Difference Between Galvanized Steel Decking vs. Primed Steel Decking

D-MAC Galvanized Steel Deck Q: What’s the difference between galvanized and prime painted steel deck? D-MAC Prime Painted Steel Deck
Bare Steel + Zinc Basic Components Bare Steel + Prime Deck Paint
G60 (0.6 oz/sf) or G90 (0.9 oz/sf) Standard Coating Thickness 0.3 mil dry film thickness single coat
Recommended for corrosive or high moisture environments within the finished structure.  (Highlycorrosive or chemical atmospheres may require stainless steel, which is available from D-MAC). Roof Deck Applications For roof deck applications, it is recommended for dry, non-corrosive interior environments in the finished structure.
Standard for floor form deck applications.  The slab dead load may be deducted from the concrete design, as the permanent form will always carry this load. Form Deck Applications May be used, but form must be designed as impermanent and therefore the slab dead load may not be deducted.
Standard for composite floor deck applications. Composite Floor Deck Applications Paint on the top side will interfere with shear bond and inhibit composite action.  Therefore, it should NOT be specified. Acceptable finishes include:  Bare steel top/painted bottom and galvanized top/galvanized and painted bottom.
If bare galvanized steel decking must be field painted, ensure that any mill treatment is removed before priming.  Instead, D-MAC recommends ordering galvanized steel decking that is prime-painted in the factory when field paint over galvanized steel decking is required. Preparation For Field Painting Apply field paint over a small area and test for adhesion before painting the entire area.
Field painting is possible, but deck must be cleaned and prepped extensively before the field primer and finish coats are applied.  To save field labor and potential adhesion issues, D-MAC recommends ordering galvanized steel decking that is prime-painted in the factory when field paint over galvanized deck is required. Field Painting Field Painting is recommended, especially where deck is exposed during service.
Shiny silver Standard Appearance Dull grey top and bottom
Shiny silver top, dull grey bottom Alternate Appearance Dull grey top, flat white bottom
Permanent Intended Life-span Impermanent and provisional
Exposed edges and scratches are protected from corrosion by zinc, BUT “wet storage stain” or “white rust” will develop if water is trapped inside the deck bundles. Common Corrosion When Stored in Ordinary Atmospheric  Conditions Exposed edges and scratches exhibit red rust.  Water that flows into the bundle will create rust stains inside the bundles. Spray painting ends and edges upon receipt may reduce rust staining.
Deck bundles should be stored off of the ground with one end elevated to provide drainage and covered with a well-ventilated waterproofing covering. Jobsite Storage Recommendations See recommendation for Galvanized deck.
More costly Cost The most economical steel deck finish
About 8% heavier than prime painted Weight About 7% lighter than galvanized
A653/A653M ASTM Specifications A1008/A1008M