One neighbour, who did not want to be named, said he noticed the smell a few days ago. He said he told his friends: "I think there is a dead body in there."
No words could describe the smell coming from the man's house, the neighbour said. Although he didn't know the dead man well, he said the man was "harmless" and had been in the area for only a year or so.
The neighbour believed the man shared the house with his wife and she was there when police discovered the body on Sunday.
Last night police were unable to confirm whether there was another tenant living at the property, or whether there was anyone else at the house when the man's body was found.
A Housing New Zealand spokeswoman confirmed the agency owned the property.
However, she said the discovery of the body was a police matter, so no further comment would be made at this stage.
Yesterday, Detective Senior Sergeant Grant Ferguson said an initial examination showed the man might have been dead for some time.
Neighbours said they expected he had been dead for at least two weeks.
Mr Ferguson said police investigators were still working to unravel the circumstances leading to the man's death.
"The immediate focus of the investigation is to examine the scene and the body, after which we should have a better idea of what has occurred.
"It is important that a cautious approach is taken at this stage, so we can do the best job possible for the deceased's family."
A woman who lived directly opposite the man said she was "shocked" and "scared" after hearing about his death.
She said she had no idea what had happened, but she had seen police "parked everywhere".
Porirua Deputy Mayor Ana Coffey said her mother lived in the same complex as the dead man.
"I know the neighbours couldn't figure out where the smell was coming from. "
She said neighbours were known to "look after each other".
"They all know of each other because they live there - I don't know how well they knew each other."
She said the man's death had left the community saddened.
"It is sad and it is really shocking, to know that someone passed away. I guess it is about ... hopefully respecting his family, his life and hopefully we'll get to hear some of the good stories about his life rather than the sad ending."
The discovery comes after three other social housing tenants in the Wellington region were found dead in their homes well after their deaths.
In January Dean Richard Stewart, 63, a tenant at Granville Flats in the Wellington suburb of Berhampore, was found dead in his home. He had been dead for some time.
In 2009, Wiremu Whakaue, 68, died in the same flat Mr Stewart was living in when he died. His body was not discovered until March 2010.
The body of 87-year-old Michael Clarke was found in his one-bedroom flat in August 2011, more than a year after his death in July 2010.
All three men lived in properties owned by the Wellington City Council.
Social housing deaths
•August 2015: A man's body is discovered on the floor of his Titahi Bay home.
•January 2015: Dean Richard Stewart, 63, was found dead in his home at the Granville Flats in Berhampore. He had been dead for some time.
•August 2011: The body of 87-year-old Michael Clarke was found in his one-bedroom flat in Newtown more than a year after his death in July 2010.
•March 2010: The body of Wiremu Whakaue, 68, was found in his unit at the Granville Flats in Berhampore. He died in 2009.
