This work aimed to characterize the rigid polyurethane foam extracted from castor oil (Ricinus communis) for application as lining in thermal insulation systems coverage. Within this objective we have characterized the thermomechanical properties - thermal conductivity, foam decomposition over temperature, decomposition process kinetics, elastic modules of storage and loss, Tan Delta - and assessed its thermal behavior when applied as lining. The rigid polyurethane foam has been shown to thermomechanical compatible for used as heat insulator heat at temperatures below ambient, and temperatures above 100 oC. Results obtained proved the rigid polyurethane foam efficiency in the heat exchange.