The purpose of this research is to study the effect of a safety system provided for wall tile external building activity on productivity. The safety system composed of (1) stable scaffolding system (2) providing clean and not slip walkways on the scaffold (3) installation of handrails not less than 0.90 meters in height along sides of the scaffold (4) installing safety nets around outside perimeters of the scaffolding (5) indicating working area (6) installing stairs (7) providing protection for people who works below (8) providing tools and equipments for transporting material which are safe and ready for using and (9) providing personal protective equipment for workers. Cost of the safety system is 79318 baht for a wall tile area of 385 m2 or approximately 206 baht/m2. Productivity rates for prior and after the used of safety system are 1.91 and 1.85 m2/person/day respectively. The productivity declines for approximately 3 %. In addition our study found an impact of work is a height of Building the wall tile external productivity could decrease for 6 %.