What type of Screed / Self-leveller to use? 30mm depth req

[NHW]

Our current renovation stage has moved onto the flooring part and we have lifted up all the old flooring which was old parquet stuck down with bitumen.

There is still abit of bitumen on the floor which we are not sure if it contains asbestos so we are not going to tackle or touch it and instead have read that we can just clean and seal over with Arditex NA, which we have done with a dual-layer.

Floor is a concrete slab with DPM already underneath, the house is 1970s and hence had abit of settlement overtime and the difference between some of the high/low spots in the room are equivalent to around 30mm in variation difference.

since we are DIYing it, we are going to stick with self-levelling products due to them being easier overall to work with (but obviously more expensive).

I know that some screeds have a certain 'minimum' thickness required to stop from cracking, but my floor is quite uneven and bumpy, but the highest variation between the highest to lowest spot is 30mm. so there will be areas that will only have 10mm, 15mm, 20mm screed etc. So with that, do i then need to find a product that has a 'minimum' tolerance of my lowest point (possibly 10mm)?

 

[Mr Chibs]

Depending on room size, SLC will be expensive, most SLC's can do a few mm's as minimum, I'm sure there are some that will do up to 50mm.

3-40mm SLC.

I would paint on some 'Primer G' onto the slab before you start, it will adhere better. Thinking about it, you could SLC the low areas first, and if you are in no rush, primer again and build up in multiple applications, if you can't do it in one go.

Good luck

 

[Notch7]

sand cement screeds are really 25mm min bonded, however if a sand cement screed is made with ronascreed SBR it can used from 10mm as a wearing / levelling layer.

It needs proper preparation of the substrate to achieve monolithic adhesion.

alternatively you could look at mapei top cem.

 

[dazlight]

Over bitumen to get a good bond dont any water mix smoothing compounds. always a latex ( bag & bottle )

we always go with ardex NA with granno chips if we are building up.
other compounds a bit cheaper you could use

fball 1200 pro
tilemaster pro flow

also think about using a epoxy dpm as the old one you have might have holes in it now.

 

[NHW]

Depending on room size, SLC will be expensive, most SLC's can do a few mm's as minimum, I'm sure there are some that will do up to 50mm.

3-40mm SLC.

I would paint on some 'Primer G' onto the slab before you start, it will adhere better. Thinking about it, you could SLC the low areas first, and if you are in no rush, primer again and build up in multiple applications, if you can't do it in one go.

Good luck

Ahhhh yeah we have primed the floor with SBR as we read that is a good type of primer to use and i think moreso that it will adhere to the bitumen. Yeah we arent actually in a rush as the house isnt even ready overall and taking shape slowly, so would there be a big advantage to doing it in stages? Thank you again for the advice btw

 

[NHW]

sand cement screeds are really 25mm min bonded, however if a sand cement screed is made with ronascreed SBR it can used from 10mm as a wearing / levelling layer.

It needs proper preparation of the substrate to achieve monolithic adhesion.

alternatively you could look at mapei top cem.

yeah thats the problem we have with our floor atm, the fact that its weirdly bumpy and not just like sloping in 1 corner, its like got raises and hills etc so the minimum mm would have to be very flexible if it were to be sand/cement, and hence why we ruled that option out.

ah, so is Top Cem the replacement for the cement, as in you would still need the sand element? or is it a standalone product within itself (just mix with water), sorry if thats a stupid question lol And thanks for your response

 

[NHW]

Over bitumen to get a good bond dont any water mix smoothing compounds. always a latex ( bag & bottle )

we always go with ardex NA with granno chips if we are building up.
other compounds a bit cheaper you could use

fball 1200 pro
tilemaster pro flow

also think about using a epoxy dpm as the old one you have might have holes in it now.

ahhhhh right i got you, yeah the problem i have with finding Ardex is that its not readily available in local stores. and their stockists on their websites dont provide much contact information. But i only just realised what you meant in regards to Bag & Bottle, so i assume that these products come with their own type of mixtures etc

thank you btw, i will look into these now and see if i can get enough to be able to get the coverage i need.

room is 4.4m x 3.3m (15m approx) and assuming that im going 30mm depth (even though it will be less than this).

So 1 Bag + bottle of Ardex NA covers 5m at 3mm depth

10 Bags + bottles would cover 5m at 30mm depth, so i would need to times this by 3 in order to get 15m at 30mm depth coverage.

just trying to see if i am getting my maths right before i go and order too less or too much.

Thank you

 

[dazlight]

You can’t use a water based primer under a liquid Dpm. It isnt moisture tolerant and will debond off the bitumin.

1 unit of NA will do 1m2 at 10mm on average. Better to mix one unit with half bag of granno.