File writ petition in HC against MCD failure to take action against illegal construction done on terrace and for demolition of unauthorised construction 

2) also file RTI with MCD as to what action has been taken on your complaint 

See you can file a suit before civil court along with the interim.stay application pending the suit .

See if the document is registered you can get certified copy of same from.sub registrar office where it was registered.

Further notice at this stage is not required proceed.for suit.

1. You can file a Police FIR, requesting investigation and charge-sheet, for offences like cheating, intimidation, breach of trust etc.... against the person, supported with all relevant supporting documents.

2. IF the Police does not take action, THEN you can file private criminal case u/s 156(3) Cr.P.C., in the local Magistrates court, seeking directions to the Police to investigate and file charge sheet. The said Person may come down for settlement.

You can send him notice and approach the court for the same

Firstly, you should give written complaint to MCD. Once that has been once and still they do not take any action against the fourth floor owner, you can file an application under RTI act to enquire about your complaint and as to what action has been taken in that.

They would be bound to give you a reply in writing and high chances are that devil seal the illegal construction and imposed penalties upon the person concerned.

Terrace comes under common area and jointly use by all and cannot be put to use for personal accommodation. Don`t allow labor to enter in the building.For any force, call the police.

, File injunction suit.

Copy you will get by applying at sub registrar office - certified copy.

you can file civil suit and file for interim injunction. 

you can get certified copies registration documents from Sub Reg Office. 

issue a legal notice through an advocate and file for interim Injunction immediately. 

If this constructions is totally illegal and against the building bye laws of MCD, approach the High Court against MCD challenging their inaction in the present matter despite your making a detailed representation before it. 

You can file a mandatory injunction suit seeking to remove the illegal construction built on the terrace against the conditions of the sale deed and also to restrain him from putting up any construction  on the terrace till the disposal of the suit.

Since you have sold the porperty by executing a registered sale deed in his favor, you may apply for the certified copy of the registration document from the registrar's office.

You can contact a local advocate for issuing a legal notice in this regard.

Dear madam

Send him a legal notice through an Advocate for stoping the construction over the terrace as per registry conditions. 

If he doesn't stop the construction file a suit for permanent injunction against owner of 4th floor for stopping the construction on terrace through order of court. After court order police and municipal corporation will help you stop the construction.

1. As per the information mentioned in the present query, makes it clear that you have a clause in the contract, but don’t have the copy of the same.
2. You can get the certified copy of the same by making application before the registrar’s office fo your district after making nominal fees to the authority.
3. And then you can approach the civil court of law for the enforcement of the contract and putting injunction against the illegal construction.
4. It is no useful to approach the MCD as this would consider to be the private dispute and no illegal encroachment.
5. And in fact, making of fourth floor is not permissible a per by laws of MCD in Delhi, so it might affect the property also if MCD comes into the picture.