The additions of free agents Shaun Higgins and Jarrad Waite did not "squeeze out" North Melbourne midfielder Levi Greenwood, according to the club's football boss Geoff Walsh.

PRESS PLAY above to listen to the Geoff Walsh interview

After signing Higgins and Waite last week as the free agency window opened, the Roos' buoyant mood was offset by the likely departure of Greenwood to Collingwood.

Greenwood informed the club on Tuesday of his intention to join the Magpies, on what is understood to be a four-year deal worth up to $1.8 million.

But Walsh said the arrivals of Higgins and Waite had not meant there was a lack of salary cap space to keep Greenwood.  

"At the end of the day, despite what some people may think, your TPP (total player payments) and salary cap projections aren't done on the back of a scrap bit of paper the night before trade week starts," Walsh told NAB AFL Trade Radio.

"These are projections that are done 12-24 months out. No one's been squeezed out because of the people who have arrived at North Melbourne.

"The commerciality of the AFL world says that players out of contract have the opportunity to field offers.

"The currency that Levi was provided by his form this year says that there were a number of clubs interested in him, and the demand for his services were such that he was able to take an offer at the top of the tree."

Walsh said the Roos and Collingwood had started discussions over a deal to send Greenwood to the Pies, but that he didn't expect negotiations to drag on.  

"We've only had a brief chat with the Pies," Walsh said.

"Obviously the fact they consider he's going to be a strong part of their midfield by the offer suggests I don't think it will be taking a hell of a lot of time to do this deal.

"They've indicated how strong how they want him. We certainly expect them to come back with something that's fair and reasonable to ourselves and themselves."

"I think it may rely on a few other things they have in the melting pot to see where it actually ends up."

Out-of-contract North midfielder Liam Anthony had attracted some interest from clubs on the opening day of trades, Walsh added.