The Residential Tenancies Board is trying to close the loophole that allows landlords evict tenants during renovations.
In new guidelines published today, the RTB says maintenance or repairs aren't enough to make people leave.
Some landlords have been accused of using renovations as an excuse to bring in new tenants at higher rates.
Director Rosalind Carroll is urging anyone with concerns to get in touch.
She said: "W have only had one case referred to us to date, in terms of disputes specifically on the substantial change issue and I suppose that shows that people don't know what they should be doing.
"So what we are trying to do today is say 'look here's what it is, if there is a dispute, please come to us, come to the RTB."