Almost 1,000 properties owned by the Housing Executive are lying vacant - some for years on end - despite families left waiting for homes.
More than 16,000 people are homeless in Northern Ireland. The Housing Executive has 37,611 households on its waiting list - 23,694 are deemed to be in housing stress or priority need.
The average wait for a home is around 38 months - just over three years.
Despite this acute need, the Belfast Telegraph can reveal that the Housing Executive is in possession of 926 vacant properties.
Shockingly, these have remained vacant for a combined 1,677 years - an average of nearly two years per property.
Campaigners have urged the Housing Executive to act quickly to bring the properties back into use.
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Jim Dennison, who is chief executive of the Simon Community NI, said: "We are in the midst of a homelessness crisis and the figures are on the rise.
"Without doubt, bringing 1,000 empty properties back into use would end homelessness for many people and families."
The Housing Executive said less than 1% of its stock is vacant - and it compares better than most other UK social housing landlords.
An investigation reveals:
The Housing Executive defines actionable properties as those which are "vacant while in the process of being allocated or are awaiting change of tenancy repairs."
These can include properties which are in an area considered "difficult to let" or where the type or condition of the property affects the ability to allocate.
Non-actionable voids are properties not available for allocation as they are being held vacant for operational reasons.
This can include being used to house a tenant on a temporary basis, pending works to their home.
It also includes properties which have been identified for sale or transfer or have been approved to be demolished.
Figures released under the Freedom of Information act reveal the spread of vacant homes across Northern Ireland:
Tony McQuillan from homeless charity Shelter NI said the lack of a functioning Executive was harming the ability of organisations such as the Housing Executive to help those in need.
"It's an incredibly long period of time for properties to be vacant - nearly two years per property," he said. "I would hope that there is some kind of strategy being employed by the Executive to find a solution to letting these properties."
The Housing Executive said the median waiting time - in other words the midway point - was a more accurate indicator of waiting times than the mean.
It said the median wait is "less likely to be skewed by significant outliers".
The median average waiting time across Northern Ireland was 22 months.
A spokesperson said the Housing Executive manages 85,866 homes in Northern Ireland.
He said: "The Housing Executive's lettable voids are among the lowest in the UK.
"When benchmarked against other social housing landlords in the UK (who manage stock of over 20,000), the Housing Executive is the third best performing in terms of its numbers of lettable voids.
"Our lettable voids are at their lowest ever level, with only 0.28% of our current stock vacant."