Infrastructure development, especially in the field of construction material technology, one of them is mortar. The water content greatly determines the energy performance and durability of the mortar. Water can enter building materials or mortar through rain. Damage caused by moisture is common, especially in areas with high moisture content. To solve this problems, a hydrophobic or water-repellent mortar was created, one of which was by using a hydrophobic additive, namely CaCO3/PU. The purpose of this research was to determine the effect of the composition of CaCO3/PU on the surface contact angle and mortar strength. This research uses spray coating method. The hydrophobic layer was made with various compositions of 5%, 10% and 15% and the carbonation temperature used was 60°C using an oven. This research resulted in optimum contact angle at 15% PU variation of 120.8936° and optimum compressive strength of 187,68 kg/cm2 at 10% CaCO3 immersion.