The length of timber beams of restricted commercial lengths can be increased by carpenter splices, which requires a thorough characterization of the flexural performance of these beams. An experimental study was carried out addressing timber beams joined with Jupiter ray splices to identify the influence of height-to-length (h:l) ratios of the splices on the mechanical performance in terms of deflection and flexural capacity. Jupiter ray splices with height-to-length (h:l) ratios of 1:2, 1:3, 1:4, and 1:5 were manufactured using computer-aided design (CAD) and computer-assisted manufacturing (CAM). The flexural performance of the tested beams was characterized in terms of modulus of rupture (MOR), modulus of elasticity (MOE), inelastic stiffness (Kinelastic), mid-span deflection (δ), and shear modulus values, measured using a four-point bending test setup under pure bending. Results indicate that implementing these joints reduces the flexural performance compared to equivalent solid timber beams without carpenter splices. The ratio concerning solid beams varies in ranges of 12–24 %, 26–43 %, 57–71 %, and 21–35 % of the corresponding solid beams average MOR, MOE, δ, and Kinelastic values, respectively. Moreover, a high linear correlation was observed between the average values obtained at the bending tests with h:l ratios in this study. Finally, the predominant failure patterns are described, identifying the critical points of stress concentration. © 2024 Elsevier Ltd