Firefighters tackled the blaze at the terraced home in Fawcett Road, Southsea, at around 4am this morning - with police now probing the incident.
The home’s door was ripped out of its frame as crews burst in to douse the flames.
Police have not commented on the incident.
But terrified Parkinson’s sufferer William Payne, 72, told The News how he was stuck in bed at the home he has lived in for a lifetime.
He said: ‘I was fast asleep at about 3am, suddenly the bell rang. I’m a very light sleeper and I thought it was a mistake.
‘Then all of a sudden it was bang, bang, bang and the bell rang and it went on for about half an hour.
‘I was petrified, then all of a sudden there were firemen everywhere - they said the house next door was burnt down.’
He added: ‘They said if the fire had come through the wall it would have come right through here. I’m only here by the skin of my teeth.’
Firefighters said the entire property was damaged by the fire, which was ‘well developed’ when crews arrived at 3.57am and it was out by 5.30am.
Neighbours in the street, near to Albert Road, have said they were shocked by the blaze.
A 52-year-old man, who did not want to be named, said: ‘I’m shocked, surprised - you just don’t know what’s around.’
Self-employed Jeremy Young, 52, added: ‘It can be a bit scary.’
Pensioner Mr Payne said he was worried about the fire being suspicious. He said: ‘I was born here in this house 72 years ago, I’ve never moved anywhere and when I was a child it was a pleasant, peaceful area full of children, trees and fun, and Albert Road had little shops. That’s all gone.’
Clairvoyant Mikquita Morgan, 56, who leaves across the street said: ‘What surprised me was I didn’t hear anything.’
She added: ‘I honestly think it was set deliberately.’