The Housing Board (HDB) received 1,152 applications for 84 "three-generation" and 260 five-room flats in its latest Build-to-Order exercise, said National Development Minister Khaw Boon Wan on Wednesday.

Of these, a third came from multi-generation families. This is in sharp contrast to last year, where only 3 per cent of five-room flat applicants applied to live with their parents under the Married Child Priority Scheme.

HDB bundled the "three generation" flats and five-roomers so that applicants would have an "alternative housing option" if one type ran out, Mr Khaw wrote in his blog.

Among the 378 applications from multi-generation families, two-thirds were second-timers upgrading to a larger flat to accommodate a growing family or to live with their parents.

Of the first-timer multi-generation families, six out of 10 are either expecting or have young children below age 16. Their median age is 39, higher than the previous median age of 30 for first-time five-roomer buyers.

One in 10 of first-timer households had no children, with their median age understandably lower at 32. Mr Khaw wrote: "I am happy they are planning ahead to move into a larger flat to better take care of their ageing parents and future children."

The "three-generation" flats are units with four bedrooms and three bathrooms, and about 5sq m larger than current five-room flats.

"The launch of 3Gen flats has clearly encouraged more to consider multi-generation living," Mr Khaw wrote. "This is a good sign."