The Anatomy Of Metal Deck

Also known as roof deck, non-composite floor deck, composite floor deck, metal deck, decking or just deck.  Steel deck is a cold-formed steel panel usually used as a structural platform to form a roof or floor. In order to understand exactly what is metal deck used for, you first need to understand a few basic principles of how metal deck works:

Metal Deck Profile Terms

Metal deck profiles can be broken down into several different components of the metal deck.

Metal Deck Terms

The cover width is from the midpoints of the furthest apart flanges on a sheet.

Metal Deck Cover Width

Embossments are used in composite deck to grab onto the poured concrete slabs.

Metal Deck Composite Terms

Side Lap Types

The overlapping of neighboring longitudinal edges steel deck. The steel deck panels must have the same profile to be able to overlap. Some shapes of steel deck profiles are not able to overlap.

Metal Deck Interlocking Side Lap
Metal Deck Lapped Seam
Metal Deck Nested Side Lap

Interlocking Side Lap

  • Also called button punch and a bayonet side lap
  • Horizontal return on "female" lip
  • Can be button punched, welded, or screwed

Interlocking Alternative

  • Also called button punch and a bayonet side lap
  • Can only be button punched
  • No horizontal return on female lip

Overlapping

  • Also called barge & foot or nestable
  • Can be welded or screwed

What Are Metal Deck Spans?

Triple Span Condition Example

What Are Metal Deck Spans?

All Span Conditions

  • Roof deck uses center to center dimensions for calculations.
  • Floor deck uses clear span or edge to edge of beam dimension for calculations.

1 or Single Span Condition

  • A single sheet of deck with 2 supports. Typically beams or joists.

2 or Double Span Condition

  • A single sheet of deck with 3 supports. Typically beams or joists.

3 or Triple Span Condition

  • A single sheet of deck with 4 supports. Typically beams or joists.

Specialty Deck Types

Cellular Metal Deck Diagram

Cellular Deck

Has plate shop welded to underside of deck. Also known as "electrical" deck. 

Vented Deck

Is used with form deck and lightweight insulating fills.

Cellular Acoustic Metal Deck Example
Acoustic Metal Deck Example

Acoustical Cellular Deck

Has perforated bottom plate and sound absorbing "mats".

Acoustical Deck

Has perforated webs and sound absorbing batts.