The housing authorities are looking at whether the reinforcement bars for a dislodged sunshade were put in place following an incident at Tampines.
On Sunday, a 5m-long concrete sunshade outside a fourth-floor Housing Board flat at Block 201E, Tampines Street 23 dislodged partially and landed on the sunshade of the floor below. No one was hurt.
Responding to queries, HDB said one of the areas of investigation includes whether the sunshade had been installed properly.
Rebars are typically used to support a building's structure.
"The investigation outcome will allow us to recommend suitable follow-up measures," said HDB, and urged the public not to speculate on the cause of the incident.
As a precaution, detailed checks are also being carried out with Tampines Town Council in three neighbouring blocks with similar sunshades. They are Blocks 201A, 201B and 201D.
Town council staff also did visual checks of nine blocks in the area and found no physical signs of cracks, said the town council on its Facebook page.