Two stories house in a single storey house area?

One month ago when cycling, I noticed a double stories independent house being build in a single storey housing area in Piasau Garden, meaning in the middle part of the area where all the houses are single storey. Would like to ask :

  1. Whether there has been any rules change that allow the house to be built double stories in the area?
  2. Do they apply for permit to build the double stories house?
  3. As far as I am aware, the section could only build single storey house and even with additional extension to the house etc permit need to be apply and approval from MCM required.

The house is at the area around No. 2xx at Piasau Garden. Honestly I am shocked to find the house being built double stories instead of single. Information require please from netties before I write in to MCM or whatever dept. it is that is in charge of the issue to complain.

Appreciate your help.