Norma Mnassakh was leaving her apartment in the Lebanese capital when a cloud of dust suddenly billowed from the Ottoman-era building next door.

The abandoned home with its popular ground-floor ice cream shop had been severely damaged in the colossal August 4 explosion at the nearby Beirut Port.

Now, heavy rainfall has just about finished off the job.

"I was born and raised here. This neighbourhood is home. I know every single piece of it," the woman in her fifties told AFP, only hours after the building partially caved in.

"But I'm losing all the sights that I grew up with," she added, as chunks of rubble lay strewn on the sidewalk.

Rmeil 24, in Beirut's Ashrafieh district, is among a handful of structures damaged in the blast that collapsed this week with the start of heavy rains and wind.

At least 90 other heritage homes could bite the dust this winter, caretaker culture minister Abbas Mortada told AFP.

The port explosion, which authorities say was caused by a huge stockpile of ammonium nitrate that caught fire, killed more than 200 people and damaged or destroyed around 70,000 homes.

Now, the weather is worsening that destruction.

Carla, a 52-year-old who grew up near the Rmeil 24 building, said Lebanon's history was on the line.

"This is our heritage," she said.

"It's such a shame for it to be lost in this way."

Too little, too late 

The Rmeil 24 building has been abandoned for more than 40 years.

But its ground floor continued to house the Hanna Mitri ice cream shop — one of the capital's most prized traditional parlours, beloved by tourists and locals alike.

The Beirut gem, which has since reopened in a new location, was forced to shut after the explosion caused the shop's ceiling to crumble.

Heavy rainfall on Thursday night accentuated the "cavities in the roof" of Rmeil 24, leading to the "partial destruction" of the building, said Yasmine Makaroun, an architect from the Association for Protecting Natural Sites and Old Buildings in Lebanon.

The worst could have been prevented if the landowner hadn't delayed access to the site while the weather was favourable, she told AFP.

"We could have started the first rescue interventions... and we could probably have partially saved it," she said.

The cash-strapped Lebanese government, which is grappling with the country's worst economic crisis in decades, is relying on foreign assistance to protect heritage buildings from collapse.

But Western donors have pledged to bypass the government after allegations of corruption and mismanagement, instead channelling funds directly to local and international organisations spearheading the reconstruction effort.

Caretaker Culture Minister Mortada said international assistance had been underwhelming.

"We are not seeing the required level of interest... from international organisations," he told AFP.

And "as a ministry, we have a gap in capacity," especially regarding personnel, he added.

In the Gemmayzeh neighbourhood, just across from the port, labourers worked to remove the remains of a building where Chilean rescue workers in September thought they had detected a human heartbeat beneath the wreckage.

The building was severely damaged in the explosion, and rains on Wednesday finished it off.

Workers outnumbered pedestrians, who walked nervously past several buildings along the street that looked like they could collapse at any moment.

Just over a kilometre away, the working-class Karantina district adjacent to the port was already a wasteland of debris before the rain brought a building down on Wednesday — the first such casualty to the winter weather.

Security forces watched on as construction workers fortified the walls of another building at risk of collapse in the hard-hit neighbourhood.

All around, the entrances to old homes were cordoned off with yellow and red tape. Signs warned people against entering.

Staring up at a gutted building overlooking the devastated port, one Syrian refugee who asked not to be identified lamented his lost home.

"There is nothing we can say," he told AFP.

"We can only turn to God."

By Hashem Osseiran