Self leveling query

[Pete]

Just got some general questions about SLC and how to make my life easier. How runny/flowable (technical terms) is the Ultra two ( @Nickfromwales ) part self leveling when mixed with the Latex? With having to bring the floor up 10mm over quite an area I was going to bulk it up with 6mm limestone pipe bedding and wondered how easy it will be to spread this? I know the best way would be to mix the aggregate prior to laying but the easier way is to sprinkle it in afterwards especially if it 10mm deep (ish).What about priming the floor beforehand as the place I am getting the compound from do not go into detail and some sites say let the primer dry before laying the compound and others say put compound down when primer is tacky. TIA

[Nickfromwales]

The only issue with fortifying a SLC with any type of aggregate / other is that it seriously loses its self levelling qualities.

What sort of area are we talking about, and is it consistently 10mm or is that an average / worst case?  

[Pete]

30 minutes ago, Nickfromwales said:

The only issue with fortifying a SLC with any type of aggregate / other is that it seriously loses its self levelling qualities.

What sort of area are we talking about, and is it consistently 10mm or is that an average / worst case?  

I suppose that is why I think do the leveling and then sprinkle in my 6mm limestone pipe bedding. I may to to do it in two pours in some areas so may use the aggregate on the lower level and just use the compound on it's own on the top. What did you think about the primer as I have been given conflicting advice. Some say PVA, others SBR of which I have some left over from another job and some get the specialist stuff, Mapei,  which is a lot more money but needs to be done right. Also, whether to let it dry before pouring the compound or leave it till it is tacky and then pour. I am thinking of using the Ultra compound that you use so any info is gratefully received. Thank you

[Nickfromwales]

You won’t be able to sprinkle anything on top after pouring the Ultra, as if anything is added it will need to have been thoroughly mixed in prior to pouring it. 

If you sprinkle anything over it it won’t be part of the floor and you’d literally be able to brush it off after.

 

If you have to purchase X qty of SLC + other then if I was you I’d just bite the bullet and go all SLC. Trust me, when you alter the SLC even slightly, you’ll all but completely lose its self levelling qualities and it’ll just be a lump on the floor that’ll require tooling into position. 

 

With regards to priming, use the Ultra primer and water it down about 75% water 25% primer and load a mop bucket with a proper janitors mop head. Mop the floor in its entirety and look for spots that dry out instantly, saturating these points as you go. Repeat that mopping until you’ve got the whole area primed. 

Immediately prior to pouring the SLC you do exactly the same again, but only mop and saturate the area you’re laying. Never let SLC hit a dry or warm floor, it must be cold and sopping wet. If you think there’s too much primer down, that’s the right amount. 

[Pete]

17 minutes ago, Nickfromwales said:

You won’t be able to sprinkle anything on top after pouring the Ultra, as if anything is added it will need to have been thoroughly mixed in prior to pouring it. 

If you sprinkle anything over it it won’t be part of the floor and you’d literally be able to brush it off after.

 

If you have to purchase X qty of SLC + other then if I was you I’d just bite the bullet and go all SLC. Trust me, when you alter the SLC even slightly, you’ll all but completely lose its self levelling qualities and it’ll just be a lump on the floor that’ll require tooling into position. 

 

With regards to priming, use the Ultra primer and water it down about 75% water 25% primer and load a mop bucket with a proper janitors mop head. Mop the floor in its entirety and look for spots that dry out instantly, saturating these points as you go. Repeat that mopping until you’ve got the whole area primed. 

Immediately prior to pouring the SLC you do exactly the same again, but only mop and saturate the area you’re laying. Never let SLC hit a dry or warm floor, it must be cold and sopping wet. If you think there’s too much primer down, that’s the right amount. 

Thanks that is what I was after. One more question, a lot of sites say you must roughen up the surface before laying primer/compound which would be a very large job. The floor is a 12 month old slab which is very clean, slightly dusty which I will hoover. When I have done this before I have just laid it on the existing concrete after SBR and never had a problem but for some reason cos it is my house I am dithering, nervousness or old age I think!!

[Nickfromwales]

Water. 

Primer. 

Mop. 

Pour SLC. 

Pub. 

?

[Pete]

2 minutes ago, Nickfromwales said:

Water. 

Primer. 

Mop. 

Pour SLC. 

Pub. 

?

?

[Pete]

I have purchased the Ultra compound and in its directions for use it says if the floor has been power floated which mine has it says it must be scrabbled/roughen up to ensure full adhesion of leveling compound to original floor. Have you used Ultra on a power floated floor @Nickfromwalesas you say just to prime it? TIA