This study assesses the reliability of active radio frequency identification devices (RFID) and Global Positioning System (GPS) sensors that, when combined with localization algorithms, can be used to locate tagged materials in construction sites. Specifically, this paper presents experiments used to assess the deviations from materials' actual positions to their estimated locations according to both centroid-based and proximity-based algorithms. The authors also analyze these deviations when considering only RFID signals with strengths stronger than certain threshold values. The results of this research also suggest that it is possible to infer relative distances from RFID-sensors to tagged-materials according to signal strength characteristics. Field experiments simulating typical construction conditions are used for testing this approach.