The Gohs and the Tans used to enjoy a close relationship as neighbours, their two-floor semi-detached houses joined by a centre wall. But over more than two years, both parties slowly drifted apart - literally.
A crevice in the conjoining wall of house units 44 and 46 at Jalan Raya in MacPherson first appeared in 2013 and slowly grew wider and taller.
Running the entire height of the house, the crevice cleaves the structure in half. At its widest on the second floor, one can comfortably fit a fist into the crack.
Every so often, the house occupants said they would hear loud snapping noises and sounds of falling debris from their conjoining wall.
When it rains, water would gush into the widening crack and spring out from smaller gaps in the concrete wall, they said, leaving a trail of more debris on the floor.
Ms Goh, who had rented unit 46 for about four years, moved out in April because she was concerned over safety, returning the home to her landlord, Madam Ngiow Lee Kim.
Her former neighbour, Ms Tan, owns unit 44.
Both parties have declined to use their real names.
The New Paper met up with the housewives last Wednesday at a happy reunion - their first since Ms Goh's relocation.
The 45-year-old former tenant said: "It just got worse and worse. We had to get out and find a new place so that we can feel safe.
"No person would want to live in a house like this."
Ms Tan, who is in her 70s, said: "At first, we were fearful that the house would just collapse.
"Now we are just frustrated at the whole situation."
But the situation does not look like it will be resolved soon, said Madam Ngiow's husband, who declined to be named.
He told TNP that the damage is caused by his unit sinking into the ground while Ms Tan's unit remains stable.
Building plans show that his side of the house sits on a weaker foundation - concrete footings that have existed since the 70s - while his neighbours' unit rests on stronger reinforced concrete piles.
He added: "But the house was in good condition until two years ago. It means there was nothing wrong with the original foundation of the house."
TRIGGERED BY MRT WORK?
Madam Ngiow's husband believes the trigger to be the nearby construction site.
Excavation works for the upcoming Mattar MRT station on the Downtown Line 3 are being carried out and scheduled for completion in 2017.
The timing of the damage was around the same time that the works began, he said.
He is claiming nearly $290,000 in damages and lost rental income from the Land Transport Authority (LTA), which oversees the works at Mattar station.
But LTA has denied responsibility for the damage, it said in e-mails to the landlord. (See report, above.)
LTA said his unit is 150m away from the edge of the excavation, which is "beyond the 60m extent of influence zone".
The 30m-deep excavation also has not affected other properties, which are closer to the construction site than 46, Jalan Raya.
But Madam Ngiow's husband alleged that a pre-construction survey in 2011 done by the Mattar station's design team incorrectly showed that unit 46 sat on a pile cap foundation instead of footings.
He showed TNP documents over his claim.
Pile caps are stronger than footings as they are driven deep into the ground and can withstand more load.
TRIGGERED BY RENOVATION?
TNP understands that there could be another cause: The landlord could have added too much weight when he renovated the unit in 2008.
The landlord had filled in the basement with concrete, added an outdoor swimming pool on the first storey and built a new annex building at the back of the unit.
When asked about this, the landlord said: "It is technically possible that the weight might be the cause but the works were approved by my professional engineer then."
Now, he just wants to tear down his side of the house and rebuild from scratch.
"This situation has gone on far too long and I have spent so much money trying to patch things up," he said.
For Ms Goh, moving to a new rented home with her family has given her peace of mind.
It is a far cry from living in 46, Jalan Raya, and tolerating the strange anomalies occurring around the house, including cracking floor tiles, a sinking front yard and heavy furniture vibrating vigorously in the house, she said.
She also had to live with numerous large steel beams put up by the landlord to prevent a collapse.
"Even if this place is completely fixed, I don't want to return. As nice as they are, the landlord has lost me as a customer," said Ms Goh.
As the unit has been empty since April, it is the occupants of 44, Jalan Raya, who have to live with the cracking sounds and leaking walls.
Ms Tan said: "For now, my side of the house is structurally safe. But if nothing is done, my home will become an open concept when that side falls away."
TUNNELLING TOO FAR TO AFFECT HOUSE: LTA
Since the cracks appeared, the Land Transport Authority (LTA) has been in touch with the landlord of 46, Jalan Raya, on possible causes of the damage.
A long chain of e-mails between the landlord and the Downtown Line 3 (DTL3) team spanned more than two years, with LTA insisting that faults were not caused by their construction works.
Many building experts, engineers and loss adjusters (people who determine if damages can be claimed from insurance) have also visited the site to inspect the damage.
Responding to The New Paper's queries, an LTA spokesman said: "The loss adjusters have made an independent assessment of the property and concluded that the faults on the property existed prior to the commencement of DTL3 works."
"The DTL3 tunnelling works were also carried out beyond 150m from the property, which would be too far away to have affected the property.
"Unlike the adjacent properties, which are built on piles, the house at 46, Jalan Raya, is built without piles and on marine clay that is still experiencing natural consolidation."
DIFFICULT TO DETERMINE WHO IS AT FAULT: PROF
When a house sinks, it is due to a process called "ground subsidence", says National University of Singapore civil engineering lecturer Chan Weng Tat.
"Ground subsidence is as the name says - the level of the ground has gone down over time. Broadly speaking, if you disturb the soil, ground subsidence will happen," explained Associate Professor Chan.
He said that the 60m zone of influence cited by Land Transport Authority (LTA) is a general guideline.
"LTA would have already put in measures to try and control the rate of subsidence. If the landlord wants to say that LTA has not done its due diligence, then he needs to back the claim with evidence."
Since many factors are involved in this case, it is difficult to determine who is at fault, he added.
Prof Chan, who lectures on construction, projects management and environmental impact, has this advice to the landlord: Consult a geotechnical engineer to look at the soil condition.
He said: "When it comes to situations like this, nobody should make any guesses.
"Either party will have to do plenty of testing to gather data on what actually happened."
This article was first published on Sept 30, 2015.
Get The New Paper for more stories.