Your answer to your query lies in rule 3 of the Building and Other Construction Workers Welfare Cess Act, 1998 where the cost of construction is stated as:
"3. Levy of Cess—For the purpose of levy of cess under sub-section(l) of section 3 of the Act, cost of construction shall include all expenditure incurred by an employer in connection with the building or other construction work but shall not include :-
—cost of land;
—any compensation paid of payable to a worker or his kin under the Workmen's Compensation Act '1923.
Therefore, I feel that whichever becomes immovable part of the construction, like doors, windows, grills, wiring seaverage, water and conduit pipes bulb holders electric swiches taps toilet seats washbasin, bath tub, paints etc. should be included in the cost of construction. However, the tubes bulbs, airconditioners inverters movable almirahs tables, chairs and furniture etc. etc. can be excluded.