Hey guys, I know there’s about 100 threads on leveling concrete (I know this because I searched), but I couldn’t find one that really addresses the question I have so here goes. I’ve got a 15×13 room that I’m rennovating which has a concrete floor. I’m looking to lay down flooring over the concrete however I have a leveling issue. The floor is cracked at a peak in about the center of the room that runs most of the length of the room. On each side of the crack the floor is flat but not level. Laying an 8 foot straight edge across the crack I find the floor drops to each side of the crack about 3/4″ at 6 ft.
The issue that cased the crack in the first place has been addressed and the floor is stable. So now what is the best way to level it off. Am I better off using leveling compound which would basically have to be poured across the entire floor to bring everything up to the height of that peak or would it be better to grind the concrete down starting at the peak and working outward? I do plan to lay a subfloor either way so it doesn’t have to be perfect but I do need to get it within tolerances.
Replies
Whoops, little math issue there
Sorry, I was wrong on the amount of drop to each side, should be half of that or about 3/8" at 6 ft.
Grinding
I had a concrete slab ground flat once... it was poured with all sorts of ridges and dips and was going to be tiled, so it needed improvement. I had a concrete cutting company do it... the hourly price seemed quite high ($250/hour?) but it didn't take them long and the thing was hugely improved, with a nice shiny finish. The machine they used was similar to the machines you see them polishing the floors at the bank with, a big walk-behind deal with a garden hose attached. We had to cover the walls with plastic and then do some cleanup afterwards, but it was far easier and better than having the tilesetter try to get SLC in there, as I have rarely seen SLC turn out that flat/level anyway.
I poured a 5x7 bathroom with 1/4" SLC and it came out really nice. I think alot of people forget that you still have to trowel SLC as it is only partially self leveling. For 13x15, do some reading and prep work as it is a 2 person job: One is always mixing a new batch while the other is busy pouring and smoothing flat.
The nice thing is that SLC is VERY soft - like just a little harder that talc when it first cures. If you find something obviously high after it cures you can knock it down yourself pretty easily.