East Riding Council’s Western Area Planning Committee refused plans from the St Paul family, of Westfield Rise, for the home to help their son Jack adjust to living independently.
Angie St Paul told councillors the single storey home in their back garden was the best option as their son’s condition means he will soon be unable to climb stairs.
She added her son was known to neighbours who all supported the plans and the committee also heard they had the backing of Hull West and Hessle MP Emma Hardy.
But committee member Coun David Nolan said while he supported the application because of the family’s circumstances, it would likely have been “thrown out” had someone else lodged it.
Coun Ros Jump said the decision was one of “heads or hearts” but the plans could cause “aggraviation” with neighbours over parking once the St Johns moved on.
Coun Richard Meredith said the garden was too small and one of the home’s windows was next to a fence blocking sunlight, meaning it was not suitable despite him sympathising.
Ms St Paul told the committee their “unique” application could not be compared to others, adding the family lacked the means to move to a suitable alternative home.
The applicant said: “Jack was diagnosed at the age of two with life changing conditions, he has severe mobility and learning difficulties. There’s no option for a stairlift in our home because of Jack’s disability.
“The plan would be for us all to move into the home and help Jack prepare for when we move on, it breaks my heart to think about it.
“I work for the NHS and the coronavirus pandemic has made me realise the importance of preparing Jack for an independent life.
“Residential care isn’t an option for him, these plans are for Jack when he doesn’t have family around him, they’re not about financial gain for us.”
Coun Nolan said: “This is a difficult one because of the circumstances, purely on planning grounds this would be thrown out.
“But this is an exception, there’s personal mitigating circumstances here and the family’s made this application because an annex on the house would not provide what’s required.”
Coun Caroline Fox said: “Now and again we’ve got to look at the bigger picture, there will probably be more and more of these sorts of applications coming forward in the future. But I wonder if they could look at something different and come back to us.”
Coun Jump said: “I fully understand where the applicants are coming from, but the driveway is exceedingly narrow.
“Number 62 will be left with no parking of any consequence, my concern is what happens when the family moves on, it’s a good idea but it’s in the wrong place.”
Committee chair Coun Nigel Wilkinson told the applicant following the decision: “As some councillors have said please come back with an alternative and we may look at this totally differently.”