Electro-galvanised steel, or zintec, is the industry norm with stainless steel grades 316 or 304 available for those conditions that require the extra weather resistance properties they provide.
Galvanised steel is grade S275 mild steel sheet that has been galvanised through a process called electrolysis. This is applied at point of manufacture and is therefore part of the structural make-up of the material, as opposed to a post manufacturing additive, such as hot-dip galvanising.
When external prime paint is applied, galvanized steel provides high quality resistance to corrosion and rusting. SDI (Steel Door Institute) recommends use of the A Series specification of A40 or A60 for primer adhesion. The A60 specification is considered better than the A40 specification with respect to rust protection. However, SDI does not advocate the use of G-series due to its lower quality primer adhesion attributes.