On Tuesday night people gathered at Croydon Rugby Club to search for the schoolgirl who has not been seen since leaving grandmother Christine Sharp's home in New Addington, southeast London.
Club secretary Sue Randall said: "Everybody wants to help, we're just pulling together to try and find her."
She said people had searched the area throughout Tuesday evening with some asking for torches so they could continue through the night.
More searches are expected to take place throughout today.
Earlier police searched a local wood, Birchwood, less than a mile from Tia's grandmother's house in The Lindens.
Tia's stepfather David Niles said the family were "in bits", adding: "I just want to find my little girl."
Mr Niles, wearing a Find Tia campaign T-shirt, said: "How would you feel if it was your daughter? We're in bits. The whole country has helped us and is supporting us."
Scotland Yard has said the search was "very much ongoing", including physical searches and other work to try to track down the 12-year-old who went missing on Friday afternoon.
The Sun newspaper has offered a £25,000 reward for information that will lead to police finding Tia.
It was believed the last person to see her was Mrs Sharp's partner, Stuart Hazell.
But Mr Niles said he was unsure about that, adding: "The last time I saw her was on Thursday morning before going to work (at the family home in Mitcham).
"When she left the house she shouted 'Bye' and 'See you by six'. She always takes her phone but it was dead."
Mrs Sharp, speaking from her terraced home, said she hoped an image of her granddaughter taken outside the nearby Co-op on Thursday would jog people's memories and bring forward new information.
"We're hoping the pictures will jog someone's memory, yes," she said.
Outside the house a solitary candle burned in a glass holder with a plastic bottle covering it.
Tia vanished after telling relatives she was going to the Whitgift Centre in Croydon town centre.
Police have been scouring hours of CCTV footage but said they had not found any trace of the schoolgirl, who has never gone missing before.
Hundreds of "missing" posters have been distributed around New Addington and Tia's face looks out from most local shops and noticeboards.
At a bus stop close to her grandmother's house in The Lindens, well-wishers have left dozens of burning candles and tealights with hand-written signs asking for Tia to be brought home.