A 64-year-old man who had a weak knee fell 11 floors to his death while standing on a stool to carry out some maintenance work along a common corridor.

A cocktail of illicit drugs was later found in Mr Ali Amat Awang Chik's blood.

A forensic pathologist said these substances, which had no direct role in Mr Ali's death, could have decreased alertness and caused dizziness, confusion, agitation and other symptoms.

Giving his findings into Mr Ali's death yesterday, State Coroner Marvin Bay said the unemployed man's sense of balance may have been thrown off by his weak knee, awkward working position on the stool and the effects of the drugs.

Said Mr Bay: "He had very possibly lost his balance while on his precarious perch on the black stool. Having lost his balance within the confined space, he had likely fallen over the parapet and sustained his fatal injuries."

The coroner said there was no basis to suspect foul play. He found Mr Ali's death to be an "unfortunate misadventure".

Mr Ali had a medical history which included hypertension, migraine and osteoarthritis of his left knee.

On April 27 - 10 days before his fatal fall from his block in Bukit Batok East Avenue 5 - he was arrested for stealing a gold chain and consuming heroin. He was released on police bail, pending investigation.

The inquest heard that on May 7, Mr Ali was at home when he told his wife, Madam Sutinah Hamzah, 57, that he wanted to remove a bamboo pole hanging along their corridor, and also certain screws from the top of the wall that he used to secure his bird cages.

Five to 10 minutes later, Madam Sutinah, a retiree, heard a loud scream outside.

She searched for her husband but could not find him.

Instead, she found his slippers, tools and a black stool along the corridor.

Peering over the metre-high parapet, she saw her husband lying on the grass patch on the ground floor.

A toxicological analysis found amphetamine, chloroquine, methamphetamine and morphine in Mr Ali's blood after his death.

Coroner Bay said Mr Ali's death calls attention to the need for home owners in high-rise apartments to be mindful when they do maintenance work along the common corridor and other spaces outside their units.