Cross Laminated Timber (CLT) has been used as an alternative to reinforced concrete for about two decades, with an emphasis on walls, floors and roof slab application in low-rise and recently in multi-storey structures. This occurred because CLT is renewable and has a considerably lower carbon footprint than concrete. In addition, compared to other timber products, CLT shows enhanced stiffness and load-carrying characteristics. However, CLT as a lightweight floor can exhibit undesirable vibration serviceability performance and typically provides lower sound insulation than concrete floors - particularly in the low frequency range (below 200 Hz). Although the latter is more related to impact sound transmission, airborne sound transmission can be still an issue in lightweight floors. Thus, this paper investigates the prediction of low-frequency impact and airborne sound insulation for a CLT floor. Vibroacoustic finite element models of a simply supported CLT floor were developed in COMSOL and validated against impact and airborne laboratory measurements. Predictions are shown for two different FEM models, one using solid elements with material orientation and the other using shell elements with homogenised material properties.