question on self levelling compound

[gav39]

Hi all,

I have a question about applying self levelling compound. I recently had a floor levelled in my property. The flatness achieved is poor.

My understanding is that self levelling compound needs poured within a couple of minutes of mixing with water, or certainly very quickly after mixing.

In my case it was poured over a 25 minute period after the mixing with water. By that I mean the dry powder was mixed with water outside the property. The first of 3 pours from the one large container was approx 10 mins after that. The second pour was maybe 7 mins after that and the final pour of the final mix 7 mins after that.

What I am trying to work out is whether or not it seems likely that the compound was beginning to set towards the end of the pouring process. If so, is it likely that that was what created a very non level result.

I can only guess and hope someone with experience can give me a view.

Thanks

Gav

 

[Doggit]

Each pour has taken too long, but it's very likely because SLC doesn't actually level itself. Is the uneven level all over the area, or only in certain areas that would equate to one of the pours. can I assume that you've only used 4 bags of SLC, or did you mix more than 1 bag at a time

 

[gav39]

Hi @Doggit
I thank you for the post.

Is the uneven level all over the area, or only in certain areas that would equate to one of the pours

That's a good question. The central pour is a darker colour and quite high relative to the 2 other lighter areas. (The room is small: 6square metres.) It seems to be the most uneven. In some places the flatness is the floor comes away from the wall is good - but only for a foot or so.

Each pour has taken too long, but it's very likely because SLC doesn't actually level itself. Is the uneven level all over the area, or only in certain areas that would equate to one of the pours. can I assume that you've only used 4 bags of SLC, or did you mix more than 1 bag at a time

I stayed out of the tiler's way during operations guessing I would only decrease the chance the process would work well. The mixture was created
outside and carried up in a large container. The tiler didn't return outside for more mixture. My understanding was that 2 bags were used for the process. The height in the place where I can roughly measure it is 8mm suggesting to me that we used 2 bags.

very likely because SLC doesn't actually level itself

Can you elaborate here please?

G

 

[Doggit]

6sqm, and it took over 20 minutes sounds odd; he should have done that in 2 pours/bags, and by virtue that the colours are different, it suggests that he didn't mix a full bag each time. The lighter areas have more water, and the darker area in the middle hasn't settled properly.

Self leveling compound is sludgey, so needs moveing around; now someone experienced will see how the stuff settles, and trowel it back and forth as necessary, but someone inexperienced needs a point to level it to, so you set the screws in the floor with a spirit level, and as you move the SLC, you make sure that it's settling to the height of the screws. You can add a bit more water to the mix, and that helps it settle better, but if you add too much, and then the compound settles to the bottom, and water rises to the top, so you get a weak powdery surface that need scraping off.

You need to decide whether you have enough clearance left to add another bag or so, or whether you need to sand down or scrape the high points off, but I'd tell the tiler that you're not happy with the job. If you go round the floor wth a spirit level, what's the difference in height.