You cannot enclose garden area as it forms part of common area for benefit of all flat owners 

you cannot legalise it 

If you have purchased the garden area by a registered sale deed, then you can claim ownership of the same as a right. 

If you have made an agreement with the vendor about it and on his verbal or unregistered authorisation or agreement, you cannot claim ownership to the common area.

The garden area and other common areas belong to the apartment owners association and all the members are equally entitled to a right over it hence you may obtain a proper legal opinion from a local lawyer by producing all the relevant property documents and proceed as suggested. 

It is generally not permissible to use common areas in an apartment building for personal use. These areas are typically designated for use by all flat owners, and any private usage of these areas is not allowed. 

Builder cannot sell garden area 

sake itself is illegal 

Dear client,  

Whether enclosing the garden area is legal or not depends on several factors, including local zoning regulations, building codes, and the terms of your agreement with the previous owner. It is possible that the enclosure of the garden area may have violated some of these regulations, and if so, it may be considered illegal.

To make the enclosure legal, you would need to take the necessary steps to obtain any required permits or approvals from the relevant local authorities. You may need to consult with a local attorney or real estate professional to determine what specific permits or approvals are required in your area.

Additionally, you may need to update your agreement with the previous owner or have a new agreement drawn up to reflect the changes to the property. This could involve negotiating with the previous owner or working with a real estate attorney to draft a new agreement.

If you have already paid the stamp duty registration for the entire area, including the enclosed garden area, you may need to update the registration documents to reflect the changes. Again, you may need to work with a local attorney or real estate professional to ensure that the changes are properly documented and registered with the appropriate authorities.

In any case, it is important to ensure that you are in compliance with all relevant regulations and that you have all necessary permits and approvals before proceeding with any changes to your property. This will help to ensure that your property is legally and properly registered, and that you do not encounter any issues or penalties in the future.

If you have a registered sale deed selling the said property ( if it is allocated to garden purpose or has been earmarked as property for other issues in the approved plan), then you can approach the builder for refund of the illegal sale of the property pertaining to common area.

If the said property is not mentioned as garden area in the plan approval and mentioned as private place belonging to the builder then the purchase can be termed as legal. 

Yes completely enclosing the same is illegal. But temporary enclosure can be put

All flat-owners are entitled only to an undivided share (UDS) of the land, apart from the exclusive and absolute title and ownership of the super-built flat. As such, garden forms part of the common area meant for the common benefit and enjoyment of all the residents. Even if  a garden area is mentioned in the sale deed, it is illegal.

you will have to check the sanctioned building plans

if in the approved plans the garden is showing then it cannot be enclosed even if it be sold by the builder to the purchaser

for enclosing the garden the Municipal Commissioner's permission will be needed

in absence of the permission the enclosure is illegal and in violation of the approved/'sanctioned building plans

mere stating garden as sold in the registered sale deed would not make the enclosure legal