A long duration may secure a low monthly instalment, however total interest will be much higher. On the other hand, a shorter duration results in less interest but leads to a higher instalment. Therefore, the duration you choose should set your instalment at such an amount that any eventual change in your income or any contingency does not jeopardise the servicing of the loan.
To help you deal with the expenses associated with a new house, especially in case of construction, you may opt for a grace period of up to 24 months. During that grace period, you can pay the loan interest only or not pay it at all by incorporating it in the loan amount. However, please note that in the latter case, total interest charges will be higher.