Due to an increase in the usage of composites in the world of engineering in the past few decades, a rise has been observed in research related to the joining processes, especially, between composite parts. This thesis is mainly focused on Structural Health Monitoring (SHM) in composite single-lap joints (SLJ). ADEKIT A236/H6236 has been used as the polyurethane adhesive manufactured by SIKA (CH) company and the adherends were made of carbon fibre/epoxy prepreg woven, named XPREG XC130. The backface strain on SLJ was measured employing two different methods at the same time: the optic fibres (LUNA ODISI-B) and Digital Image Correlation (DIC).