The true number of people homeless in Ireland is likely double or treble the official figure, according to Peter McVerry.
On Friday, the Department of Housing announced 11,632 people were living in emergency accommodation over Christmas - yet another record total.
The figure from the Department of Housing includes 3,442 children who are growing up in B&Bs, hotels, and other state-provided temporary accommodations.
The figure from the state does not include hidden homeless, rough sleepers, women in refuge centres, refugees, or asylum seekers.
"We have record numbers of people who are homeless who are registered, but there are a huge number - thousands - of homeless people who are not registered.
"People who are not registered include people sleeping rough, women and children in domestic refugees who cannot return home [and] at least 5,000 asylum seekers who have been given permission to stay in Ireland [and] can't leave the Direct Provision places.
"Probably the number of homeless people is double or treble the 11,600 that we have at the moment".
Peter McVerry said modular homes should play a bigger role.
"I think we need to increase our use of modular homes," he said.
The Government has bought 700 modular homes, [but] they could buy 7,000 modular homes.
"We need to bring back into use all the empty buildings that we see on every street in every town in the country.
"The Government needs to meet its own targets for housing, for social housing," he added.