1. under law, a garage is not an independent unit or a flat.
2. it is an attachment to an existing flat
3. so the member owning a flat with a garage attached cannot demand extra carpet area on the basis that he is also entitled to the garage alongwith the flat
4. however a garage is a set of premises which is covered on 4 sides ie has a roof and 3 walls. Obviously for constructing the roof and 3 walls, FSI must have been used. So the contention of some members that a garage has no value is not correct
5. as you cannot demand extra carpet area for the new flat on the basis that you also own the garage, what you can certainly demand is a monetary compensation for the garage
6. also keep in mind that if the members who are holding garages as well demand extra carpet area for the new flats, then the builder will have to specifically plan for such few flats in the building plans. this results in planning constraints for the builder and may not be practically viable. a builder would proceed on the basis that to compensate the members in lieu of their old existing flats he will have to construct new flats having carpet area comprising of old carpet area of old flats plus agreed extra carpet area. so he would uniformly build such new flats for all the members. if he is asked to build few flats having extra carpet area due to demand by certain members for extra area in new flats on basis of them holding the garages, then it will be very difficult for the builder to plan that out architecturally
7. yes off course a society may not have all the flats having same carpet area. for instance a society may have 3 types of flats of different carpet areas say 1RK, 1BHK and 2BHK. The builder would accordingly plan the new building in such a way that he would be able to compensate the society members by allotting new flats of 3 different carpet areas corresponding to the existing flats' carpet area. Now if within these 3 categories, if one more category is added due to say few 2BHK flats also having garages attached to them, then, this would result in planning anomaly for the builder.
8. So you must demand compensation in lieu of your garage whether in the form of extra corpus or separate consideration against the garage.
9. Even if the society proceeds for the redevelopment without addressing the garage issue, you can always challenge the same in court. you can submit that you are not against the redevelopment and are not at all obstructing the same but you must be compensated against the garage and the builder ought to pay you for the same.
10. if society has appointed a PMC, and it bypasses the PMC, then you can challenge such decisions. Why was PMC appointed in the first place when society was not to consult it for any redevelopment issue? This is the question you need to ask to the society