30% for second hand property, if relation with bank are good, apply for another loan (higher in interest rate and normally shorter in repayment). New property usually got favor, 10% + whatever excuses for another 20% (may be same interest rate/terms or may not) provided by most banks. Monthly repayment+ traffic cost + daily outgoings + child care or Phil maid + food + working cost, barely enough. But why Tuen Mun??