Section 39(8)(d) in Tamil Nadu Combined Development and Building Rules, 2019
(d)The basement shall be permitted below the ground and beyond the building lines at ground level subject to a clear minimum front setback space of 4.5m and side and rear setback of 3m, subject to non habitable uses and provision for mechanical ventilation and all safety provisions and drainage. However, it is essential that the basement top slab below the external circulation at ground level should be designed for firefighting vehicular loads