I have seen many problems in residential, commercial and industrial buildings as well as infrastructures. Well, all types of defects are common. Problem is, not everyone can know or identify the defects. So, most likely they will suffer in long run.

For new house, you have DLP but it won't do you any good. Sad to say, not all developers and contractors will really solve the problem but they will just solve it for you in a short term (cheaper and faster method) or drag until DLP ends. Trust me, a laymen will not know which is better method. Worst, if you started renovation or re-sale, there might not be DLP anymore. so make sure you read your S&P well before you do anything.

For old house, renovation is tricky. it can cost you a fortune if you overlook on certain things, especially for terrace and semi-D or linked house. you won't know what is coming next.. defects still can be repaired. but damage to nearby structures can cost you tremendous amount of money. do you know other nearby houses or even Majlis can charge or sue you if they find anything wrong to their structures ? i came across such cases where renovation contractor just run away where you can't contact them anymore and etc. and then, defects is another headache.

My suggestion, get 1 professional company to be in charge of all this for you ie from the beginning until whenever you need... you don't have to remember so many phone numbers and get "worked" up over small matters. Just deal with them for the defects identification, repair, design, renovate, construct and DLP ... there are lots of such company in malaysia, i think. but reliable one ... make sure you know them and their reputation well. must see what the boss qualification is and their experiences ....