An experimental study on fire spread was conducted using a solid polyurethane block receiving heat feedback from adjacent walls. Near- wall and near-corner configurations were applied to investigate the heat feedback effects from wall depending on the separation distance between polyurethane block and walls. Oxygen consumption method was used to measure the heat release rate (HRR). Flame spread rate was measured by video records of flame front for the each surface. The results show that in the case of insulation walls made of ceramic fiber board walls, maximum HRR was increased up to 20% for the near-wall and 40% for the near-corner configuration, respectively, as compared with burning in open configuration. Maximum HRR was increased as separation distance is increased to a certain value. After reaching the peak value, maximum HRR was decreased as the separation distance is increased. The heat feedback effects could be confirmed through flame spread rate both top and vertical surfaces, but more clearly appears in vertical surfaces.