Network based wireless sensing has become an important area of research and various new applications for remote sensing are expected to emerge. One of the promising applications is structural health monitoring of building or civil engineering structure and it often requires vibration measurement. For the vibration measurement via wireless network, time synchronization is indispensable. In this paper, we introduce a newly developed time synchronized wireless sensor network system. The system employs IEEE 802.11 standard based TSF counter and sends the measured data with the counter value. It enables consistency on common clock among different wireless nodes. We describe the accuracy evaluation by simulation studies when the size of nodes increased. The hardware and software specifications of the developed wireless sensing system are shown. The experiments were conducted in a three-story reinforced concrete building and results showed the system performs more than sufficiently.