The key concept you must understand is that UDS represents ownership of land, while flat area represents the building constructed on that land. The two are related but not always identical in older buildings.

When a building is demolished and reconstructed, the legal ownership of each owner is determined primarily by the UDS mentioned in the sale deed.

The legal position is that the Land ownership governs redevelopment rights. If all 17 flats have equal UDS, then legally all 17 owners own equal share of the land. Therefore in strict legal theory each owner has equal land rights. 

Current norms (RERA practice and modern development rules) say that the UDS should be proportional to apartment size, but this applies to new projects and not to buildings already registered decades ago. Your registered sale deeds remain valid.

Your question is whether a 500 sq.ft owner demand 1200 sq.ft now?, yes he can claim  based on his arguments that since my UDS is equal to yours, my share in the land is equal, so I should get equal constructed area.", because equal UDS = equal land ownership. This argument sometimes arises in redevelopment disputes.

But in practice courts look at existing arrangement, courts generally respect the existing pattern of occupation and agreement among owners.

If for 45 years Flat A = 1200 sq.ft and Flat B = 500 sq.ft, then redevelopment normally maintains the same proportion unless everyone agrees otherwise. Courts rarely disturb long-standing arrangements unless there is fraud.

For self-redevelopment the safest legal method and  to avoid disputes, the association must execute a Redevelopment Agreement among all owners. The agreement should clearly specify existing flat area, reconstruction entitlement, and also clearly state that each owner will receive same or proportionate built-up area as existing and not based on UDS. 

Example clause: "Each apartment owner shall receive a reconstructed flat equivalent to the existing built-up area presently occupied."

If you do not document this properly, a future dispute can arise where someone claim  like my UDS is equal, so I want equal flat area.” Therefore the agreement must clearly override that argument.

It is important that all the 17 flat owners should agree that because  UDS is equal, the redevelopment decision should ideally be unanimous.

If there is a dispute, the case can become complicated since everyone owns equal land share.

The 500 sq.ft owner cannot legally demand the same size as the 1200 sq.ft owner solely based on equal UDS. Redevelopment is meant to rehabilitate owners, not create ownership disputes

2)Your original sale deeds are legal proof of ownership. If the sale deed mentions a specific super built-up area along with a UDS value, that ratio represents your holding.

3)  Redevelopment Agreement  has to be entered into approved by a majority of flat owners 

4)If the 1200 sq.ft owner gives up their higher existing area to make all new flats uniform (e.g., all 900 sq.ft), they must be compensated with higher corpus funds or preferential allocation (e.g., better floor, corner flat).

In older apartment developments in Chennai and similar cities, it is quite common that the Undivided Share of Land (UDS) mentioned in the sale deeds is the same for all flats, while the built-up or super built-up area of the flats differs. Such arrangements were legally permissible at the time when many of these buildings were constructed, particularly several decades ago.

For the purpose of self-redevelopment, the most important legal factor is the existing registered sale deeds of the owners. The UDS recorded in those deeds determines each owner’s proportionate ownership in the land. Since in your case the UDS is equal for all owners, legally each owner holds an equal share in the land irrespective of the size of the flat that currently exists in the building.

However, this does not automatically mean that every owner must receive the same flat size in the redeveloped building. In redevelopment projects, the allocation of flats is generally governed by a mutual redevelopment agreement among all co-owners. If all owners agree to retain the current pattern where some flats are larger and some are smaller, such an arrangement can legally continue, provided it is clearly recorded in the redevelopment agreement and reflected in the new sale deeds or re-allotment documents.

At the same time, because the UDS is equal for everyone, technically each owner has the same proportionate land right. Therefore, if a dispute arises, an owner of a smaller flat could argue for a proportionate share of the built-up area in the redeveloped building. To avoid such disputes, the safest legal approach is to obtain written consent from all owners confirming the agreed flat sizes in the redeveloped structure.

In practical redevelopment planning, the following steps are advisable:

• Prepare a registered redevelopment agreement signed by all flat owners.

• Clearly record the flat allocation plan, specifying which owner will receive which flat and the approximate carpet or built-up area.

• Mention that the allocation is made by mutual consent despite equal UDS in the original deeds.

• Update the new apartment deeds or re-conveyance documents accordingly after reconstruction.

If all 17 owners voluntarily agree to the proposed allocation and execute the redevelopment documentation properly, the present differences in flat sizes can legally continue in the new building without violating current regulatory norms.

Dear client,
Your apartment was built 45 years ago, and there are sale deeds that specify the Undivided Share of Land (UDS) for each of the owners. While the UDS is the same for all flats, this does not mean that the square footage of each flat will also be the same as the square footage of each flat varies from one flat to the next. The legal standing is primarily governed by the deed documentation that is registered with the state and the mutual written agreement of the respective owners.

According to the Tamil Nadu Apartment Ownership Act, 1994, UDS indicates a measure of land, but not in terms of how much square footage each flat is. In many old buildings, same UDS amount but different super built-up size are common. The law generally accords the original sale deed and with the longstanding possession of the owners.

When the owners undertake self-redevelopment of the building, they can mutually agree on how the new flats will be allocated. All owners can agree to maintain the same amount of square footage per flat (for instance, one owner of a 1200 square foot flat would get a new, larger flat; and an owner of a 500 square foot flat would get a new, smaller flat) even though the UDS are the same.

An owner of a 500 square foot flat does not have the right to demand to that the 1200 square foot flat owner give him the 1200 square foot flat due to the UDS being the same unless the owners mutually agree to redistribute the square footage.

To help avoid problems in the future, whenever the owners do agree to redevelop the building, there should be a registered Development Agreement that clearly spells out the square footage, UDS, and distribution of flats in the new building. This will protect and save everyone legally.

If you have any query please feel free to contact us

It’s as per the agreement of the developer and agreed terms. If you dispute the same then it can be challenged