And the home side's start was shaky with fullback Nick Harding leaving the field in the second minute after injuring himself in the warm-up.
In contrast, Ruapehu looked good and had a firm grip on the run of play when halfback Karl Ellers-Green charged over after a period where his side had Border pinned on their own line.
It was good reward for Ruapehu who had been aggressive in forcing Border into errors.
But that was about as good as it got for the northern club.
Minutes later Border reserve back Grayson Tihema, who had just come on for Harding, latched onto a kick through to open Border's account with a try in their first real opportunity.
Prop Lance Devane muscled over ten minutes later, rewarding his side for turning down a shot at goal and at the 30th minute, winger Tom Symes coasted through Ruapehu's defences to almost put an end to the visitor's chances.
But Border would have to wait another 35 minutes to seal their place in next week's final against PGG Wrightson/Ballance Taihape.
With the score 17-5 at halftime, Ruapehu hung in, frustrating Border in the opening of the second spell and edging closer with a Craig Clare penalty.
But Border's ability to absorb pressure then pounce showed through again and with 15 minutes to go their backs cut loose from halfway - ending in Tihema flicking the ball on as he was falling into the corner flag for winger Isaiah Hooper dive on and score.
The match was won from that point but Border scored two more tries in the next five minutes, with No8 Ranato Tikoisolomone breaking clear to put flanker Kieran Hussey away, before lock Gavin Thornbury stretched the lead with Border's sixth try.
Front rower Gabriel Hakaraia pulled back a deserved try for Ruapehu in the dying stages.
For Border assistant coach Paul Mitchell, the game had gone much as planned. "We always knew that they play their best rugby in the first ten minutes and that's always how it was going to be and then after than we sort of dominated them for rest of the half," he said.
"The key to today was just weathering the storm in that first ten minutes and then we knew they'd run out of steam after that.
"They've had five hard weeks of having to win every week and we knew they were battered and bruised."
Mitchell was also happy with his side's risk versus reward approach.
"I think we're always going to have those dropped passes because we're pushing the envelope a bit trying to play an expansive game but, yeah, we'll be looking to fix that up," he said.
"We're just going to keep working on what we've been working on - carrying strong around the rucks and then our backs will hopefully score the tries.
"Taihape are a great team and they're well coached. We definitely know we're in for a big battle when we meet them."
Ruapehu player/coach Andrew Evans said his side had made too many mistakes to really test Border.
"Border were clearly the better team on the day so they deserved the win today. We just probably made too many mistakes and they capitalised on it.
"We just lost the ball too much I think and probably didn't take the right options and just not being urgent enough."
Waverley Harvesting Border 34 (Grayson Tihema, Lance Devane, Tom Symes, Isaiah Hooper, Kieran Hussey, Gavin Thorburn tries; Lindsay Horrocks con, Jamie Forsythe con) bt McCarthy's Transport Ruapehu 15 (Gabe Hakaraia, Pahl Elers-Green tries; Craig Clare pen, con). HT: 17-5.
