Based on a dynamic frequency study, the thermal behavior of a wall consisting of a concrete slab contiguous to a panel of compressed rice straw is presented. The thermal behavior at the interface of the two materials is modeled by a thermal contact resistance. The insulating nature wall thus made is studied according the order magnitude of contact resistance: the perfect contact (Rc=0) extreme contact defects (Rc very high). The analysis of temperature and heat flow density curves show that the insulation effects are all the greater as the defects are important.