Rendering over part painted internal wall

[sucramuk]

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

[roughcaster]

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.

[sucramuk]

Thanks RC,

As I've stated I'm in South Africa and although they have gyproc they don't seem to have a bonding plaster?
This link shows the products available, http://www.gyproc.co.za/siteimgs/C%20Plast-screen.pdf.

Will sand and cement be ok?

Thanks again

[sucramuk]

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

[roughcaster]

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.

[sucramuk]

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.

[roughcaster]

When you say slurry on,,, what is your slurry made of?

Roughcaster.

[sucramuk]

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."

roughcaster wrote:

When you say slurry on,,, what is your slurry made of? Roughcaster.

[roughcaster]

I've just read your post properly Sucramuk,, and noted what the slurry was made from.

Roughcaster.

[joe-90]

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).

[roughcaster]

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.

[sucramuk]

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.

joe-90 wrote:

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).

[joe-90]

SDS drill and a flat chisel would do it.

[sucramuk]

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

joe-90 wrote:

SDS drill and a flat chisel would do it.

[roughcaster]

Enjoying life out there?? All that sun. We've had non stop rain here for the last 24hrs.

Roughcaster.