Using thin set to fill low areas by applying it a little thicker (most times it is much thicker) as the tile is being installed, is not a good idea. In fact, most manufacturers indicate in their product literature NOT to use thin set mortar to level or flatten the floor or wall.
You can use thinset to level the floor if its only out a little as you say it is (no more than 1/4"). Thinset will adhere to thinset just fine.
Well, the answer is actually no. Mortars cannot be used to level or patch an existing concrete floor – ever! The materials used in mortars are different from self-leveling concrete and self-leveling cement.
Tile adhesive is generally not recommended for leveling a floor. While it can help bond tiles to a substrate, it does not have the properties needed for effective leveling. Instead, use a self-leveling compound designed specifically for that purpose.
Since thinset is so heavily modified with bonding agents and polymers it has tremendous abilites to bond new concrete to old concrete, however the potential for compatibility issues with other admixtures are a concern. Introduction To Concrete Bonding - Introduction To Concre...
Thinset mortar is an adhesive used for tile installation, adhering these materials to a cementitious substrate. It works on surfaces such as cement, concrete floors, a floor or wall covered in cement backer board, or a waterproof membrane over the top of these materials.
BluCem HB50 has been specifically designed to reinstate reinforced concrete and is therefore ideal for use in such projects. When water is added, the resulting one-component blend forms a lightweight and fast setting repair mortar.
Setcrete Level-Smart can be applied over old adhesive residues, including bitumen, carpet tile tackifiers and ceramic tile adhesives, eliminating the need for mechanical removal, which would normally be required. In such applications, there is no need to prime beforehand, saving further time and expense.
It simply involves applying mortar as normal to the substrate, but then also applying mortar to the back of the tiles. Extra mortar is applied to areas that need it – either areas with dips in, or areas with thinner tiles. This will even out the surface, creating a perfectly flat tiled surface.
Self-levelling concrete is a polymer-modified cement that has high flow characteristics, it's used in the preparation of laying most floor coverings to create a smooth and level surface. Levelling compound can be used on a variety of substrates including concrete, screed, existing tiles, and timber floors.
Using a floor leveling compound to elevate the floor in a specific room and make it match the rest of the house is a low-cost option. This approach is popular among homeowners since it works when applied straight to concrete.
QUIKRETE® Fast-Setting Underlayment and QUIKRETE® Self- Leveling Floor Resurfacer are used for repairing and leveling pitted and rough concrete or wood floors prior to installing carpeting, resilient flooring, or tile.
Use a self-leveling underlayment on low spots on wood. Self-leveler is available in powder and pre-mixed forms and creates a flat, smooth surface in flooring projects. The strength of the product is similar to concrete. Self-leveler dries fast, so you need to work quickly.
Thin-set tile mortar is smooth and slippery and comes pre-mixed or in powder form, which you mix with water. A major advantage of thin-set is that it helps to level slightly uneven surfaces.
Tile set by the thinset method is adhered to the substrate with a thin layer of “thinset” cement. The terms thinset cement, thinset mortar, dryset mortar, and drybond mortar are synonymous. This type of cement is designed to adhere well in a thin layer – typically not greater than 3/16th thick.
Common thin-set mortars shrink as they cure — the displacement of water causes the mortar to retract and pull the tile as it hardens. When this occurs with a thick layer of a common thin-set mortar it can leave an uneven surface from tile to tile known as “lippage,” an unwanted finish result, or crack the tile.
Mortars cannot be used to level or patch a floor – ever! The materials used in mortars render the product unstable once the thickness exceeds the manufacturers' recommended maximum thickness. Most thin-set mortars have a maximum thickness of 1/4" (6 mm) and medium-bed mortars have a maximum of 1/2" (12 mm).
The floor should be mostly level, but don't obsess over perfection. Make Repairs – You may be able to get away with making a few small repairs instead of pouring new underlayment.
Apply the adhesive onto the floor using a notched trowel. Spread it over the area you're trying to level and ensure that it is spread evenly across the surface. While the adhesive is still wet, use a tool with a straight edge or a leveller to ensure that it is smooth and level. Allow for it to dry without interruption.
The Importance of Removing Old Thinset
Adhesion Issues: New thinset may not bond properly to old, hardened thinset. This can compromise the integrity of the tile installation and increase the risk of tiles becoming loose or dislodged over time.
Mistake: Applying too much adhesive can cause tiles to slip or ooze adhesive through the joints. Too little adhesive can lead to weak spots and failed adhesion.
As long as you're following the mixing instructions, have cleared loose material and are applying the new mortar correctly, it should bind with the existing, dried mortar. Refer to the mortar instructions for application details and to see how long the mortar is usable after mixing.
Mortar is not as strong as concrete and typically is not used alone as a building material. Rather, it is the "glue" holding together bricks, concrete blocks, stone, and other masonry materials. Mortar is commonly sold in bags, in a dry pre-mixed form to combine with water.
Conclusion. A skim coat for concrete can breathe new life into old, damaged floors, and with polyurea, you're getting the best possible material for the job. Polyurea offers superior durability, flexibility, and quick curing times, making it the top choice for both residential and commercial spaces.