Mark O'Prey had travelled into Glasgow on Friday from his flat in East Kilbride to see his favourite local band Esperanza perform at the Clutha Vaults.
His sister Louise O'Prey said the 44-year-old was unlucky because they believe he was killed by timber from the roof while he was trying to rescue others.
Speaking from the family's converted farmhouse near Cambuslang, mum-of-four Louise said she thought Mark - a 6ft 3in judo champion - had dived further into the wreckage to help get people out.
She said: "Mark wasn't hit by the helicopter. We think he was hit by a joist from the roof.
"He's got a few marks on his face, but he's got no damage to his body whatsoever.
"He's just been really, really unlucky. He was standing where the band was, which is not where the helicopter came down.
"We thought maybe the reason he didn't make it out was that he went to help someone else, because that's just Mark in a nutshell."
Louise said the family, including mum Mona, 71, dad Ian, 67, and sister Barbara Todd, 38, who were all at the Cambuslang house, have some comfort in knowing that Mark did not suffer.
She said: "My mum's been haunted by the talk that there were voices heard on the Saturday morning.
"Was that maybe Mark? Did he try to get out? But we know from the post mortem that he died straight away and didn't suffer."
Louise described window cleaner Mark, who is dad to 15-year-old Liam, as a music lover, who regularly went to see Esperanza play live.
She said: "He absolutely lived for his music. The band don't normally play in the Clutha Vaults, so he was going there to see them. "
She said that while on a night out two weeks ago Mark was talking to his aunt about when they die - and Mark said "he would like to go out to good music".
Louise added: "Two weeks ago - and now there he is. He's gone listening to the music he absolutely loved.
"He's a fantastic brother, we loved him so so much. He's an unbelievable character, one in a million.
"Mark was an adorable, lovable giant. He was always laughing and would do anything for anybody."
The family say they are still coming to terms with the tragedy.
As the Evening Times reported, they spoke out on Sunday after becoming frustrated at why they were not being given information on the whereabouts of their loved one. Mark's body lay at the site for two days before it was removed.
Louise said: "It was so frustrating trying to get information, but once we managed to speak to people on Monday lunchtime we got the answers.
"But it wasn't handled well at all."
The family was told on Monday the rescue operation was difficult because giant bits of stone kept falling down and there were fears that if they pulled a wall down then casualties would be crushed.
Louise said: "They told us that it was only when they brought that helicopter out that they knew there was three floors.
"With hindsight now, we can see the difficulties but we didn't feel we were getting the information."
Louise said she hoped lessons would be learned from the tragic crash.
She said: "I've said to the officers if there's ever a learning curve, it needs to be that the chief people speak to the families.
"When it goes through six or 10 people you can't get the right information.
"There were only nine families that they had to feed information to. Why could they not come and speak to us?"
Despite this the family wanted to praise the emergency services and everyone else who helped out, including the staff at the Holiday Inn Express who assisted the relatives of crash victims and survivors.
Louise said: "On the Sunday we went early and I thought I'd like to sit in the hotel. It was just so comforting to be there beside Mark, and we could see what they were doing across the road. Everyone has been supportive of us."
Mark's funeral will take place on Monday(Dec 9) at St Bride's Church in East Kilbride. The family have asked that mourners reflect Mark's vibrant personality and do not wear black.
His mum Mona said: "He's a lovely boy, he's my first born. We'll miss him so much."