Cost of Improvement

Improvement is usually structural repairs / renovations. Your painting (plastering etc.) and flooring, bathroom etc. could be considered as an improvement as they are part of the structure. A rolling shutter added to a shop is also a structure added. As far as item of furniture are concerned,the only item that can be considered an improvement is if you make a permanent wooden partition in the structure like making 2 bedrooms into 3 or 4, dividing 1 bathroom into 2.

However, I would suggest not to go through all that. They usually ask for architects or structural engineers certificates and such things for all the repairs you carry out structurally. For simple things like painting and flooring change or even improvement to bathrooms etc. they may allow you on bills of items and contractor.