From the moment Hadleigh Parkes crossed after just 61 seconds to the last of Gareth Anscombe's six penalties, Ireland were taken apart by a much superior team at the Principality Stadium and needed a last-play try from Jordan Larmour to avoid being shutout.
Gatland - who became the first coach to achieve three Grand Slams in Five or Six Nations history - refused to take any the pats on the back for the success.
The roof of the Millennium Stadium will be open during the crucial Six Nations clash between Wales and Ireland in Cardiff on Saturday.
In truth, once Parkes gathered Anscombe's chip over the top and dived in for the opening score, there was no coming back from that for Ireland.More news: Iranian human rights lawyer sentenced to 38 years in prison, 148 lashes
Wales have now claimed four Grand Slams in 15 seasons - 2005, 2008, 2012 and 2019 - and they will head to the World Cup six months from now as major title contenders.
This comes after Ireland coach Joe Schmidt accused Wales of breaking tournament protocol by circumventing his side in the discussions whether the roof should be open or closed.
"Look, it is a very competitive Six Nations", said the 36-year-old grizzled hooker.
Despite a weather forecast for Cardiff on Saturday of strong winds and torrential rain, Ireland have requested that the roof remain open.More news: Jurgen Klopp predicts Reds won't spend big this summer
Wales' forwards laid the foundations, driving forcefully from a lineout, but the try owed everything to Anscombe, whose sublime angled kick off the outside off his right boot was caught by Parkes.
Wales were then forced into a major reshuffle when wing George North was forced off injured.
It should have arguably been more just three minutes later, but Wales saw a penalty award reversed following a challenge by scrum-half Gareth Davies on Ireland centre Bundee Aki.
"I am proud of the players it is not about me it is about the players they were playing for themselves their families and Wales", said Gatland.More news: Video shows Chelsea Clinton berated for her 'rhetoric' for causing mosque shootings
Asked about the roof situation, Wales captain Alun Wyn Jones said: "We know, as players, that it's going to be open. They've had so many days in the team when they've been the hub upon which the wheel has turned and the wheel has generally gone forward".
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