What were the costs involved in building Calhouns Green Roof?
Intensive Green Roofs are, by their very nature, more costly and demand more maintenance than their extensive counterparts. The hard costs for Calhoun’s Green Roof–not including design services–were approx. $60 per square foot. Architect’s and structural engineer’s fees were additional because the Green Roof was not part of the original project, and it required some structural modifications. In comparison, FXFowle Architects says that material and installation costs for a roof without irrigation and with a 4-6″ soil depth (sufficient to support some non-turf) might run $25 per square foot (but it’s important to remember that each case is different.) An existing building must be tested for stressing and may need to shored up. Many New York City buildings built after 2000 may be fine, depending on the soil depth desired.
