Demand for subdivided flats has mushroomed over the last decade, bolstered by immigration from the mainland and a recognition among owners that subdividing flats could make for big profits, says Institute of Surveyors spokesman Vincent Ho Kwok-kwan.
Older buildings are easier to subdivide than new ones, he says, making Sham Shui Po a hub for low-income housing.
"Units in old buildings are structurally more suitable for subdivision because they're usually rectangular shaped without too many internal structures," Ho said.
"Old buildings also often have looser property management compared to the tighter control in modern buildings."
And subdividing can also pay off for the landlords.
"The value of real estate is relatively low in Sham Shui Po; an apartment rental won't be near HK$10,000 a month," said Ho. "But if it is divided up into 100-200 sq ft subdivided units, which can be rented out for HK$3,000-4,000 each, that becomes a much more lucrative investment."
For a 900 sq ft apartment divided into nine homes, the rent could be HK$35,000 a month - four times what a single flat of that size goes for in Sham Shui Po.