How old is the slab? Moisture and mold remediation are expensive and extensive. Both require ++ effort.

The AGE of the slab will tell us the chances of a moisture barrier underneath the slab. Regardless, of a moisture barrier, you need a dry concrete.

The Drylok (out of Belgium...so we know it is GOOD...the country is technically underwater...so they know something about moisture mitigation) is for the WATER mitigation moving up through the slab.

Once that is finished you will STILL HAVE mold/fungi spores in the AIR...once the spores settle back down to the floor, you need something that KILLS THEM once they land.

The fungicide OVER the Drylok is to kill the REMAINING mold spores that are floating in the air. You do NOT want the mold to reestablish a colony. You are paying +++ $$$ for mold removal. It would not make sense to give the mold spores another chance at life.

This is like giving a patient antibiotics AFTER an operation. You do it as a PREVENTATIVE measure. You do it to ensure you do NOT have a problem with infection after the work has been completed.

Thank you! That explains a lot and is very helpful. The house was built in 1976, so the slab would be 34 yo. There is no drain yet, the concrete does get fluorescence every time it rains or snow melts, so I suppose we need to immediately plan fo putting the drain inside the perimeter to prevent dry lock fro peeling?

A slab from 76 is 44 years old (I was born in '71 and am 48 years old for the next 3 months). I can guarantee you do NOT have a barrier of any kind underneath. That is the basis for 80-90% of your issues.

Concrete is a rigid sponge. It LOVES to grab water and hold on to it. That water evaporates UP into the air of the home (damp warm air = mold incubator). The WATER evaporates but the ground salts are left behind. That's what produces efflorescence (white powder stuff sitting on the concrete).

The concrete needs to be scarified (shot blasted) and then coated with a vapour barrier (roll on or spray on x 2 coats) then a primer and then retopped with new concrete. Now you can have any floor you want in your basement.