Chloride salts deposited on building surfaces not only accelerate the degradation of historic coastal buildings and incur costly repairs, but also penetrate into building plaster mortars and corrode steel reinforcement, reducing the service life of modern coastal buildings. The unclear chloride-salt deposition and their spatial pattern on different building surfaces severely hinder targeted salt-resistant designs for coastal buildings. This paper adopted a non-destructive method based on flocked swabs to sample salts deposited on surfaces of typical buildings in the Zhujiang River Estuary of Guangzhou, China. These field investigations enabled the analysis of the effects of environmental and architectural factors on chloride-salt deposition. Our results showed that offshore distances, building elevations, and building layouts critically governed such deposition, whereas building ages exerted little influence. Specifically, chloride-salt deposition on building surfaces was positively correlated with not only offshore distances in the 500 m–500 m range, but also building elevations in the 10 m–100 m range under unobstructed conditions. Moreover, narrower spacings between the buildings promoted greater chloride-salt deposition on their surfaces. It is envisioned that our findings will provide valuable insights into salt-prevention designs for new buildings and salt-resistant maintenance strategies for old buildings.