Why a finish that lasts in Riyadh fails in Jubail
Corrosivity category, not geography, decides the finish. The Kingdom spans four categories, and most catalogue guidance assumes European exposure.
01One country, four categories
ISO 9223 sorts environments by corrosivity from C1 to CX. Inland Riyadh and Qassim sit around C3. The industrial belt near Jubail runs to C4. The Gulf and Red Sea coastlines are C5, and permanent splash zones are CX. Treating the Kingdom as a single specification environment is the root of a large share of premature envelope failures.
The practical consequence: an electro-zinc plated item that performs for years inland can show corrosion within a single season on a coastal facade. The item did not fail, it was specified for a different category.
02Where the category bites hardest
Exposed fixings on a facade are the clearest case: at C5 the answer is A4 / 316 stainless or a Class 4 coating, and nothing less. But the same logic runs through anodising thickness on profiles, plating class on MEP hangers in a rooftop plantroom, and grade selection on drainage grates in wash-down areas.
Where a facade or roofing warranty names a finish, that warranty governs and overrides the category default. Send the clause with the enquiry rather than the product code. It changes what we are allowed to supply.