Dpc Under Hardiebacker - TilersForums.com

[Ben_A1990]

Im not an expert in DIY, but they dont seem like vinyl. They are hard.

 

[White Room]

They used to heat them when cutting then fix because they were rigid.

 

[Ben_A1990]

Just lifted some more of the green stuff out of the way. The edges of some of the tiles have cracked by the skirting board. I am 99% sure they are not vinyl. When I scratch the edge with a screwdriver they create dust and do not peel in any way.

Going back to the original question. Do I need any DPC under hardie backer with these surfaces?

 

[White Room]

The age they are you'd best check there not the ones that contain asbestos.

 

[Qwerty]

No, you don't need any DPM.

Both floors you have have got laminate foam underlay as @Andystiletiling said. This can just be thrown away. I was also right (in a roundabout way!) in that you have old Marley thermoplastic tiles which are stuck down with bitumen (black) adhesive. These are brittle and if they are breaking up near the perimeter then it is a pretty good sign most others will soon follow suit. They usually contain very low grade asbestos but check with your local waste disposal site to check that they accept these, most do in local landfill. Take care when removing for dust etc and most usually come up whole or near whole.

You don't need hardiebacker from what I have seen, but could benefit from slurry coating over the whole floor where bitumen adhesive is present and tiling that.