Dear Manish,
You first need to classify it as construction service or works contract. i.e. if the contractor uses its on Material and Labour and doesnot disclose seperately in the invoice then it will be classified under works contract Service & if seperately disclosed then labour portion will be classified under construction service and on material portion VAT Needs to be paid.
Construction service in not covered under reverse Charge Mechanism but Works Contract Service is covered under reverse charge where 50%-50% service tax liablity is to be discharged by both Service receiver and Service Provider if service provider is Individual/HUF/Firm. ETC
thanks