Hayden last spoke to his mother Jacqui from an unknown person's cellphone in the Linwood area before going to a friend's house on Cashel St on August 22.
That was the last time anyone has seen or heard of him.
Detective Senior Sergeant Tony Hill said today that the SAR phase was part of the ongoing enquiry to determine what happened in and around the location August 22.
"This is a further step in building a picture of events on that day and the days after,'' he says. "We will be looking for evidence, such as clothing or other items that may have been discarded, and aiming to narrow down the possibilities of what has happened to Hayden.
"There are a number of unoccupied addresses in the vicinity and these will be a focus for the search phase.''
Mr Hill said the forensic examination at the Cashel Street property was continuing today and could continue for a further two days.
"The size of the property and the multiple dwellings on the site have made this a slower process than initially anticipated.
"The investigation team is also continuing to speak to various people who have come forward during the enquiry. We are making good progress in establishing the events surrounding Hayden's disappearance.''
