Bungalow to 2-Floor House for Resale in Chiang Mai ?

Is the bottom line that generally in smaller cities (not peak demand areas) there is not really a chance of any profit margin doing a conversion from 1 to 2-floor dwellings ?

House is in Wiang Kum Kam just south-east of Chiang Mai city proper....115M2 currently.
Any guys out here that have done design and build previously ?

Building is 5 years old and still in very fresh shape barring a few things that need freshened up.

There is also the tax question to be paid by here - as this is a 2nd dwelling in my partner's name....no idea what tax rate would be paid on sale of the house.