adhesiveconcretefloorflooring
I removed vinyl flooring that was glued down (by a previous owner) in the 1990's, and there is a significant amount of dried glue left behind on the concrete floor.
The self-leveler and glue that I will be using for the new flooring has different floor preparation requirements depending on whether the old glue is water-based or oil-based. How do I figure out which it is?
The paper backing can be cleaned off with a solvent paint stripper and then wash the old glue off with trisodium phosphate and a scrub brush. Then wash several times with water to remove the residue of both operations. Tile thin set in most cases may not adhere to old glue, especially if you have to use unmodified thin set because you are planning on using an uncoupling membrane like DITRA.
Type of flooring dictates how "perfect" it needs to be, carpet being the least work. Vinyl is flexible so just no real drastic changes.
Below are the basic steps to fixing uneven concrete floors.
Use a straight edge and mark high and low spots. (Really exaggerated case in this image)
Or if you like gadgets, Bosch has a new laser out that lets you easily mark the uneven parts.
You use a grinder (with dust mask and safety goggles) for high spots. You can rent a large floor grinder or get on your hands and knees.
and SLC (self-leveling compound) in low spots. For SLC just follow the manufacturer's instructions. If the floor is really bad you may want to pour the stuff over the whole thing.
Best Answer
Place a wet rag over an area and then put a pot over the rag to keep it from drying out for a day or so and see if the glue softens up. If it does, it was water probably based.