Tiling new splashback over existing one

[Former Workshop member]

G'day everyone,

I think I am OK to go but still would be happier if any general handymen or tilers could give me a 'yeah...sounds good' or 'no way mate, you need to do <whatever>'. For what it's worth 'handywomen' are welcome as well; I just assumed that was implied.

I have decided to retile the splash back of my kitchen. I have experience tiling with a mate for a few days and then doing the job to a number of previous houses; so the tools and skills I am OK with. However the substrate is the one that is a bit different so I want to check here.

Some of the area (see the picture) was tiled and some was painted. After some research I believe that tiling over paint is asking for trouble so I have stripped it back (with a 40 grit belt sander...very carthartic ) to mostly float coat/render coat (the grey stuff). I also was left with the impression that 'white set' was fine to tile over as well...as long as all surfaces are cleaned AND WATERED prior to starting the job. A few queries I would appreciate a word on:
1. i intend to do a 'skim coat' (proabably wrong thing to call it sorry) of tile glue with the flat side of my notched trowel - reasonably thin 3-5mm max - to make sure some of the divots of render that came out are filled and to give the wall a flat surface to then tile on. I did it this way with my mate and also have read that it is an OK approach...does anyone see any problem with that? Obvious reason is I have a big bag of tile adhesive and no other tiling jobs...so I may as well use it here.

2. The picture shows some existing tile glue that was part of the previous splashback (above the stove top). I have chipped off the pieces that were too proud to allow an even 'skim coat'; however should I take it all off (back to the render) or is it OK to put new tile glue over existing?

3. Do I need to prime this surface? This one has confused me as manufacturers (Davco etc.) say that all surfaces should all be primed...yet a forum I read said that if you are at the float coat/white set stage and you prime the surface it can react with the tile glue and become a gluggy mess resulting in your tiles sliding down the wall.

4. On the tile adhesive I bought UltraFlex from Funnings as I believe it was what I used before (it has been a while so I'm probably wrong); but the Davco website is telling me Mastic is what I should be using. Easy enough to change over if there is an appreciable difference.

My intended methodology is to clean the dust off of the wall, give it a wipe off, give it a light spray of water (as the render has been there 2.5-ish years it would suck all the water out of the tile adhesive otherwise), do the skim coat (of tile glue NOT render) to provide a flat surface, then proceed with double checking my set out and tiling like normal. Tiles are 300x100 with a 3mm spacing. 7 rows high across the rear wall and 600ish down the return walls. Actually I will include a CAD plan I did of the tiling...it is rough and includes the eventural rangehood and shelves that will follow on from the tiling so I hope it is not too confusing. I have put a level (I think I have a laser somewhere but I can't find it!) and a straight edge around all the walls and planned it all out...I am pretty comfortable with that; it is just the substrate that I am concerned about.

Any tips or suggestions from any ladies/gents here would be greatly appreciated!

Cheers guys,

The CaptainThis photo is taken from roughly the same viewpoint as the CAD drawing photo has been

Closer look at the render and white set and tile glue sectionOnly included to show the finished concept (ignore the range hood and shelves above)

[gippslandhome]

G'day @Former Workshop member . Seems very scary at times but it's pretty simple.

Firstly I would recommend getting the old glue and white set off. As the new glue dries under the tiles it can tend to pull off the existing white set or glue.

Once you have got as much off as possible then definitely prime your surface. The only time primer will go a white gluggy mess is if you start tiling when the primer is still wet..

Priming over a dusty surface is essential.

Doing a skin coat of glue is a good idea to get the surfaces flat.

What we used to do is work out the deepest spots circle them, notch trowel the area and with a level screed the glue flat then steel float it with the back of your notch trowel.

Then allow the glue 12-24 hours drying time before tiling. 

As to set out.  The best way is to find centre. Then step out with your tile from either the edge of your tile or centre of your tile and see what cut works best.

If you have measured centre you only have to step out either left or right, not both as the centre measurement with give you equal cuts if that makes any sense.

As a floor and wall tiler and having been in the construction industry for 27 Years I find it easier to do than write dorn but I hope you get some pointers. Feel free to message me at any stage of your project.

All the best

Kind regards Rob 👍

[redracer01]

Resaflex is the most forgiving tile adhesive you can get. It has the highest tolerance for movement and has the most polymere content in the market. Just make sure to use the correct height for your glue trowel and follow Robs excellent advise on the prep n follow through. Goodluck and post the artwok when your done.

[Jason]

@ProjectPete might also like to add to this discussion as he has plenty of experience with tiling.

Jason

[Former Workshop member]

Sorry for the delay in replying guys...I have a number of renovations going on and my attention was shifted from this to another job...fairly glad I left it for the weekend and posted this though!

My thanks @gippslandhome and @redracer01...especially gippsland that is a fairly concise run down of what to do! Definitely will help me finish the job!

Just as a side note: I kind of wish responses like this could be 'stickied' on Australian 'google searches' or something similar. Bunnings DIY vids are a really great start but I have found they tend to skip over a few points; conversely specific forums are sometimes less than 'beginner friendly'. I may 'pay that forward' with a current music studio 'sound proofing' job I am doing...

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@gippslandhome wrote:

G'day @Former Workshop member . Seems very scary at times but it's pretty simple.

Firstly I would recommend getting the old glue and white set off. As the new glue dries under the tiles it can tend to pull off the existing white set or glue.

No problem getting the white set off - I think I mentioned I used a belt sander (not sure that it is the right tool for the job)...? Whether or not; it made mince meat of the paint, white set and render (use a vacuum cleaner attachment; trust me). I used an Ozito 20 litre wet/dry vacuum (yes they're cheap but work well for mine *shrug*) but my kitchen still looked like a set from ScarFace...just intended as light humour but understood and apologies if that gets admin blocked  

The tile glue though...well I will certainly defer to your expertise and remove what is there 👍 

My concern with the existing tile glue was more whether a NEW tile adhesive would stick to the OLD tile adhesive. The existing tile glue is stuck to the float set like 'superglue' so I figured it would suffice as a pretty solid substrate. No problem though - it's great having the big green one stop shop less than a 90 second drive away! - so I'll get a bolster and probably a gimpy as well. EDIT: I believe Bunnings call them 'club hammers' to avoid possible offense - certainly none intended by me - that's just what they were always called on site.

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@gippslandhome wrote:

Once you have got as much off as possible then definitely prime your surface. The only time primer will go a white gluggy mess is if you start tiling when the primer is still wet..

Priming over a dusty surface is essential.

Doing a skin coat of glue is a good idea to get the surfaces flat.

OK; no problem...putting a primer coat down it is...just one question...

...which one? Apologies if this is a ridiculous question but the Davco website didn't really tell me definitively which was applicable. Ultrabond, UltraPrime, PrimeX...?

Cheers to @redracer01 for the suggestion on the 'Resaflex'; the reasons you listed were exactly the same reasons I bought the Ultraflex (high tolerance for movement and high rubber polymer modifier). I have no idea what brand it was that I used back when I did it but I remember being told by <whomever> that the rubber modified stuff was the way to go. Happily swap the UltraFlex for the Resaflex...only with the same query. What primer is appropriate?

Appreciate the nod of approval in terms of using the tile glue as a skim coat to straighten the wall up...if I could just get a 'heads up' on which primer to use then I will be off and going

Greatly appreciated gents - I think I am the same as most people here - I have skills enough to have a go at stuff like this...just the last few bits of advice make the difference between doing it twice or not.

Cheers
Josh

[gippslandhome]

Good morning @Former Workshop member 

I'm really glad that myself and @redracer01 were able to give you some good points to consider.

I have to say that we all really benifit in this community with a vast array of knowledge and skills.

This is out of all the communities I've joined the most helpful, respectful, no nonsense and rewarding community to be apart of.

Thank you for your encouraging reply.

All the best with all your projects.

Kind regards Rob 👍

[Jason]

Looking forward to seeing that soundproofing project @Former Workshop member.

Many thanks for the positive feedback about Workshop. We want to ensure that this stays a really welcoming, encouraging and accessible community and an informative, ever-growing resource for all home improvement projects. 

Jason

[Former Workshop member]

Yes...I have chronicled my progress up to now on my soundproofing project and I have wanted to put it on a forum somewhere to possibly guide some others...I don't know how much use it will be; but at least here people are friendly! Not so on the 'audiophile' forums...my my. 

Firstly though I may change this post around into a sort of 'how to' as there are a few differences between @ProjectPete 's effort and mine that may assist others

Peace

[Jason]

Great, many thanks @Former Workshop member.

Feel free to Start a new discussion with a subject like How to tile a splashback - I'm sure it would be very popular and be something that we could promote across the site.

Jason

[redracer01]

Prime X is my go to primer for starting out your wall. Most of the tradies I've delt with recommend the product. It is DIY friendly and again easy to use. But like any primer read the instructions at the back so you get the timing for the layout correctly. Too early and the primer will not be hard enough. Specially in this cold weather at the moment. You may have to give it extra time to dry off so that the primer sets and you can then proceed.