The emergence of 6G wireless networks demands solutions that seamlessly integrate communication and sensing. This letter proposes a novel waveform design for joint sensing and communication (JSAC) systems, combining single-carrier interleaved frequency division multiplexing (SC-IFDM), a 5G communication candidate signal, with frequency modulated continuous wave (FMCW), widely used for sensing. The proposed waveform leverages the sparse nature of FMCW within SC-IFDM to achieve orthogonal integration in three steps: SC-IFDM symbols are allocated alongside the sparse FMCW, followed by the SC-IFDM transform into the time domain, and a cyclic prefix (CP) is applied in which phase shifts are introduced to the FMCW. Additionally, an enhanced channel estimation method is incorporated to boost system performance. Simulation results demonstrate the proposed waveform's ability to deliver high-resolution sensing and superior communication performance, surpassing traditional multicarrier designs.