Prep work insulated boards

[Enrique volta]

Hello every body. I've been our of tiling business for years just start a mear to work in it again and trying to take bigger jobs step by step, all has change a lot and I'm trying learn as quick as I can. The question, I have to tile 40 sqm aprox porcelain tiles, not know size yet but nothing not to big at the moment, on top of an old concrete that looks paint in black ( bitum?) On top of probably 20mm jakoboard , my questions , how to deal with this "paint ", looks thin, decoupling membrane on top of the jakoboard ? Joint for contraction? Thanks in advance ! One never have to stop learning !

 

[Dan]

I'm pretty sure that bitumen type stuff you can self-level over and tile. @Dave am I right mate?

Welcome back to the tiling trade @Enrique volta

 

[Dave]

Hello every body. I've been our of tiling business for years just start a mear to work in it again and trying to take bigger jobs step by step, all has change a lot and I'm trying learn as quick as I can. The question, I have to tile 40 sqm aprox porcelain tiles, not know size yet but nothing not to big at the moment, on top of an old concrete that looks paint in black ( bitum?) On top of probably 20mm jakoboard , my questions , how to deal with this "paint ", looks thin, decoupling membrane on top of the jakoboard ? Joint for contraction? Thanks in advance ! One never have to stop learning !

Any pics ?

 

[Enrique volta]

I'm pretty sure that bitumen type stuff you can self-level over and tile. @Dave am I right mate?

Welcome back to the tiling trade @Enrique volta

Thanks! Is what I was thinking. Next week I will go to have a look again and I will take a sample to inspect.
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Any pics ?

thanks ! I will go next week and I will take pictures, I will chisel some of the concrete and the paint to inspect it properly.

 

[Ben-gee]

Bitumen is funny stuff, I have had success with the following method.

Slurry coat of SBR and cement powder. Leave for a bit but whilst still tacky apply a decent quality self levelling compound.

Worked for me.

I know of a few failures where people have gone straight onto bitumen with self levelling...

 

[Enrique volta]

Bitumen is funny stuff, I have had success with the following method.

Slurry coat of SBR and cement powder. Leave for a bit but whilst still tacky apply a decent quality self levelling compound.

Worked for me.

I know of a few failures where people have gone straight onto bitumen with self levelling...

Thanks! On Saturday I'm going to have a proper look at it and chisel up a bit of the flooring. I will post some pictures of the paint/bitumen and of the base . Thanks again !

 

[Enrique volta]

Hello again. I went to the job yesterday and I make a couple of holes. Looks like a screed , old, dry and sounds solid. The paint looks like bitum, most of it is like 1mm thick, a couple of small patches is like 3 or 4 mm.
The "bitum" is well stick to the screed, bit in few areas is easy to remove with the chisel and no effort, should I remove it, sand it?
For primer , what would be the best ?
About the insulation board I convinced then that is not worth it without ufh. We going to go with ditra uncoupling membrane.
They have a floding recently, probably more in the future, should I treat the membrane as it was for a wet room and waterproof the joints? My concern is trap moisture will try to evaporate through the joints and make a mess in the grout, and as ditra 25 has vapour evacuation if is one waterproof unit it will evaporate through the perimeter, don't know if is worthy or is a waste of time and money.
Any advice would be great, and thanks a lot in advance!

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By the way tiles are porcelain 560 by 560 . Thanks !