For my case, there were wet patches seen near the ceiling in the common toilet and the kitchen pipe.. The HDB officer came to take a look.. Less than 3 weeks later, I received a letter from HDB, to authorise the repair and in my case, inform me of the estimation cost.. HDB will pay 50%, my neighour on top of my unit and I 25% each... My flat is a 3NG.. The cost (in my case, the common toilet) is estimated to be $800 and I am supposed to pay $200 (maximum)... I replied them last month and I have not moved into my house yet, so I am not sure, if they have started the reno yet or not...