Citric Acid or lemon juice is the best.
    Great plastering tips at
    www.how2plaster.com

  9. #9
    Join Date
    Dec 2006
    Location
    perth
    Posts
    59

    Default

    You can retard when you got nothing else with urine. Not too much though.

    Years ago we were doing some setting in units 4 plasterers and the plaster was going off like crazy sometimes before we could finish the drum. We were putting cream or tartar in the mix but still it was going off fast and having to work flat out trying to finish off. Well I got sick of it I got a little urine and put it in the mix and it was smooth sailing. The other worker came in from the other room saw us cruizing and said what did you do? in it? I said yes.
    But if I were to do 6m2 I would use plaster You got skills and a mixing drill with paddle get yourself a weed sprayer to add fine mist spray when the walls are starting to harden. Im not sure you use putty lime in eastern states as I worked in Melbourne many years ago and the lime came in bag form.

  10. #10
    Join Date
    Dec 2005
    Location
    Perth, W.A
    Posts
    125

    Default

    WOW that topic went off track quite a bit
    No I'm not going to put tiles over the top coat. There's going to be a small stainless steel splash back moulded into the bench top, under a window.

    I doubt there will be any moisture but I just wanted to be safe and apply a protecting coat just in case.

    Also I watched the videos (or some) but I think I need tips on external angles not internal...

  11. #11
    Join Date
    Jul 2006
    Location
    Melbourne
    Posts
    675

    Default

    Great plastering tips at
    www.how2plaster.com

  12. #12
    Join Date
    Feb 2008
    Location
    Aust
    Posts
    192

    Default

    Thanks for the tips fellas. Im not sure about the urine though

    What about potassium hydrogen tartrate? (cream of tartar)

    Does that work?

    Thanks in advance..
    c2=a2+b2;
    When buildings made with lime are subjected to small movements thay are more likely to develop many fine cracks than the individual large cracks which occur in stiffer cement-bound buildings. Water penetration can dissolve the 'free' lime and transport it. As the water evaporates, this lime is deposited and begins to heal the cracks. This process is called autogenous healing.

  13. #13
    Join Date
    Dec 2006
    Location
    perth
    Posts
    59

    Default

    There are external angle beads you can put onto the brickwork before float (render correct term mortar) brand name ro1 and ro2
    I used to call them r2 d2 in the early days like star wars rondo lock they are rendering beads for mortar. The other types are p32 for gyprock work. As Rod will have some on his site. The p32 you can put over the render before set using cornice cement.
    Placing the render beads onto bare brickwork, you can either use concrete nails or 20-25mm clouts depending how hard brick mortar joints are. Use a straight edge to make level. I have been pre drilling 5mm holes in brick joints or bricks and using 38mm nylon anchors. This way if the beads need adjusting. you can hit the nail sideways. The trick is dont knock the nails all the way in until you are sure the bead is set correct. Then you can knock nails in all the way. Another trick if the brick mortar joints are hard pre drill a little with a 3mm masonary drill bit the hammer in nails. Trouble is sometimes the nail just bounces.
    Cream of tartar does work but I think citric acid or lemon juice will be better. The urine does work its acid. I like the terminology autogenous healing.

  14. #14
    Join Date
    Dec 2005
    Location
    Perth, W.A
    Posts
    125

    Default

    I have patched up a wall that extends to the corners and I didnt need to render the whole lot. The corners have plaster on already.

    I guess in that case I just use a straight edge to neaten the corners.

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