Ha ha, not to worry my friend. My upstair neighbour dog bark 24/7. i also LL. Next time they complain, ask them to move to a big land bungalow deep in the JB forest, such quiet till they scare. Anyway, it's your own house, no permit required. U can drill as many holes as u want. Else who will buy from IKEA, all diy stuff. Just minimise noisy work after 5.30pm or weekend. Anyway just Google for HDB permit.