Backs Jonathan Davies and Alex Cuthbert scored the tries in a 26-9 victory, but the pack built an imposing platform.
"Our scrum was outstanding," said Roberts, after Wales weathered torrential rain to post four successive Six Nations away wins for the first time. "Adam (Jones) was magnificent, as were Gethin (Jenkins) and 'Hibbs' (Richard Hibbard).
"I take my hat off to the forwards – they worked so hard.
"Defensively we were strong as well. The communication was good.
"We've been doing a lot of hard work with (defence coach) Shaun Edwards, and not to concede a try away to Italy is an achievement."
Wales next head to Murrayfield on March 9 to meet Scotland.