The Simon Communities says the number of people it helped over a two-year period has risen to over 13,000.
The homeless charity's annual report shows there's been a two-thirds increase in demand for its services between 2015 and 2017.
It also says 2018 is set to be a record year - with over 3,000 families going to it for help up to June.
Spokesperson Niamh Randall says the crisis can be solved - but the government's policies need to change:
"There are solutions and it is about making the correct political decisions and we should never accept that homelessness is normal.
We should never accept that living with such fear and uncertainty and trauma and difficulty is normal.
“The numbers have increased year on year, but 2018 looks like it’s going to be a record year in terms of people accessing our services, which is a huge disappointment, that's not where we want to be, we want to see numbers reducing, we want to see more people moving into their homes.
“What we saw from January to June 2018 was an increase in people accessing our emergency accommodation services - 1,200 people, that was less than 1,000 people for the whole of 2017, we also saw 3,140 families, that figure was 2,006 for the whole of 2017.
“We are anticipating that 2018 will be a record year, unfortunately.”