Strained Si and SiGe technology is broadly utilized as a substrate engineering technique for microelectronics, yet the phenomena causing enhanced radiation damage in strained Si are poorly understood. In this study, Si/SiGe superlattice sample were grown by low temperature molecular beam epitaxy with a strained layer either buried inside Si or deposited on the surface. The samples were irradiated by 2 MeV He ions at room temperature and were characterized in-situ by multi-axial Rutherford backscattering channeling analysis to determine the relationship between point defect accumulation and strain relaxation. The studies show that damage build-up, which increase with increasing He fluence, is not accompanied by strain relaxation. Furthermore, a strained layer buried at a depth of 50 nm is more radiation tolerant than a strained layer directly deposited on the Si surface.  The present study suggests that the surface plays an important role in determining radiation stability of strained Si.