[calderp]

I'm working on a house where three nearly-finished rooms need work to level the slab in order to lay tile. The existing slab is structurally sound and in good condition but it has high and low spots, and a couple of seams between different pours. It is also 2" lower than the rest of the house. The goal is to level the slab, while raising it 2" to even out all the floors in the house. Total volume for three rooms (14'x10' average) is approx. 80 cubic feet.

I could use advice on a few points:

1. What is the proper concrete product to use? I understand that you can't pour concrete for a structural slab of less than around 4" thick, but as the slab underneath is in fine shape, would regular slab cement be acceptable for this use? How difficult is it to get a level pour with standard slab cement on an uneven surface?

2. If it is necessary to use 'leveling mix' or some kind of self-leveling product, are there any issues with doing a 2" pour? The products I'm familiar with seem to expect you're pouring no more than 1/2".

3. How important is it to clean the old concrete? There is residue from carpet glue there. Since we're pouring 2"of new concrete, can we just scuff it up and clean up whatever comes up easily, or is it important to have a very clean surface?

3. Is there another, better way to do this than trying to pour the whole area at once? Laying out a grid with lumber and pouring in sections, something like that? Or would that introduce issues down the line with the integrity of the tile on top?

Any advice would be great here, concrete is not really my forte.

Incidentally, this is not a true contract job, I'm working for a close friend. Normally, I wouldn't be trying to learn a new skill in someone else's house!

 

[brunothedog]

mortar screed is the old way, and least expensive.

there are different methods, i like this system

 

[calderp]

Thanks, that screed is interesting stuff, I wasn't familiar with it. The problem I see is the curing time. From what I read a 2" layer of screed would take close to two months before it was cured enough to lay tile.

An alternative seems to be buying a 'quick-cure' version, like Mapei Topcem Pronto, but then the cost of materials is much higher than concrete. So unless I'm missing something here, I'm not sure screed would work well for this project.

 

[cdkyle]

My suggestion would be to have your friend call a contractor or professional from your area that would have the expertise to handle a project like that. Good luck.

 

[brunothedog]

Thanks, that screed is interesting stuff, I wasn't familiar with it. The problem I see is the curing time. From what I read a 2" layer of screed would take close to two months before it was cured enough to lay tile.

An alternative seems to be buying a 'quick-cure' version, like Mapei Topcem Pronto, but then the cost of materials is much higher than concrete. So unless I'm missing something here, I'm not sure screed would work well for this project.

3 days i think with additives