Metal Deck
Corrugated steel sheet that spans framing as a roof or floor base.
Quick Answer
Metal deck is corrugated, cold-formed steel sheet that spans between joists or beams to form a roof surface or a floor base for concrete. Types include roof deck, composite deck and form deck. Estimators take it off by square foot, separated by profile and gauge, with openings and laps handled explicitly.
The Full Picture
Metal deck is the thin steel skin that sits on top of beams or joists. Roof deck carries insulation and roofing. Composite floor deck has embossments so it bonds with a concrete topping and acts together with it, reinforcing the slab. Non-composite form deck acts only as formwork for the concrete. The Steel Deck Institute publishes the standards for design and installation and consolidated several earlier documents into ANSI/SDI standards.
Profiles differ in depth and rib shape. Roof deck is commonly named by type, such as wide rib (type B), intermediate rib (type F) and deep rib (type N). Composite floor deck is commonly in the 1.5 to 3 inch depth range. Thickness is stated by gauge, where a lower number is thicker steel, and the usual range for roof deck is commonly 22 gauge up to heavier. "Rectangular deck" is a name some specs and suppliers use for ordinary rectangular-rib deck, as opposed to specialty profiles such as acoustical or cellular deck, so confirm the exact profile in the plan note.
On the plans, deck is shown on the roof framing plan or floor framing plan as a note, such as "1.5" type B 20 ga, galvanized" or "3" composite deck, 18 ga," with attachment requirements such as welds or screws and side lap fasteners in the structural notes and Division 05 spec. The deck type and gauge can change between areas of one roof, so read the plan notes, not only the general ones. Deck accessories such as pour stops, closures, cant strips and girder fillers appear on details.
Takeoff unit is square foot (or square, 100 SF) by type and gauge. Measure to the framing lines, deduct openings the drawings show, and add allowances for laps and end cuts using your own or your supplier's method. Accessories are carried in linear feet or each, and fasteners, welds, and shear studs are priced separately. Estimators should also pay attention to what OSHA requires for openings, since openings must be decked over or covered, and cover materials and holes affect field labor.
Real Examples
Common Misconceptions
People assume: Deck is just a commodity measured by roof area.
Actually: Type, depth, gauge and finish vary across the building. Pricing at one gauge for the whole roof can understate the cost of heavier areas and openings.
People assume: Composite and non-composite deck are interchangeable.
Actually: Composite deck is designed to work with the slab and has embossments for that purpose; form deck is only formwork. Swapping them changes the structural design and requires engineer approval.
People assume: Deck takeoff includes the studs, welds and accessories.
Actually: Those are separate lines. Shear studs, welding, screws, closures and pour stops are usually counted or measured separately.
Does MeltPlan Solve This?
Partially — adjacentMeltPlan's takeoff pulls quantities from PDF plans, and US-based estimators review and adjust them, which covers measuring deck areas and openings from roof and floor framing plans. Gauge selection and pricing stay with your team.
Measure deck areas and deduct openings from the plans →Frequently Asked Questions
What is rectangular deck?
The name some specs and suppliers use for ordinary rectangular-rib steel deck, as distinct from specialty profiles like acoustical or cellular deck. Meanings vary, so check the plan note for the exact type and depth.
How is metal deck priced?
By the square foot or the square, separated by profile, depth, gauge and finish, plus accessories. Get current quotes, since prices vary by market and order size.
What does gauge mean on deck?
Gauge is a thickness designation. A lower gauge number is thicker steel, so 18 gauge is heavier than 22 gauge.
What is the difference between roof deck, composite deck and form deck?
Roof deck supports roofing and insulation, composite deck bonds with a concrete slab as part of the floor system, and form deck is formwork only.
Where is metal deck shown on drawings?
On roof and floor framing plans as notes, in structural general notes, in Division 05 specifications, and on details for edges, openings and accessories.