I used to be involved in renovation projects before I moved here and have been looking in to setting up a similar operation in Singapore. However I am still not convinced that there is much of a market for it. Most people who purchase a property
are either buying new builds or buying a house for the land. They then knock the property down and build a new one.
Older properties that could do with renovation tend to be rented out and as such the owner is not inclined to spend much money on renovating or updating the premises other than a lick of paint.
It would also take you some time to get a reputable group of contractors to work with. The best ones, given all the housing work, ar full. Then there is the language issue.
Having said all that, I do believe there is an opportunity at the higher end of the market...you will just need to do a great deal of networking and maybe it will pay off. Good luck though.