Can go for extension if the extension comply to law. However, this is still a grey area. Some people they extend without approval from local council, some do. So it all depends what you want to extend and how big it is.

Bigger land of course better value la when you sell. You can build a small balinese hut, fish pond, small garden etc which will lift your property outlook thus directly increase your property value.

Aiya boss, now i saw your post, i need to apologize to TS. I saw it as an individual title. If strata title, one has to adhere to the management corporation house rule similar with those apartment or condo, and as what @michaellee has said. My apology again, TS.