The Peter McVerry Trust is announcing the first phase of a series of social housing projects for Dublin.
It has secured planning permission for 18 apartments in Townsend Street - its biggest project to date.
Separately, in Finglas, the charity will be building six social housing units for homeless people with complex needs.
The trust's CEO Pat Doyle says residents will benefit from both on-site and visiting staff supports.
"For example, we have a homeless man who's blind, in our services, who needs support, so this would be more like six units in a little cluster, and our staff would be able to support people to leave homelessness and move into their own permanent bungalows," he said.
"So we're delighted. Two social housing projects, one for 18 units worth €1.7m and the second six purposely-build units worth €1.2m."