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Discussion Starter #1
We bought a rehab project, it had foundation damage that was hidden by the "flipper". Instead of raising the foundation and the slab, they cut the slab out of the cracked floor and repoured it sloped to match the sunken foundation.

I had the foundation raised and piers put in. But now there is a sag in the slab that needs to be filled. The deepest part is 1-3/4 low but most of the area, about 300 sq/ft is from 0" to 3/4".
I was thinking about deck mudding the deep parts to save on cost. But I'm not sure how to transition to a material that will feather edge. To do it all with SLC would be pretty costly. Also, the door in the laundry room will be about 1/2" lower than "level" so I don't know how much slope I can stand without it being too noticeable. I raised the wall that the door is in and grouted under it but I really couldn't get it that last 1/2".

Also, can I do deck mudding in smaller areas and have them all bond together?
 

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You can use the material you want by just following how regular concrete is poured which is to use boards and such to contain the mix. Cut your "board" to the height you want or scribing and such and pour. Leave just enough so you can switch to a material that you can feather. I used henry masonry patch to fill about 1" depth, half inch at a time, and feather. Self leveling, you can't feather since it is more or less a liquid. Feathering is not the same as feathering with joint compound, example. Joint compound is finer material. But whatever finish flooring you use, it will bridge it.
 

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If you use the portland+sand-based "deck mud" I think you can only spread to a 1/2" or 3/4" edge. I know there is a product that can be feathered from like 1 1/2", brand slips my mind (too many "-crete" names), but may not be available at big box stores. I don't see why you can't put a gypsum-based self leveler on top of the deck mud if you follow the priming directions. The deck mud will be porous so you'll still use a bit of the leveler. It definitely matters what the use of the area and what you are putting on top of it though.
 

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Discussion Starter #4
I'm going to ceramic tile the area after it is leveled. But I'm going to need to do the leveling in stages, I don't have help and it's a lot of sq/ft with obstacles.
The area that is deep, 1" to 1-3/4" isn't hat big maybe 50 sq/ft. But it is a laundry room and into the kitchen. My plan was to do the laundry first, it is the deepest area. I can put a board in the doorway to make an edge. My plan was to deck mud the low spot, then top coat to fill to the final grade and out to the edges. How long should the deck mud cure before I top it?
 

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But now there is a sag in the slab that needs to be filled. The deepest part is 1-3/4 low but most of the area, about 300 sq/ft is from 0" to 3/4".
Ayuh,.... Do you know for a fact that it's done settlin',..??
Are you Sure there's no more dead space under the slab,..??

I'd sooner think pumpin' sand, or concrete, or even foam under the slab to raise it would be better in the long run,......
 

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Discussion Starter #6
Ayuh,.... Do you know for a fact that it's done settlin',..??
Are you Sure there's no more dead space under the slab,..??

I'd sooner think pumpin' sand, or concrete, or even foam under the slab to raise it would be better in the long run,......
That has all been done. The floor was jacked with foam when the walls were lifted. But since the company doing the work to flip the house before we bought it cut the floor out and poured it crooked with tons of rebar, we can't get it back to level without breaking it to pieces. We did all this about a year and a half ago. It has not moved since.
 

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Discussion Starter #7
We repaired all the drywall and stucco and it hasn't re cracked, so we should be ok. Though here, in this soil, it is always a gamble.
 

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I forgot to add that my problem was dipping wood floor and most of the advices was against using cementious material to fix the wood frame, wood finished floor. And I fixed most of it using wood panels and tarpaper to fill but there was one spot (no more than 3x5') that I couldn't figure out.
This spot was dipping from 1/2" to about 1 1/4". The patch compound was expensive and not recommended for direct pour on wood floor. So I screwed on 1/2" wonderboard first then topped with the patch compound.
As such, you can use concrete board, wonderboard, metal lathe, whatever available, to fill the dip. Example, if your deck filler can't be thinner than 1/2", set up a screed board to contain and fill to 1/2". Then it may be cheaper to make up some of the dip with 1/4" masonary boards.
BTW, study your floor and compromise the flat level surface for what you really need. Even 1/2" dip in 8' would be ok with me depending on traffic pattern and what would be noticed vs practical.
 

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With a laser level you can map out the floor to find the line where it is within 1/2".

On that line you stick down self sticking weather stripping to use as a dam and border for the rough concrete filler. In the deeper areas you pin a few nail so the heads are 1/8 to 1/4" low for a depth marker , use a primer and pour concrete. Then remove the weather stripping and do your SLC over all of it.
 

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Re: filling a sag in a slab.

cement-all has a good mtl for filling birdbaths such as you describe,,, find it in the apron/vest stores,,, ALSO buy their retarder & USE IT !
pay attn to prep - most jobs fail due to improper methods
 

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Discussion Starter #12
With a laser level you can map out the floor to find the line where it is within 1/2".

On that line you stick down self sticking weather stripping to use as a dam and border for the rough concrete filler. In the deeper areas you pin a few nail so the heads are 1/8 to 1/4" low for a depth marker , use a primer and pour concrete. Then remove the weather stripping and do your SLC over all of it.
How long does the concrete need to cure before top coating?
 
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