Ashpalt/Bitumen - lack of DPM? - Preparation for tiling. - Tile Advice

[SB1234]

Hi all, I am looking for some advice please.

We are due to have our hall and kitchen tiled, some of which needs levelling. Our tiler is going to level the areas that need levelling. He said he is going to use Trim/Co SX301 for the levelling?

In preparation for him doing the work, we have removed some old tiles (that were under carpet and lino) that had been stuck down with asphalt/bitumen. We are therefore now unsure as to whether the house (built around 1959) has a damp proof membrane installed in these areas.
We plan to have a liquid damp proof membrane laid to combat this, and then self-levelling compound.

We have spoken to our tiler for advice but he said he does not know about damp proofing.
So...
Can you use liquid damp proof membrane straight on top of the concrete that has had asphalt/bitumen on – there is not a thick residue/layer left on the concrete?
Is it possible to tile straight onto damp proof membrane or must a self-levelling compound be used prior to tiling? Or does it depend on the product used?

The tiles being laid are porcelain tiles (60x60) so the product(s) will need to be compatible with porcelain tile adhesive.
Someone has suggested Ditra matting - would this combat the lack of damp proof membrane - does it have damp proof properties?


Does anyone have any recommendations on which products to use, and the correct process? And do you think the tiler should know about this or is that normal that he doesn't?

Would much appreciate any help / advice you can give me. Many thanks.

 

[Qwerty]

Before you go wasting your time and money on tanking (waterproofing) your floors, you need to ascertain if you have a damp proof course in your home. This should be evident from outside by a layer of bitumen protruding from between the first few layers of bricks.
The bitumen adhesive on the floor that you describe was used to fix the old thermoplastic floor tiles.

Do you have any photos of it please?

 

[SB1234]

Hi, thank you for your reply.
Yes we do have a damp proof course (in our cavity walls) but are suspecting no DPM.
Yes, I will take some photos later today and post them.
Thank you.

 

[Qwerty]

Usually (but not always) a damp proof course means a DPM is present. In older properties this can break down. I own a 1960's bungalow and when we first moved in we found it had an old fashioned very brittle bitumen DPM which had failed in a number of places. There was evidence of damp in places and the whole slab was damp. I removed all carpets and tiles (including old Marley thermoplastic tiles), dried out the floors, slurry coated over bitumen residue and then used a commercial waterproofing product over all floors and up the walls slightly. No further issues since and that was 10 years ago.

 

[Flintstone]

I would be supprised if there was no dpm in a house of that age! The bitumen was used to stick down a lot of old vinyl, asbestos type flooring, it might be that your seing

 

[Flintstone]

It you wanted to do it anyway to be certain, I would call or get your tiler to call Tilemaster tech line and get them to tell you exactly the best way to do it, which order to use there products, they make everything you would need for this job