what is best to use on slate floor tiles ,glue or self leveling

[trakkad]

hi everybody I have unfortunately slate tiling throughout my house with hardwoods as well, desperately want to put laminate flooring over the top of both. I got one craving and that was to use Self levelling for 80 squares costing around $4000, Has any body had any experience or know of about a glue that pretty much does the same thing filling in the uneven floor surface, would like to have a price comparison before I book anyone in to do the job.

Thanks for your help 

[MitchellMc]

Welcome to the Bunnings Workshop community @trakkad. It's a pleasure to have you join us and many thanks for your questions about laying laminate flooring.

Slate floor tiles present a unique challenge when installing laminate flooring due to their irregular surface, potential fragility, and the sealers often applied to them. The natural texture of slate can result in significant height differences, making it unsuitable as a base for laminate flooring without intervention. Additionally, many slate tiles are treated with sealers, which can interfere with the adhesion of both self-levelling compounds and adhesive materials. Furthermore, slate is prone to chipping and flaking, which can create an unstable foundation for the new flooring. Due to these factors, even self-levellers from our suppliers are typically not recommended for use over slate, as they may not bond properly, and the slate's fragility could lead to long-term issues that will compromise the cement.

Advice I have received in similar situations is that the slate tiles should be pulled up and a self-leveller used on the underlying base concrete base.

Let me tag a few of our helpful members, @Jewelleryrescue, @Nailbag and @Dave-1, for their thoughts. 

Please let me know if you have any questions.

Mitchell

[Dave-1]

Good Evening @trakkad

Mmmm Im not sure if I am reading your post right, Are the slate tiles over timber floorboards or are they on concrete?

Whichever way Id go with @MitchellMc's recomendations as I think it would be problematic putting a self leveling compound over the slate. I have slate tiles on a back room slab that was done  mmm lets say dodgy and it really shows up how easy movement cracks and shifts the slate. 

Start with a clean slate I had to say it! lol and you will have a lot less issues overall.

Dave

[Nailbag]

Hi @trakkad 

As with @MitchellMc I would highly recommend lifting the slat, and scraping clean the underlining floor which I assume is concrete. Floating floor connecting systems are not very forgiving on any surface that has the slightest deviation in what its being laid on. Many manufacturers will state the acceptable deviation in the specs. The cheaper the product the less forgiving that deviation will be. We are talking 1-2mm!

The photos below show a tiled floor that I eventually laid a floating floor system over. Despite cross checking the top level finish with straight edges which appeared to be well within its deviation, in reality caused a lot of grief when laying the boards. In so many instances the board connecting system simply didn't want to click together and I was constantly placing less than mm spacers underneath in order to join boards together. Yes in the end, it eventually came together, but it took 5X as long and a lot of grief (#$#@!). I should have lifted all the tiles!

I have also done a floor that originally had slate down. It's a big job that I recommend hiring a decent (not too heavy) pneumatic chisel. The process will cause a significant amount of very fine and harmful masonry dust. So good quality PPE is a must. As is sealing off all adjacent room very well. The fine dust will make its way through the smallest open space and is time consuming to clean.

It will be a very labour intensive job to remove the slate and clean the underlying slab. But a few days hard labour will only cost you the hire of the tools of around $250 vs $4000 for self levelling compound which without going in to more detail will only end up in a larger can of worms including resulting in a  finished floor higher than the connecting rooms.

Nailbag

[Jewelleryrescue]

Hi @trakkad 

Has  any body considered using a  hired concrete resurfacer/grinder  (Cost $400 per 24 hours)  yes at the risk of some damaged slate tile that can be taken out filled with ordinary cement or loose slate  just reglued in place again.

Angle grind the corners and detailed sander with coarse 50 gt paper

I think it will work I used such a  machine on solid marble tiles and lowered any highs and lows egdes to a dead smooth  floor.

@Nailbag you  had  dirct experiance  with  slate will slow  grinding the state flat work?

This will reduce the slate floor to a dead flat floor remove any loosened up slate or glue them back  down might the best with builders  glue.

The laminate floor will lay right on top treat it as a concrete floor as the surface is raw stone .

[Nailbag]

Hi @Jewelleryrescue 

Yes I've used one about the size of a floor polisher and though the idea is a good one, however it wouldn't be suitable on slate. Unlike the solid marble, the machine would break away shards of layers and would be too hard to control any evenness of depth/level. A dual layer cup disc on an angle grinder is a handheld version which is extremely efficient in taking off the high-points. But again trying to manage a 1-2mm level over a wide area would be very difficult.

In my experience you can't lift slate without it breaking. If it's glued to a slab it's impossible, and if it was laid to cement sheet, they crack/break once bent.

I still think the fastest solution is to chisel them up, but then use your hired resurfacer to grind down all the remaining high-points is a perfect solution for that stage.

Nailbag

[Jewelleryrescue]

Thanks @Nailbag 

Good to know slate  dosnt  play nice.