What underlay does my condo need?

Whatever your corporation's current rules specify, which is not something a supplier can tell you and not something the Building Code answers. Ontario Building Code Section 5.8 sets sound requirements in terms of sound transmission class and apparent sound transmission class and contains no impact insulation requirement at all, so any impact number you have been given comes from the condo rules. Two things follow. The requirement applies to the whole floor assembly rather than to the underlay alone, so an attached pad on a laminate plank often does not satisfy it. And acoustic underlay is a real cost, roughly $0.80 to $3.50 per square foot depending on the performance required.