Struggling with self-levelling compound

[MyNameIsUrl]

My self-levelling compound doesn't flow to form a level surface. Any tips please?

The result is an undulating surface which can vary 10mm, from the contents of a single 20kg bag, spread over 2-3 square metres

I'm following the instructions and have watched youtube videos. I mix thoroughly with a power drill and paddle, adding compound to water, then pour and quickly use a trowel to help it flow. From the first contact with water, to leaving to flow is less than 10 mins, so I don't think it should be setting in that time. It's onto a concrete floor in a room that doesn't get sun, so not over-hot. I've tried adding 10% more water (against instructions) one one bag as a test but no great improvement. I've tried keeping the water in the fridge to slow down the setting. I'm using the recommended PVA/water mix as a bonding agent, pouring whilst tacky. The instructions give 30 mins pot life and 2 hours set time, but mine has a dull 'dry' finish in well under an hour and just doesn't seem to flow at all. The compound I'm using is intended to be laid in layers up to 6mm, but I can't get a level with that regularity to start building up gradually - I'm having to shave off high spots after each pour.

My proposals are (1) try 20% extra water to make it more fluid (2) use an impermeable undercoat such as BAL APD acrylic primer and leave to dry to ensure moisture isn't being prematurely sucked from the mix.

[sg31]

The concrete floor is sucking moisture out of your mix before it has time to flow and self level. The cheaper brands are more prone to this, the expensive ones less so. You could sort the problem by pre-wetting the floor or seal the floor with something like PVA

but I've been retired for 5 years now and I can't remember which brands are best. As I said earlier It tends to be the more expensive brands. You get what you pay for.

Which of the other methods you choose will depend on how fast you need the floor to dry out. Obviously if you throw a couple of buckets of water down you won't be able to put carpets down the next day.

[AsleepInYorkshire]

My self-levelling compound doesn't flow to form a level surface. Any tips please?

The result is an undulating surface which can vary 10mm, from the contents of a single 20kg bag, spread over 2-3 square metres

I'm following the instructions and have watched youtube videos. I mix thoroughly with a power drill and paddle, adding compound to water, then pour and quickly use a trowel to help it flow. From the first contact with water, to leaving to flow is less than 10 mins, so I don't think it should be setting in that time. It's onto a concrete floor in a room that doesn't get sun, so not over-hot. I've tried adding 10% more water (against instructions) one one bag as a test but no great improvement. I've tried keeping the water in the fridge to slow down the setting. I'm using the recommended PVA/water mix as a bonding agent, pouring whilst tacky. The instructions give 30 mins pot life and 2 hours set time, but mine has a dull 'dry' finish in well under an hour and just doesn't seem to flow at all. The compound I'm using is intended to be laid in layers up to 6mm, but I can't get a level with that regularity to start building up gradually - I'm having to shave off high spots after each pour.

My proposals are (1) try 20% extra water to make it more fluid (2) use an impermeable undercoat such as BAL APD acrylic primer and leave to dry to ensure moisture isn't being prematurely sucked from the mix.

The term self levelling can, dependant upon the product be a little misleading. It's been a while since I've used any but I seem to recall it did need to be lightly troweled. And 6mm layers does seem quite a lot. I thought they had to go down in 3mm layers. Again I suspect that differs by product. What's the product called please?

AiYn'U

[MyNameIsUrl]

What's the product called please?
AiYn'U

It's Everbuild 708 Febflor Universal - not a brand I'm familiar with, but it seems to be associated with Sika which is a good name. Not that I'm blaming the product, I'm asuming I'm doing something wrong.
Data sheet: https://www.everbuild.co.uk/wp-content/ ... 2020-1.pdf
I'm using their recommended EVERBUILD PVA diluted 1:3 with water on concrete as a primer.

The term self levelling can, dependant upon the product be a little misleading. It's been a while since I've used any but I seem to recall it did need to be lightly troweled. And 6mm layers does seem quite a lot. I thought they had to go down in 3mm layers.
AiYn'U

Different products have different specs - some is 'deep fill' up to 50mm, presumably for sloping or cratered floors. It would be out of the question for me to attempt a 3mm layer as it doesn't flow, and the previous layer varies by up to 10mm.

[stewamax]

Apply with a trowel, but professional laminate layers afterwords use a spiked roller* on a broomstick to remove air holes, smooth the surface and break up any clumps.
And use a latex-based screed: I have had good experience of using Ardex Arditex NA
I have always sealed concrete with PVA before applying the screed. This may be overkill but, like plastering, you definitely need to wet the concrete first to stop the screed drying patchily and too soon.


* Screwfix etc sell them for around £20. Sometimes called a 'porcupine' roller

[Mike4]

My self-levelling compound doesn't flow to form a level surface. Any tips please?

No help to you but back in the day when I used to use it, "self-levelling compound" used to be a misnomer. If one read the packs, they never actually used that term. On checking, they normally actually used to say "self-smoothing compound".

"Self-levelling" used to be a misleading colloquialism that lead to unrealistically high expectations. Have things changed and you pack claims to 'self-level'?

[MyNameIsUrl]

"Self-levelling" used to be a misleading colloquialism that lead to unrealistically high expectations. Have things changed and you pack claims to 'self-level'?

Oh yes, it says 'self-levelling compound' on the bag.

And after watching a few youtube videos, I accept that it initially needs a bit of help with a trowel or it shows a bit of a 'surface-tension' effect and doesn't creep forward on the floor fast enough. But in the videos, it flows enough after spreading to even out the trowel marks. Not for me though, I'm doing something wrong...

[Mike4]

"Self-levelling" used to be a misleading colloquialism that lead to unrealistically high expectations. Have things changed and you pack claims to 'self-level'?

Oh yes, it says 'self-levelling compound' on the bag.

And after watching a few youtube videos, I accept that it initially needs a bit of help with a trowel or it shows a bit of a 'surface-tension' effect and doesn't creep forward on the floor fast enough. But in the videos, it flows enough after spreading to even out the trowel marks. Not for me though, I'm doing something wrong...

Hmmm back in the day we used to have to mix it up so wet it was remarkable that the liquid ever went solid, but it did. Try adding more water....

[AsleepInYorkshire]

"Self-levelling" used to be a misleading colloquialism that lead to unrealistically high expectations. Have things changed and you pack claims to 'self-level'?

Oh yes, it says 'self-levelling compound' on the bag.

And after watching a few youtube videos, I accept that it initially needs a bit of help with a trowel or it shows a bit of a 'surface-tension' effect and doesn't creep forward on the floor fast enough. But in the videos, it flows enough after spreading to even out the trowel marks. Not for me though, I'm doing something wrong...

I have to say I'm not sure what the problem is. This does need levelling with a trowel, therefore, strictly speaking it's not self-levelling compound. And you can only work in 6mm layers. Some products will allow a greater depth but, if I recall correctly you have bulk it up with sharp sand. This isn't such a product. It does also advise after 3/4 to 1hr applying a sprinkling of water to "trowel off" any high spots.

However, from what you've said this stuff isn't mixing up - are you adding the powder to the water in incremental steps? I'm assuming you are. It sounds to me as if that's where the problem is though. It should look like yogurt or perhaps a little less thick. If it's not creamy enough it will not spread out. How are you mixing it? By hand? Apart from being hard work it may leave smallish clumps not dissolved properly enough. You need to mix with a plasterers paddle attached to your power screwdriver.

Are you laying a large area? Are the bumps appearing between the areas where different batches are being laid as this could create "humps"?

Assuming all the above is just going over old ground for you then I would check how old the material is. The shelf life appears to be 9 months.

AiYn'U