How To Level A Sloped, Uneven Concrete Floor - Cabin DIY

Leveling a concrete floor is relatively straight forward. There are several readily available floor leveling compounds that are easy to apply and use. They are also expensive and are limited in the amount of correction they can provide, generally only recommended for use of 1″ or less.

Knowing how expensive self-leveling floor products are and realizing I needed 3 inches of material in some areas, I needed consider a flour leveling solution that was economically reasonable and one that could fill in the deeper deficits I had.

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The idea I came up with was to use both conventional concrete mix (and motor mix) as a base layer, to get the floor close to level and finished with the more expensive self-leveling underlayment mix.

It is true that some of the self-leveling floor mixes can be used by themselves to level floors with an inch or more out of level, but these products are typically five to ten times the cost of traditional concrete products, making them cost prohibitive for me to use for the entire project.

The plan is to remove the old carpet, level the floor and resurface the floor with rustic tile. We were starting with very old carpet glued to a very out of level concrete slab. Removing the carpet was fairly straight forward, it was several decades old and came up very easily. Unfortunately, the carpet glue residue left on the concrete slab was not so easy to remove.

After hours of scraping at the stuck carpet glue residue, I figured there must be an easier way, and headed to the rental center at the local Home Depot. I rented a Clarke FM series commercial floor polisher. Using the brush attachment, I was able to remove most of the remaining glue residue in about 30 minutes.

Finally down to the bare slab, I was ready to get started leveling the concrete slab floor. If you look closely alone the inside wall and you will appreciate just how sloped the floor is — nearly 3″ low half way across this 12′ span! Prior to leveling the slab, you should check to be sure any structural / support issues are addressed prior to leveling the floor. Additionally, ensure that the floor to be leveled can handle the weight of the material to be added for the leveling process.

So to get started, I used premixed bags of high strength Portland cement mix (fortified and fiber reinforced) for the first layer and to fill in most of the deficits.  To feather the edges of the coarse rock aggregate, I used a sand mortar mix fortified with latex. The final leveling layer used the more expensive self-leveling underlayment mix.

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The results were fantastic. The less expensive concrete worked well to fill in the the majority of the low spots and allowed me to use much less of the more expensive self-leveling underlayment mix. I saved well over a thousand dollars by using this multiple material in layers technique. The trade off was time. The concrete needed 3 – 4 weeks to cure prior to applying the floor leveler, requiring over a month to complete the entire process.

Here are some photos of the initial carpet remove and slab preparation for leveling.

After the floor polisher did its job and freed up the old carpet glue residue, I just vacuumed up the residue. I did need to do a bit of hand removal work close to the walls and in the corners that the floor polisher could get to.