Exterior tiling is exposed to more aggressive conditions than interior tiling. The effects of sun, wind, rain, and frost combine to shorten the life of an installation, by exposing it to a continuous onslaught of a number of mechanisms.
Common issues and queries you can face
Use polymer-modified cement-based adhesives
A cement-based adhesive must be used for exterior work. Whilst standard cement-based tile adhesives are suitable for exterior use, highly polymer-modified adhesives offer enhanced bond strength, reduced porosity and therefore better resistance to frost & greater resistance to movement (thermally induced movement is inevitable particularly for walls). Tiles recommended for exterior use will often be fully vitrified and these also require a higher specification for the adhesive.