# Forum Home Renovation Tiling  Prepping existing brick, cement render, white set plaster for tiling

## DaleBlack

Hi 
I am re tiling or getting a bathroom re tiled, looks as below at present   
there is still a combination of tile glue, white set plaster everwhere. Note I will probably do floor to ceiling tiles so unlike the images above where tiles only existed in the shower area, theyll now be everwhere. 
according to this  http://cdn.ardexaustralia.com/pdf/sp...Substrates.pdf   

> All  contaminants  such  as  paint,  white  set  gypsum  based  plasters,  waxy/oily    residues  and  laitance  shall  be  removed,  and  smooth  steel  float  finished   concrete   scarified,   by   mechanical   means   (e.g.   by   grinding,   needle   gun    scabbling  or  abrasive  blasting)  to  achieve  a  fine  textured  open  pored  surface   suitable for the tile adhesives.    Note: render that is very weak and able to be rubbed away easily is not suitable  for the adhesive fixing of tiles. It must be removed and replaced.

  rather then just chip away bits of the white set back 
as per this style   
, i should take the effort to strip it all back. I started to do this with a SDS Rotary Hammer but it was too powerful, maybe just my technique, and i went back to brickwork if you see one of the images above. The render doesnt appear drummy so to chip away everything back to brickwork appears a waste of time and money. 
So what is the best technique and tool to just strip back the thin layer of whiteset to the grey cement render   Needle Gun scrabbling (couldnt find any good videos of this)Grinding wheel on a angle grinder?https://www.kennards.com.au/concrete-renovator1.htmlwire brush on a standard cordless drill  
surely something other then a scraper by hand

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## cyclic

3

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## DaleBlack

> 3

  Cyclic so you use this tool/method? 
I went past 2 different tile shops both of whom had guys who also tile on the side and they thought the idea of removing absolutely all the whiteset is excessive and something only the chemists would say being purists. 
They seemed to say that chipping away about 50% exposes enough render such that adhesion beyond 32kg/m2 (or some such metric) is achieved. One that sold RLA group Primer (green coloured)  http://rlagroup.com.au/product_img/p...ALPRIMERV3.pdf 
said to dilute that product 50% so it soaks through the white set (the white set not chipped) to the underlying render. He said he followed this method on a bathroom with floor to cornice tiles, 300*600, 11 years ago with no issues?

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## cyclic

> Cyclic so you use this tool/method? 
> ?

  Last time I did a bathroom like that, yes, I used a very similar machine to tidy up the walls.
And I did not remove all the white set, just did a tidy up.

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## DaleBlack

> Last time I did a bathroom like that, yes, I used a very similar machine to tidy up the walls.
> And I did not remove all the white set, just did a tidy up.

  cheers, did you find the white set comes off after only one pass or did it require several?

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## cyclic

I think the machine I used back then was a hilti with slightly different disc, but it tore it off quite easily to the point of having to be careful not to gouge it too much.

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## rebuildr86

i do this for a living, and after having to redo some of my work and experinecng how frighteningly easy it was to remove some of my tiles, i now remove all plaster when doin floor to ceilings, and i do so with one of these: https://www.amazon.com/Champion-Chis.../dp/B01N7JZDV4 
The blade is flexible so it bounces off the render rather than chisseling into it. perfect on a small ozito 120 dollar jackhammer.
Now, since buying that, i can strip a bathroom of plaster in about half an hour back to a perfectly falt smooth render with minimal reparis required. 
regarding the RLA product idea, absolutely not. TO begin, paint weighs about nothing, and to paint white set, you MUST use an oil based sealer binder, which binds the whiteset together. Water is thicker than the refined oil used as the carrier (penetrater) in this and cannto penetrate andbind it all together. Add to that the weight of tiles and u are likely to have a sad outcome. 
There is no substitute for at least removing large 50% portions of the plaster when hanging wall tiles. These idiots u see who scour lines into the whiteset are a joke and may as well not even bother. 
Sayign all that, i do make an absolute F**ing mess removing the plaster, so anythign that can do it with a dust extractor sounds bloody great.

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## DaleBlack

> i do this for a living, and after having to redo some of my work and experinecng how frighteningly easy it was to remove some of my tiles, i now remove all plaster when doin floor to ceilings, and i do so with one of these: https://www.amazon.com/Champion-Chis.../dp/B01N7JZDV4 
> The blade is flexible so it bounces off the render rather than chisseling into it. perfect on a small ozito 120 dollar jackhammer.
> Now, since buying that, i can strip a bathroom of plaster in about half an hour back to a perfectly falt smooth render with minimal reparis required. 
> regarding the RLA product idea, absolutely not. TO begin, paint weighs about nothing, and to paint white set, you MUST use an oil based sealer binder, which binds the whiteset together. Water is thicker than the refined oil used as the carrier (penetrater) in this and cannto penetrate andbind it all together. Add to that the weight of tiles and u are likely to have a sad outcome. 
> There is no substitute for at least removing large 50% portions of the plaster when hanging wall tiles. These idiots u see who scour lines into the whiteset are a joke and may as well not even bother. 
> Sayign all that, i do make an absolute F**ing mess removing the plaster, so anythign that can do it with a dust extractor sounds bloody great.

   
rebuildr86 thanks for your reply, very helpful with the product link, I do own a Ozito 1500w SDS bit jackhammer. half an hours work is excellent, a guy at a tilers shop was telling me it might be 3 days worth though he was implying a manual scraper. 
Dust wise I am not sure how this flexible blade could avoid dust, its only those grinding cups that seem to be able to have a vacuum added.  
I wonder what is faster, a grinding cup disc setup vs your flexible blade, it seems your blade as 30minutes is not long. 
On the painting issue, I do remember now using a Solver Sealer Binder product to seal the white set in bedrooms prior to painting so it makes sense what you say and your honest enough to say you have had to do your own rework due to not taking enough whiteset off. Do you ever have an issue whereby in the process of whiteset removal the grey cement render is now not level? 
I have taken the render off to the brick in a couple of areas, see images above. How do you patch these? what material?

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## rebuildr86

Yeh if u hold the blade at too sharp an angle it wil blast off the reender. Its not really an issue if its not completely level, but when  its beyond 3mm gouges, then it needs patching so that the membrane is smooth.
To patch render, use a product called dunlop acrylic render, and add a handfull of powder mastic to it while u mix it, this will make it easy to apply and avoid it just falling on the floor off the trowel.

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## DaleBlack

> Yeh if u hold the blade at too sharp an angle it wil blast off the reender. Its not really an issue if its not completely level, but when  its beyond 3mm gouges, then it needs patching so that the membrane is smooth.
> To patch render, use a product called dunlop acrylic render, and add a handfull of powder mastic to it while u mix it, this will make it easy to apply and avoid it just falling on the floor off the trowel.

  Hi so you take this product    http://www.dunlopdiy.com/pdfs/renders_datasheet/Dunlop_Multipurpose_Acrylic_Render_Datasheet_0917.  cmprssd.pdf  MIXING 1. Add approximately 3.0 to 3.5L of clean water to a bucket.2. Gradually add 20kg of DUNLOP MULTIPURPOSE ACRYLICRENDER to the water whilst mixing with an electric mixerto disperse the powder into a creamy, lump freeconsistency. 3. Allow the mix to stand for up to 5 minutes, remix andthen begin applyin 
and add your own addition to their mix such as this     

> A flexible cement-based tile adhesive ideal for large format and  rectified edge tiles and featuring our Dust Less Technology. Suitable  for interior and exterior applications. Commercial and domestic walls  and floors.

   

> Non-vertical slump for easy wall tiling

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## rebuildr86

Yep. And ul use the rest of the powder mastic for the wall tiles  :Smilie:

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## DaleBlack

some feedback on whiteset removal on brick walls to aid new tiles being laid. As in above posts my aim was to remove whiteset but not the render.  *Method 1 - Rotary Hammer (cheap ozito bunnings one) with flexi bit - sds plus* 
After rebuilder86's recommendation     
The end of the blade is square not V shaped like those manual wall scrapers. width 1.25mm. 
Quite easy to use, when you find the right angle, just seems to keep bouncing over the wall removing the whiteset. The image below occurred in seconds and i should post another better image as if i had held it a bit better the whiteset removed is about double again of the below image. So the below doesnt do this tool and method justice, very little dust   
Not sure about your claim to removing all the whiteset in half an hour rebuilder86 but then again I am a amatuer and you do it for a living. *
Method 2 - Diamond bit on griding wheel with dust shroud* 
125mm grinder and a makita brand dust shroud connected to a Ryobi 30L vacuum workshop wet and dry vac     
Results    
certainly takes nearly everything back to the render and pretty quick
at the very start with a freshly cleaned filter in the vacuum, there was no dust or little 
Cons 
My technique was poor meaning in some cases there was gouges like the above that will need to be patched.
This was mainly due to dwelling on spots or going over some old blue waterproofing that wasnt coming off in a single pass, so i leant into these areas on the grinders edge instead of keeping it flat.
The grinding disc seem to glaze on the whiteset so I had a old solid brick in the room and deglazed the disc by pressing it onto the brick every now and then
The Ryobi vacuum was hopeless, it seemed to get clogged fairly quickly and then the dust started coming out. 
I havent made this method seem very good, but when it all works it does seem superior to the flexi blade method above and both superior to manual scraping. 
I note this thread below  has a professional setup both the remover and the vacuum so that's probably the way to go if you can afford it or are happy to rent it. In my case iam only doing a room.
I note the thread below seems to speakly highly of the vacuum not clogging.  https://www.renovateforum.com/f216/f...-rgp80-113654/        *Method 3* 
just to repeat it, all of the above is an attempt to go further then axe chipping out sections as below, which many tilers seem to still swear by

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## rebuildr86

I use the axe (hatchet) alot, for kitchen splasbacks and 1.2m high bathroom renovations, but if ur going above 1.2m u must remove it all, or ull end up in the mistake i paid for. That said, the hatchet i still use alot, coz it uses less energy than holding the jackhammer. Sometimes ot just gets too heavy, and i start using a floor scraper on a pole up the walls. That also works quite well

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## DaleBlack

> I use the axe (hatchet) alot, for kitchen splasbacks and 1.2m high bathroom renovations, but if ur going above 1.2m u must remove it all, or ull end up in the mistake i paid for. That said, the hatchet i still use alot, coz it uses less energy than holding the jackhammer. Sometimes ot just gets too heavy, and i start using a floor scraper on a pole up the walls. That also works quite well

  The mistake you mention, what happened? a wall of tiles came off? how quickly did it happen though after you finished the job? 
With the rotary hammer method and the sds bit with the flexi blade, i did think its hammering the hell out of the wall as it removes the whiteset, compared to the action of manually scraping. 
 I wonder if all that vibration and hammering could also lead to the grey render starting to come off the bricks?  ie. not straight away but you have undermined the adhesion of the render.
Also when you end up the very top of the wall where the render ends and there is a small amount of exposed brick prior to the ceiling, you have to be careful that it doesnt chip away a chunk. 
Have you ever consider the grinder/vacuum method or is that too expensive to outlay on or too much time?

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## rebuildr86

I use the cup grinder with dust extraction just at the end to remove any small bits of glue, but i dont like to use it on whiteset coz it just clogs everything up.
Chipping away whiteset onto the ground and gently sweeping most of it up into a dustpan is the way to go. Then vacuum.
As for the mistake that i paid dearly for, bathroom wall, just chipped away the plaster like ppl say is ok, started tiling vertically, quite fast, with powder mastic. About 20 mins after i began, a wedge at the bottom gave way and the entire thing shifted down anout 2-4mm. I wedged it back and continued on like i would otherwise always do. But this mustve unsettled somethiing, becauase a few hours later it all just fell off.

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## DaleBlack

> Chipping away whiteset onto the ground

  with the rotary hammer and flexiblade or manually?

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## rebuildr86

Always the ozito!!

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