Both Sengkang and Punggol are good places to rent, they are new houses, only problem is there are mostly 3 bedroom houses and many people rent 3 bedders and then rent out 1 room to somebody else.
HDB owner are hold responsible to ensure the unit is not further sublet to other people.
http://www.hdb.gov.sg/fi10/fi10323p.nsf ... enDocument
Guidelines for Renting Out the Whole Flat
Flat Owners’ Responsibilities
As a flat owner subletting your flat, you will be responsible for:
Making sure the flat is sublet to eligible subtenants only;
Making sure that there is no overcrowding and the number of subtenants does not exceed the maximum number allowed;
Making sure that your subtenants have entered and are remaining in Singapore lawfully at all times (while the subletting is ongoing);
Making sure that your subtenants do not further sublet the flat to other persons;
Making sure that your subtenants comply with all the covenants in the lease and the provisions of the Housing & Development Act and that you are responsible for all infringements, if any, committed by them;
Informing HDB of any changes in the subletting agreement;
Resuming occupation of your flat and ensuring your subtenants vacate the premises when:
The subletting is terminated, or
You are no longer eligible to sublet your flat; and
Surrendering the flat if the flat is repossessed by HDB.