just wondering how should water proofing be done? during my place renovation, they sapu the floor and wall (up to 1 feet high) with the black tar thingy..
now got water seeping and water marks already.

but i think the possible reason could be due to they use cement as grouting instead of proper grout powder..their reason was use white grout will turn yellow later..so use cement wont obvious (i found grey coloured grout later so i now i know they lied).

what are the remediation can i do now? regrouting without replacing tiles will work?