Tiling concrete floor with bitumen residue and no DPM

[JT101]

Old pre 1960's house with a concrete ground floor. Unlikely to have any DPM.

I'm looking to tile the floor, which currently has parquet on it, bonded to the concrete with a bitumen adhesive.

Test scraping the floor it seems I can get all the ridges off quite easily, but inevitably, there will still be a bitumen stain on the concrete surface, but it will be clean and hard surface.

From what I can gather from various forum posts, Arditex NA is a self levelling compound that will happily go over bitumen.

However, I wonder whether a DPM will be necessary. I guess I could buy a damp meter and check the moisture content or er on the side of caution and install the DPM anyway. This is an old concrete floor, so no residual moisture in the concrete from the drying process, but I guess could be coming up from the soil underneath. No visible signs of damp patches.

Seems Ardex does a product that goes under the Aditex NA compound, but it is expensive. But then I've read that if I bought another liquid DPM and put that on the compound, that tile adhesive won't stick to it.

I plan to use Ditra matt aswell, and then install ceramic floor tiles on top.

So to summise, what is the best make up of a floor that can stick to bitumen residue, prevents damp problems, and sticks tiles and Ditra matt to the floor?


Thanks

 

[JT101]

Incidentally, I've looked at a few other threads, and the solution seems to be a levelling compound - DPM sandwich.

So the procedure would be as follows

1) Remove parquet
2) Remove bitumen adhesive as best I can
3) Apply Arditex NA self levelling compound
4) Apply Ardex DPM 1C
5) Apply Arditex NA self levelling compound
6) Apply primer or SBR
7) Apply tile adhesive
8) Apply Ditra matt
9) Apply tile adhesive
10) Lay tiles
11) Grout

Well, I know this will cover all the bases of cracking & movement, moisture etc etc, but I work my time at about £20 per hour, plus all the extra materials and I'm coming at around £800 for 6m2 due to all the different steps, cleaning up etc etc, coming back and forth to site as the different layers dry etc. And that's without the cost of the Tile, adhesive and grout which the customer will buy. The actual tiling bit I've only allowed a day for. All the rest is preparation work.
She's looking at over £1000 just to do her hallway. Admittedly tiling jobs like this run at about £30 / m2, but presumably that is literally just laying tiles on a prepared surface. £800 is a complete guess, but this is my first time working this out.

I can see someone else undercutting me quite easily and not bothering with any of the above.
This doesn't seem like a normal situation though, so maybe it's necessary. Looks very complicated