Steel finishes
Galvanized vs. primed vs. painted steel.
The structural notes usually set the finish. When they do not, or when two notes disagree, this is how the options compare. The bid states the finish for each member group.
| Finish | What it is | Corrosion protection | Look | Watch for |
|---|---|---|---|---|
| Hot-dip galvanized | Zinc coating bonded to the steel in a molten bath | Excellent; exterior and exposed steel | Silver, spangled; can be painted with prep | Longest lead time; piece length limited by the kettle |
| Shop primer | Rust-inhibiting primer applied in the shop | Fair; temporary protection until finish paint | Gray or red oxide | Needs field finish paint if exposed |
| Primer and paint | Primer plus finish coat in the specified color | Good with maintenance | Any color | Field welds and scrapes need touch-up |
| Galvanized and painted (duplex) | Galvanizing plus a paint system over it | Best long-term | Any color | Highest cost; used for exposed architectural steel |
| Bare / mill finish | No coating, for steel fully enclosed or fireproofed | None | Mill scale | Only where the engineer allows it |
Rules of thumb
How we usually recommend.
The engineer and architect have the final say, but these are the patterns we see most across Central Texas.
Exterior columns and canopies
Hot-dip galvanize. Add paint over it when the color matters.
Beams inside the house
Shop primer is usually enough once the steel is enclosed in drywall.
Exposed architectural steel
Duplex galvanize-and-paint with ground welds and clean connections.
Long pieces
Confirm the galvanizer's kettle length, or plan an engineer-approved splice.