Floor is a bit of a mess - levelling compound approach?

[YorkshireMidge]

I'm refitting a bathroom for my parents. I was originally going to use Ardex NA to level the concrete floor. But when I've taken up carpet and old floor tiles and had a spirit level on it, the floor turns out to be a bit of a mess of sections/levels/slopes, and much worse than it originally looked. It looks as if the "concrete floor" is large pre-cast sections like giant paving slabs its so uneven.

See diagram below.

As you can see, the most significant slope is a reasonably linear one down towards the door from the high point, and the drop in height is around -23mm over the length of the bathroom - which is about 2.5M, and 1.5m wide.

I'm after suggestions from those of you who might have done something like this on what combination of levelling compound type/brand and approach is best for a job like this. I've never done a level to this sort of depth before.

Obviously, I'd like to do this in one pour if possible but I'm thinking the slope direction, bed depth and constraints below are going to make that a little difficult and I can afford to take a bit of time to get it right.

So, my current thinking is to put a batton up the middle of the bathroom floor and level the shower/sink side close to its full depth in one pour as there will be no foot traffic at the deep end, the sink end ought to set fast enough sloping from the high point to -5mm deep, and I've got full reach to trowel the compound out if necessary without wading in it. When that side is set solid, do the loo side in two or three stages. Then do a final thin level across both if needed.

Constraints:

I'm only concerned with time to walk-on. The flooring on top of it can wait (this will be non-slip vinyl).

The new shower tray is a raised/cast one and must be on a level surface + the waste pipe has to go along the right hand wall. i.e. I have little option but to try and sort the levelling issue out so the waste pipe slopes in the right direction!

It isn't feasible to move my parents out due to their health situation right now (part of the reason for the bathroom refit and why I'm doing it) so I have been working around them. This is the only bathroom/toilet - but we do have a chemical toilet setup in a spare bedroom which has been useful when I was fitting the new toilet and sink. That's far from ideal though so I'm looking for a walk-on time of around 3 hrs.

Thanks!

 

[mcprinter]

DIYer and have only used SLC once for a 30mm lift.
Mapei 3240 (3 to 40mm) worked well.
I think it took a few hours to set enough to walk on.

I had some dips in the 3240 when done and used Mapei 1210 (1 to 10mm) to fill and feather out.

I used Setcrete SLC primer as it was available in a smaller size than the Mapei primer.
Fischer resin was great for filling cracks and holes before the pour.

Mine was a concrete slab in an extension that had settled over 20 years.
How is a 23mm lift going to affect the doorway to your parents hall/landing? I am assuming the door is bottom left of your pic?

 

[YorkshireMidge]

How is a 23mm lift going to affect the doorway to your parents hall/landing? I am assuming the door is bottom left of your pic?

Good point - and I had a look at that today and I think it should work out OK. They have just had a new carpet in the hall which, with the underlay too, is much thicker than the old floor covering it replaced - so it should end up roughly level. The gap under the bathroom door is already generous enough to pass over the new floor level - though I might have to shave a bit off when the flooring is added on top.

Thanks.

 

[YorkshireMidge]

Just an update on this posting if it helps anyone else working with similar issues/contraints. I decided to go with priming using BAL Prime APD, then BAL Level Max leveller on the basis that I've been using BAL products over the years and not had any problems, and this stuff seemed to be rated by the trade in spite of it being a bit more expensive than some. I actually found it pretty good to use, and would be happy to use it again. It was set pretty well at three hours even given the depth.

I ended up doing this in two halves which was far from ideal but it seemed the best way with me working on my own and not knowing how the leveller was going to behave and set. The result was pretty good considering, but I'm mulling over doing a very thin layer on top just to get it spot on, as I have some imperfections in it as a result of delays as I mixed up the next bag (my fault, not the product).

With the benefit of hindsight, I would do this differently. My concern that the slope was steep enough for me to end up paddling in it before I managed to trowel it out was justified when I saw how each half flowed. However, I have since found out that you can get strap on foot plates for your boots which have 25mm spikes and allow you to walk in freshly poured levelling compound without disturbing it too much. Assuming these work well, I could have done a pour across the entire floor, in two stages and saved myself some effort.

I also wouldn't attempt this on my own again. If you need more than one bag of leveller at each stage as I did, you really need someone to be mixing the next as you're pouring the first.

For the batten, I actually used short sections so I could follow the imperfections in the floor, and put duct tape on the leveller side so they would come away from the leveller easily. So didn't need to silicone the battens down.

 

[mcprinter]

Thanks for taking the time to update.
Looks like a good job

I did 7-10 bags on my own but didn't have far to carry it.

What imperfections do you have?
It doesn't need to be 100%. My click LVT spec is 2mm/M variance allowed.

 

[YorkshireMidge]

Thanks. On the left hand side, I just spent far too long mixing the second tub (it needed two per side) and when I added that to what was already down, that had started to skin over so they didn't mix together that well. It's too tempting to try and trowel it and that didn't help. So there are a couple of patches where it hasn't levelled properly that's all, probably not helped by the fact BAL Level Max is one of those with fibre in. I may be able to skim the affected patches rather then re-level.

I've since found a really good video on YouTube on using BAL Level Max in a similar sized room where they just dump the entire bag into the water and get it mixed really quickly and that's what I should have done.

7-10 bags is going some on your own - well done!

 

[mcprinter]

It was a long day for me!
Rinsed my tools into the drain. Set solid. Oops Managed to chip it out.

Mapei 1210 will do from 1 to 10mm.
VERY quick look and can't see a BAL that does 1mm
Another prime before you put any more down

 

[YorkshireMidge]

It was a long day for me!
Rinsed my tools into the drain. Set solid. Oops Managed to chip it out.

Mapei 1210 will do from 1 to 10mm.
VERY quick look and can't see a BAL that does 1mm
Another prime before you put any more down

Yeah - it will have to be a non-fibre one for sure. Good point on re-priming, thanks.