This paper presents a new structural health monitoring (SHM) method using frequency-modulated continuous wave (FMCW) radar. The method was developed to circumvent issues with SHM methods’ need for displacement measurements, which can be difficult to obtain robustly through integrated accelerations, or through other displacement measurement methods. Instead, interstorey drift ratios were estimated through the direct measurement of interstorey displacement using FMCW radar. Simulation of this method using historical structural response data verified suitably accurate displacement measurements could be obtained using FMCW radar, and prompted the construction of a prototype system. Experimental validation of this prototype was carried out on a shake table. The precision of the system in terms of mean interstorey drift ratio was found to be 1.09 × 10−3 . These results are encouraging for the future deployment of this SHM approach.