Police have urged people to check vacant homes, sheds and cars in the search for Noah Donohoe.
The teenager, 14, went missing on Sunday evening and officers believe he may have fallen from his bicycle in north Belfast and injured his head.
There are reports he was later seen on the bike without his clothing.
PSNI Superintendent Muir Clark asked people to check their washing lines for missing items.
He said: “We are working on the hypothesis at the minute that Noah may have suffered some injury causing him to behave in a way that is not normal.
“He may be seeking either shelter because he has no clothing or money, or he may not realise where he is.
“That is why it is so important for members of the public to check their properties and cars.”
Officers have recovered his bicycle, helmet, trainers and mobile phone, and have been searching a densely wooded area which he was reportedly heading towards.
He was last seen in areas close to the Shore Road.
Mr Clark said: “This behaviour is completely outside Noah’s character.”
He added: “I need to know that all the outbuildings, all the places Noah could take refuge in, have been checked.”
There has been a massive community response, with hundreds of volunteers coming forward to help search for Noah.
His mother Fiona said she had been overwhelmed by all the support.
“It is actually giving me and my family the strength to fight for him to be found,” she said
“I just wish at this stage people would start offering for their houses to be searched so that shelter could be eliminated.”
She added her heart was broken.
“I am begging people do this,” she continued. “I know I am asking a massive thing but if you knew my Noah, he was the most thoughtful, loving darling who does not deserve to be suffering or unfound.
“Please hear my plea, I am speaking for Noah – my baby.”