CONCRETE OVERLAYS
When and why should you consider doing a concrete overlay? When areas in the concrete to be finished have been patched, the patches are usually noticeable. For minor repairs such as cracks or limited small areas, an overlay may not be necessary. However, if you've had a perimeter drain and sump pump installed under the floor, where a trench was cut around the perimeter and concrete poured back (see image A), you will need an overlay. This concrete is usually very soft and always looks terrible compared to the rest of the floor. Another example would be when finishing a floor that has had other floor coverings installed. Different flooring materials pose different aesthetic challenges, all of which can easily be corrected with an overlay.
Removing carpet installed with tack strips will leave small divots around the perimeter anywhere the strips were installed from the nails pulling out concrete (refer to image B below). These can be filled and ground down with the floor however they will be noticeable to some extent.
Many people are totally fine with how they look while many people find it undesirable(Refer to image B2)
Tile(all kinds) even once removed and the floor ground down, can leave a permanent tile pattern (image C). This is referred to as "ghosting" and can really happen with anything placed on the concrete either while it was still green/curing, or when left for extended periods of time. Often this condition is secondary to moisture migration. In the case of green/ still curing concrete, objects can cause moisture (critical for concrete curing) to evaporate at different rates. This can leave permanent discolorations. Unfortunately these often times do not become visible until concrete is stained and or sealed.
Glue down floor coverings will often leave trowel notch lines from the adhesive that's absorbed into the surface of the concrete. These can often be removed by grinding as well which means a Grind & Stain or Grind & Seal also an option.
Perimeter drain tile installed via trench and then back filled with concrete.
Nail divots left after removing tack strip from stretched in carpet.
Patched and ground nail holes from carpet tack strip
Ghosting can be seen from previously installed tile.