David Stutzman
Accessibility standard ANSI A117.1 requires exposed water supply and drain pipes to be insulated or configured to prevent contact. Here is a lavatory installation photographed in a Philadelphia, PA restaurant. The only insulation is installed on the angle shut-off valve for the hot water. Yes, the rough-in was reversed (hot on the right) and the flexible connections crossed behind the drain pipe.
No insulation is provided on the drain line nor the cold supply line. ANSI A117.1 makes no distinction between hot and cold supply lines. Water supply lines are supposed to be insulated.
There are a number of products on the market that will allow lavatories with exposed piping to comply with ANSI A117.1. Here is one example from IPS Corporation, the Truebro® LAV GUARD® 2 showing a correct installation.
Be sure to include escutcheons with the plumbing specifications to ensure the gaps between the wall finish and piping penetrations are concealed, unlike the photo shows.