Most of the architectural firms in Kerala charge based on the proposed build-up area of the project, This varies from ₹ 40 / sq. ft to ₹ 150 / sq. ft for residential units, COA guidelines for Single Block Housing and sites up to 0.5 hectares are 5 % on the cost of works for Comprehensive Architectural Services, and 7.5 % each for interior designing and landscape architecture, 1% on the cost of works assigned, to be computed at a rate of Rs. 6000 per Sqm of proposed built-up area, for urban design projects subject to a minimum of ₹ 240000. Learn more.