Help - internal concrete floor slopes up to 40mm

[kandd]

Hi there,

This my first post in this forum. I apologise if it is in the wrong area

I am currently in the midst of a home renovation The concrete slab slopes up to 40mm from the centre to the outer walls.

I would like to level the floor prior to tiling but have struck a huge problem. I attempted to use a floor leveller (Lanco 173) - but approximately 10 days after it had been poured it started to lift and crack. The product was very expensive.

I have now removed the floor leveller using a jack hammer and are at a loss how to proceed. What should I do to level the floor and what is the most economical option? Any advice would be great.

Thanks
Diana

 

[grumpygrouter]

I have just had a nosey at a Lanko pdf about the product. It should only be used in one lay at up to 10mm thickness. Did you try and fill to the 40mm level? If you did that, I think may be you should have built it up in layers.

If it was too thick, you may find that too much heat has been generated when curing and this has caused the cracking. I am not sure though as I have never come across the situation before. If you can wait until some of the more experienced guys log on you will get more help.

Grumpy

 

[GazTech]

I think this is the most plausable explaination Russell, For more bulk,granite chippings can be added to mix...or level in several layers for strength.....Gaz

 

[DHTiling]

Another option on this is.. an unprimed substrate causing it to suck the moisture from the slc to quickly causing to to crack and break away or maybe to much water in the mix resulting in a weak slc.....just another thought.....

 

[Rosco0110]

You may want to try a sand and cement screed. This should sort you out. Always tend to have issues with self levelers and the heights they can level out.:hurray:

 

[kandd]

Thank you for that info... I should have mentioned that I did layer the leveller. I poured several levels building it up over several days.

I guess what I really need to know now is - what is the best way for me to level the floor?

** If I use a sand cement screed - what strength is recommended and is it possible to taper it to the high point as the floor gradually drops from the centre to the outer wall. For example close to the centre of the room it is only 10mm out, but as you move closer to the wall it falls, to 20mm than 30mm and than to 40mm.

** If I were to attempt to use a leveller again - what is the best product to prime the existing concrete.

I am at a loss as to what to do as I don't want it cracking off again.

Once again, thanks for any help.

Diana

 

[Leatherface]

Chaps

My first advice to ALL - is search forums using keywords for advice on any subject - it is all there.
In this modern day and age there is no need to use chippings with self leveller - there are products out there that will self level from 30mm, 40mm and 50mm in one go without chippings. Use the manufacturers recommended primer.

When embarking on a new project you are unsure about then always phone the technical helpline of the manufacturer.

 

[Rosco0110]

Take look at this it should help you. Saves me writing a big speel. I used one on a guys garage floor, his was all over the shop .
www.irishcement.ie/download/Floor%20Screeds.pdf

 

[kandd]

Thank you so much for that link Rosco. :hurray:


I am off to do my prep tomorrow. Hopefully I will be tiling in the not too distant future without any further dramas.

Diana