The presenter of DIY SOS said their latest project will "go from a shell to family home in nine days".
The team from the BBC One programme is in Corby, Northamptonshire, to rebuild Jackie and Colin Hutchison's house for their last "big build" of the year.
They used a £60,000 loan to modify the home for their 16-year-old son Jordan, who has cerebral palsy and epilepsy.
But their builders let them down about a year ago and Mr Hutchison said they were left with "a complete mess".
"We needed a toilet that works for him, a wet room and hand rails," said Mrs Hutchison.
"Jordan loves pool, so we are going to have a pool table hopefully. That was our plan."
But what the family were left with was a shell without a roof, and the couple and their three children moved into Mrs Hutchison's mother's house.
She said: "This whole thing has been going on for months and months.
"We just want to come home."
The DIY SOS team began work on Tuesday with the help of volunteers and tradespeople.
Presenter Nick Knowles said: "To have a youngster with a disability and not be able to go into an environment to try make life better is really frustrating."
He said that with more than 100 people working on the house "you get this extraordinary sense of well-being and everybody helping each other out".
"We are going from a shell to family home in nine days," he added.
Mrs Hutchison said a completed house would have a dramatic effect on their lives.
"It would mean the world, especially to Jordan and for us as parents to watch him grow into a young man and just have that little bit of independence," she said.
The DIY SOS programme showing the build will air later this year.