Types of Metal Deck Finishes

The finish of the steel coil used for metal decking is most commonly one of the below:

Non-Galvanized or "Cold Rolled" 

Uncoated steel, painted with primer. Metal deck primer is applied to provide provisional protection. Commonly grey/grey or grey/white.

Galvanized 

The zinc coating acts as the protective barrier between the steel and the environment. Typically deck specified as G-30,G-60 or G-90.

Galvanized Base & Primer Painted 

Galvanized (G-30,G-60, G-90) base coil with a special baked on enamel primer paint in grey/grey or grey/white .

Galvanized finish

Galvanized steel is one of the most common types of outdoor decking because it is durable, corrosion resistant, and long lasting. Zinc protects the steel by acting as a barrier between the steel and oxygen and moisture from outside environment. Galvanized finish offers the best protection against rusting while allowing for good adherence of spray fireproofing materials. Galvanized deck exposed to ordinary atmospheric conditions does not need to be field painted for structural purposes. Often times, painting galvanized deck is desired for aesthetic purposes. It’s important to note that proper steps are taken to ensure proper adhesion to galvanized coils if a primer is not applied at the factory. Various oils or chemicals used to prolong the life of the coil may impact paints ability to adhere properly.

Learn more about Galvanized Metal Decking

Galvanized G-30

1. G30 metal deck has 0.3 ounces of zinc per square foot.
2. Less common type of galvanized metal decking used in industrial & warehouse applications
3. Indoor applications with no corrosive exposure or low humidity

Galvanized G-60

1. G60 metal deck has 0.6 ounces of zinc per square foot.
2. Most common type of galvanized metal decking
3. Indoor applications with low to moderate corrosive exposure or low to mid humidity levels

Galvanized G-90

1. G90 metal deck has 0.9 ounces of zinc per square foot.
2. 2nd most common type of galvanized metal decking finish or coating
3. Outdoor applications with moderate to high corrosive exposure or mid to high humidity levels

Cold Rolled Coil or “Prime Painted”

Prime Ptd finish is our standard primer (gray or white) applied over clean bare (cold rolled) steel, which is compatible with many field applied finish paints. The primer should be considered a temporary and provisional coating and should not be considered a "finished coat". UL compliant primers are available by request when spray fireproofing is of concern. Therefore, uncoated steel with paint should only be considered a temporary coating not a finished product. A final coating is recommended as handling, transportation and jobsite conditions are expected to impact the quality of the finish.

Grey Top & Grey Bottom

Galvanized finish offers the best protection against rusting while allowing for good adherence of spray fireproofing materials.

Galvanized metal decking is created via hot dip galvanizing process, which consists of placing steel into an acid bath to remove the surface scale. After removing any surface rust by dipping the steel coil into an acidic solution, the metal is then immersed in a molten zinc bath, where the zinc bonds to the iron to form a protective coating. The coating also helps make the steel more malleable and easier to form.

Grey Top & White Bottom

Galvanized finish offers the best protection against rusting while allowing for good adherence of spray fireproofing materials.

Galvanized metal decking is created via hot dip galvanizing process, which consists of placing steel into an acid bath to remove the surface scale. After removing any surface rust by dipping the steel coil into an acidic solution, the metal is then immersed in a molten zinc bath, where the zinc bonds to the iron to form a protective coating. The coating also helps make the steel more malleable and easier to form.

Uncommon Metal Deck Finishes

Why Metals Corrode.  During the extraction of the metal from the ore and the following production of a metal-alloyed sheet, energy is absorbed by the metal, taking it to a higher energy state. After the metal sheet is produced at the steel mill, the natural order is for the metal to return to a lower energy state. Under normal conditions with no protective surface coatings, the metal will oxidize and form a metal oxide film at the surface of the sheet.

Phosphatized Painted

On rare occasion for composite floor deck – a uncoated steel sometimes referred to as Phos-painted maybe specified.  "Phos-painted" for a rare finish specification . This steel deck finish refers to floor deck which the top is left bare or non-galvanized and the bottom is prime painted. The top of the deck will be phosphatized black steel. The design intent is to allow the concrete to bond directly to phosphatized steel surface.

This deck is painted with primer on the bottom side, and either galvanized steel, bare steel on top. It is imperative that phos/painted composite deck do not have paint on top of the deck as the bonding action between concrete and steel will be adversely affected by painting the surface of a composite deck where it meets the slab. It should be noted that phosphatized steel deck should be expected to develop rust prior to placement of the concrete as there is no protective coating.

Uncoated / Bare Finish

Uncoated or are means that there is no coating at all on cold rolled steel. This application, often known as "black" steel should not be specified when prolonged exposure is expected.

Finish Paint

Finish Paint can be applied to the deck either prior to roll forming or post-manufacturing. Note that this is not very common for structural steel deck due to concerns of scratching the finish during installation, but it is used for siding applications. Almost any color is possible, but the order must be of adequate quantity to be economical.