The GRIHA online calculator displays the NBC Imperviousness threshold value for commercial buildings as 70. However, the range in the GRIHA manual has been mentioned as 70-90.
The project team had designed the site as per the GRIHA manual whereas there is a difference in the values displayed in the online calculator. .
Kindly let us know whether the values for net imperviousness factor will be accepted as per GRIHA manual.
The GRIHA website displays only the minimum threshold for the imperviousness factor, as per NBC. Hence, the project claiming imperiousness factor ranging between 70 - 90 % will be accepted for compliance on submission of relevant documents.