Self levelling over bitumen - TilersForums.com

[Alex462]

So I may have done an oopsie.

We are putting self-levelling compound down over floor where I removed the vinyl tiles. Some of the tiles had a white powder which had pushed them up. This is a concrete ground floor with no basement. So my plan was to seal over the bitumen and then put self leveller.

I have applied a layer of acrylic Setcrete High Performance Floor Levelling Acrylic Primer - 2.5L | Wickes.co.uk - https://www.wickes.co.uk/Setcrete-High-Performance-Floor-Levelling-Acrylic-Primer---2-5L%0D%0A/p/154148

However I since learned that 1) this is no good for bitumen and 2) the bitumen may have been a damp proof membrane when installed (in the 50s). So I should perhaps have used SBR?

I also read that PVA plus self leveller is a recipe for disaster, even though that is often recommended!

What do I do now? Go ahead with self leveller? Try and remove the acrylic and apply SBR instead?

I really, really do not want to grind the surface because of the dust.

 

[marbleman]

The bitumen was installed in the 50s it’s no good as it only last 40 years a a DPM
Remove bitumen and install A18 then NA at 20mm with granite chippings then install DPMc1 and then latex over top with NA latex which will give you a correct DPM all made by Adrex
Water based latex is no good on top of bitumen and no good to under side of a DPM
Install once and do it correctly and it does work we have just completed a installation using Adrex and there recommendation

 

[DanbSE]

HI, similar to what was said above, though there's also the ability to use Weber products, including Weberfloor Flex. Obviously if bitumen can be removed, then do so, but non-removable residue doesn't prevent a primer, Weberfloor Flex/ DPM solution without need of chippings etc

weber PR360

Tiling primer for preparing most substrates before applying adhesives, levellers or tanking systems

www.uk.weber

weberfloor flex

Fibre-modified floor leveller perfect for underfloor heating or wooden floors

www.uk.weber

weberfloor DPM

Two-component epoxy based damp proof membrane capable of one coat application

www.uk.weber

 

[Alex462]

The bitumen was installed in the 50s it’s no good as it only last 40 years a a DPM
Remove bitumen and install A18 then NA at 20mm with granite chippings then install DPMc1 and then latex over top with NA latex which will give you a correct DPM all made by Adrex
Water based latex is no good on top of bitumen and no good to under side of a DPM
Install once and do it correctly and it does work we have just completed a installation using Adrex and there recommendation

Cheers for your reply!

Problem is there's no real official advice available that I can find. Would have loved to see that recommendation before I got to work!

We just did the Mapei 10-40 self leveller over the acrylic. No way were we getting that bitumen crap off. House is situated high on a hill with chalk ground, so excellent drainage.

Maybe I'll have to rip it out in a few years and try again. I guess time will tell whether it's ok.