On the outside, this white apartment building in Keng Lee Road near Novena looks no different from its neighbouring blocks.

But while the other buildings consist of several smaller apartments with different owners in them, this 12-storey building, with its distinctive onion-shaped domes on the roof, belongs to one family with three generations living under the same roof.

Businessman Mohamed Haniffa, 70, built the apartment block to house his family of 15 and five household helpers.

His family includes his wife, Siti Zubaidah, in her late 50s; their five children, aged 24 to 35; and eight grandchildren, aged four to 14.

The family used to live in a three-storey bungalow on the same plot of land, before moving into their new $9-million apartment building in January.

'I built this apartment block because I want all our children to live in one place,' says Mr Mohamed, chairman of textile and garment company Haniffa.

While having five families living under the same roof is unusual, multi-generational families living together are not uncommon.

Part-time barista Jann Pua, 60, lives with her daughter Gillian, 34, and her family, which includes Gillian's sales engineer husband Kenny Chua, 34, and their 17- month-old daughter, Corrinne.

The family has been living together in a five-room HDB flat near Tiong Bahru for the last five years. Madam Pua has her own bedroom, while the baby sleeps with the couple.

'I must live with my mum because she is alone and I need to take care of her,' says Gillian, a network engineer, who lived with her mother in a rented flat before she got married.

Mr Chua's parents live in the opposite block. Having both sets of parents in close proximity has been a good move. Earlier this year, Corrinne was diagnosed with diabetes.

'Luckily, we have my mum living with me and my in-laws nearby. They all help to take care of Corrinne,' says Gillian, who prefers to depend on family support rather than send her baby to a childcare centre or employ a maid.

Engineer Kok Chuen Wah, 34, continues to live with his parents in their five-room HDB flat in Bishan even though he is married and has a daughter, Leia, one.

His wife, Loh Wai San, 34, an administrative executive, moved in when the couple got married in 2007. The couple did not move out because they are happy living with Mr Kok's parents, a retiree and a housewife, and could not find a suitable flat for themselves.

'Living together has strengthened our family ties. My daughter adds colour to family life,' says Mr Kok.

He trusts his parents to care for his child, 'but should anything happen to them, it's easy for my wife and I to, in turn, care for them too'.

The couple have plans to move out on their own eventually but feel that the new home should still be within walking distance of their parents' home.

Living in a multi-generational family may mean an extra pair of hands to help around the home, but sometimes, life may not be that rosy.

Secretary May Tan, 29, used to live with her in-laws but has since moved out.

'I'm grateful to my mum-in-law for helping me care for my daughter, but we have different ideas when it comes to bringing up a child,' she says.

She and her manager husband Peter Kok, 31, moved out on their own last year. Her mother-in-law still cares for their daughter, Karen, two.

'We are no longer under the same roof, so there's less chance of us quarrelling,' says Ms Tan.

Family and marital therapist Benny Bong from FamilyWorks says there are advantages to having a multi-generational family living under one roof, such as help with meal preparations and child-caring duties.

But for such families to live harmoniously, 'all parties should recognise that some relationships need more space than others', he says.

For example, elderly parents should recognise that their children may still want their own time and space, and vice versa.

He adds that the 'newcomer' to the family should also acknowledge that what works in his own family may not work in the new one.

Mr David Kan, executive director of Family Life Centre, says that in a multi-generational family, 'it's better to work on understanding others, rather than seek to be understood'.

This article was first published in The Sunday Times.