Hi all
Would appreciate any help regarding self levelling a 16m2 concrete floor.
It does need self levelling and there are in some areas dips of up to 11mm.
My plan was to using Bal multibase put a first level down of 5mm then when dry a second one and feather in to the top of the humps.
Having now done the first level i've two concerns.
1-many bubbles appeared.
Will this affect the compound?
2-i checked and noticed in one area that the depth of the slc was 7-8mm.
Will there be any consequences as multibase maximum depth is 5mm.
Quickly learning and now think i should have used a compound that allowed me to do the depth in one go and should have used a spiked roller.
Cheers
Kev

You can get a slc roller from www.tradetiler.com that deals with the air in slc. a couple of mm's over the stated thickness, hopefully that small amount won't hurt...this time!!!!!!!!

Not sure if the Bal product calls for primer but did you prime floor 1st?

Originally Posted by kaharrison9

Hi all
Would appreciate any help regarding self levelling a 16m2 concrete floor.
It does need self levelling and there are in some areas dips of up to 11mm.
My plan was to using Bal multibase put a first level down of 5mm then when dry a second one and feather in to the top of the humps.
Having now done the first level i've two concerns.
1-many bubbles appeared.
Will this affect the compound?
2-i checked and noticed in one area that the depth of the slc was 7-8mm.
Will there be any consequences as multibase maximum depth is 5mm.
Quickly learning and now think i should have used a compound that allowed me to do the depth in one go and should have used a spiked roller.
Cheers
Kev

Hi Kev,

You've answered your own questions really mate, Tradetiler has just added the spiked roller to his shelves.

Trade tiler

One thing ive learned is to mix it a bit thicker first, ie do not add all the latex and mix with the mixer on lowest speed to a smooth paste with no bubbles, then add the recommended amount to get your desired consistancy. Ive forund i get few if any bubbles and can speed up the mixer towards the end.
I used to mix it all together in one go. Hope this helps, might be worth a try!

The Odd air bubbles don't hurt nowt..unless you were laying vinyls or summit....and need a 100% smooth substrate...

A topps client decided to level his floor with toppfix...............I just stood there and died..................

Invest in a spiked roller........I have and don't regret it............need a mirror finish ? This will do it

You can get bubbles in SLC from pouring directly onto concrete without priming, even with "primer free SLCs; as the SLC and moisture penerates the pores of the concrete, air escapes into the SLC, hence bubbles... "Primer free" SLCs minimize that risk, but it does still happen. If there isn't a good reason to not prime before pouring SLC, it is usually a good idea to prime.

Thanks to all
I did prime the floor-bal apd.
Will be speaking to trade tiler tomorrow about buying a spiked roller.
Not the best day but have learned lots.
Cheers
Kev

Another reason for bubbles forming is mixing the SLC at too high RPM.

Originally Posted by sWe

Another reason for bubbles forming is mixing the SLC at too high RPM.

I was just about to say that. Its a common thing i see when tilers have a mixer," just put it on full speed and go for it".
When mixing latex leveller or water based follow the instructions. If its Latex then one unit of Latex to One unit of powder, mix well but not too fast as this will add air to the mix and (i believe) warm the mix up, which is not ideal.
With water based mix, add the correct amount of water as specified by the manufacturer.
Try other brands and types of levelling compound and you will find one that will suit you. I recommend the Mapei range and yes i have tried a lot of others.

BAL`S acrybase can be used up to 10mm,where as multibase is only 5mm.i`m with the guys on the mixing speed regarding bubbles..i need to purchase a spiked roller too.

Do take on board about drill speed and did look at the Bal acrybase but was quite more exspensive than the multibase.
Have now got a product list on Mapei products since buying the multibase and the Mapei ultraplan or ultraplan maxi looks like it would have been ideal.
Would it be okay to use a Mapei slc over the Bal multibase slc and if so would it be compatable with the Bal primer i've already used?
Thanks for your help
Kev

hi mate 'bubbles' come from the substrate being dry, before laying slc dampen the floor first 'not wet damp' and then you shouldn't get any if not as many bubbles

Originally Posted by woodie

hi mate 'bubbles' come from the substrate being dry, before laying slc dampen the floor first 'not wet damp' and then you shouldn't get any if not as many bubbles

Some SLCs, especially rapidly curing ones, do not react well to the substrate being damp. It's best to simply follow the manufacturers instructions, but as a general rule, it's doesn't hurt to prime.

I actually thought that the bubbles were caused by air entrapment when mixing...

Woodie can you elaborate more on your theory please...

i was informed that the slc obviously dampens the concrete causing it to release air that is trapped in its surface so by dampening the floor first you release this into the air instead of into the slc i didn't dampen the floor when i first laid the stuff hence i had air bubbles everywhere since then i don't get any trouble

1st ive heard about dampening floor proir 2 layin slc..!!!!
bubbles usually appear because off mixing at high rpm ...

considering my mixer is called my arm i can't see that

Pouring SLC directly onto concrete, which is porous, ie absorbant, lets the concrete absorb some of the water in the SLC, which pushes the air in the pores out, into the SLC. Hence, bubbles.I've observed similar things happen to plaster and some adhesives. The water acts as a low tech primer substitute, filling the pores, if temporarily.

Essentially, wetting the substrate before pouring SLC or whatever onto it, feeds the substrate with water, pushing the air in the pores out, so that when you pour SLC onto it, the air in the pores is already (mostly) gone. But watch out, not all SLCs react well to the added water. Some rapidly curing ones can crack as they cure.

Using the old concrete/cement method of laying tiles, you usually wet/slurry the subsrate first to better the adhesion, excessive drying through absorbation, etc.

Originally Posted by sWe

Pouring SLC directly onto concrete, which is porous, ie absorbant, lets the concrete absorb some of the water in the SLC, which pushes the air in the pores out, into the SLC. Hence, bubbles.I've observed similar things happen to plaster and some adhesives. The water acts as a low tech primer substitute, filling the pores, if temporarily.

Essentially, wetting the substrate before pouring SLC or whatever onto it, feeds the substrate with water, pushing the air in the pores out, so that when you pour SLC onto it, the air in the pores is already (mostly) gone. But watch out, not all SLCs react well to the added water. Some rapidly curing ones can crack as they cure.

i was hoping someone would find the right way of saying it, my brains not quite functioning properly tonight

Thanks guys......i prime , so don't have probs with air pockets....but mixing at too high a speed with a paddle mixer entraps air as well.......so a combination of both would deffo cause this...

Originally Posted by Dave

Thanks guys......i prime , so don't have probs with air pockets....but mixing at too high a speed with a paddle mixer entraps air as well.......so a combination of both would deffo cause this...

cheers Dave i'll keep that in mind because i've been considering buying one of those things for a while now

Originally Posted by woodie

i was hoping someone would find the right way of saying it, my brains not quite functioning properly tonight

It's friday, no one's going to blame you

Originally Posted by woodie

cheers Dave i'll keep that in mind because i've been considering buying one of those things for a while now

You refering to a paddle mixer? Highly recommended. It'll save ALOT of time, and you'll get a more homogenous mix. Buy one with High wattage and high torque though, because you want to be able to mix at relatively low RPM to avoid trapping air. You can't go wrong with Collomix, Festool, Flex, or Rubi. Remember that different paddles are good at different things.

Cheers all for your experiences and experience.
Hopefully back on track.
Spoke to the Mapei technical dept and very helpful.Suggested using ultraplan slc over the bal multibase to level the floor,it goes from 1-10mm and use the Keraflex maxi 3-15mm bed and doesn't set as quickly,allowing myself a bit more time.
Have ordered a spiked roller from trade tiler,will certainly be on low revs when mixing and follow instructions regarding damping.
It does actually say on the multibase to prime,allow to dry then dampen the substrate.
Dave mentioned he is looking into suppliying spiked soles as well.
Is there a specific paddle swe for slc?I used my adhesive paddle.
Kev

Generally, adhesive paddles work quite well on SLCs, but some, specifically the thin flowing/semi-liquid ones, need paddles which generate higher sheer forces to avoid lumps. They can look like this:



But it varies. Generally though, you'll be ok with an adhesive paddle, as long as you take your time to mix it properly.