Dear Mr CA Gaurav
Answer to your query lies in Expalantion 1 to the Rule 2A of Service Tax (Determination of Value) Rules, 2006 – Valuation Rules
"Original works" means-
(i) all new constructions; (ii) all types of additions and alterations to abandoned or damaged structures on land that are required to make them workable; (iii) erection, commissioning or installation of plant, machinery or equipment or structures, whether prefabricated or otherwise;
Other than above falls under Othe category for example which includes i) Maintenance or repair or reconditioning or restoration or servicing of any goods; or (ii) Maintenance or repair or completion and finishing services such as glazing or plastering or floor and wall tiling or installation of electrical fittings of immovable property.
In my view your company is providing Finishing works and abatement is 30%. Hope it is clear