Ruthless Wales sealed a record third Grand Slam under departing head coach Warren Gatland with an emphatic 25-7 victory over lacklustre Ireland at a raucous Principality Stadium.

Clinical Wales rose to the occasion with the roof open and rain lashing down in Cardiff on Saturday to end a six-year wait for a Six Nations title and claim a first clean sweep since 2012.

Hadleigh Parkes set the tone with an early try that was set up by the excellent Gareth Anscombe, who was on target with three penalties to give Wales a 16-0 half-time advantage.

Indisciplined Ireland were a shadow of the team that pulled off a Grand Slam last year and Wales took full advantage, Anscombe adding another three penalties in the second half in a perfect kicking display to take his tally to 20 points.

Nothing went right for disjointed Ireland as they relinquished their title with a whimper, Gatland - who will end his long reign after the World Cup - becoming the first coach to mastermind three Grand Slams in the tournament.

Ireland - who scored a late consolation through Jordan Larmour - finish third behind England in their final Six Nations with Joe Schmidt in charge, while magnificent Wales' winning run now stands at 14 matches after they got the job done in emphatic fashion.

Wales eased the nerves by making a dream start, all-action centre Parkes plucking Anscombe's deft kick over the top to score inside two minutes.

George North made an early exit with a wrist injury and Alun Wyn Jones had treatment on his knee, but a long-range penalty from Anscombe - shifted to full-back with Dan Biggar on at fly-half and Liam Williams moving to the wing - extended the lead.

Ireland applied some pressure but a rock-solid Wales defence kept them scoreless and Anscombe punished indiscipline from the defending champions with two penalties to put Gatland's men 16-0 up at the break.

Composed Wales carried on where they left off after the interval, Anscombe again making no mistake again from the tee after Cian Healy was deemed to have come from the side of a maul.

Ireland continued to struggle in tricky conditions, summed up when Johnny Sexton threw a pass straight into touch in a promising situation after the holders were finally able to put phases together.

There was no let-up from relentless Wales - led by the immense Jones - and two more Anscombe strikes put them well out of sight.

Ireland finally breached the Wales defence when Larmour stepped outside to score after the ball was moved swiftly from left to right and Jack Carty added the extras, but the party had already got under way by then.