Gauges for Metal Deck
Gauge alone won’t yield a deck quote. The minimum information needed for ordering metal deck is deck type, gauge, finish — similar to the make, model, color of a car. An EOR specifies gauge based on design; missing type or finish leaves unknowns. Contact us to clarify when only gauge is called out.
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Gauge determined by application: if deck carries concrete, slab depth + span dictate gauge as set by EOR
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Without concrete, deck likely roof profile—reference max-span charts
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Unsure? Call us to discuss profile and finish requirements when only gauge is known
The Deck profile depth adds capacity. Example: a 3″ deep deck profile is inherently stronger and can span farther than a 1.5″ deep deck. Gauge adds strength at added cost. The projects span requirement based on support spacing also guides deck selection.
Typical Metal Deck Gauges:
What is 22 Gauge Metal Deck?
Commonly a roof deck gauge, often used in double or triple span conditions
What is 20 Gauge Metal Deck?
Typical for roof decks and composite decks, often used in double or triple span conditions.
What is 18 Gauge Metal Deck?
Most common composite deck gauge; also used in long roof deck spans or single span conditions.
What is 16 Gauge Metal Deck?
Generally rare; 16ga is most commonly used only when spans or project dictate this requirement or single span conditions.
What Gauge Do I Need?
The (EOR) or Engineer of Record should be dictating the steel deck gauge requirement for the specific job requirements. However, typically the deck gauge will depends on the below factors:
- Load capacities and/Concrete slab capacities
- Span capabilities of the deck during or after construction
- Diaphragm shear values
The metal deck gauge is a unit of measurement that refers to the thickness of the steel. The higher the gauge number the thinner the steel. The lower the gauge number the thicker or heavier the steel is.
Example 1:
16 gauge is thicker, and therefore stronger & heavier than 22 gauge steel
Example 2:
22 gauge is thinner, and therefore lighter & weaker than 18 gauge steel
Metal Roof Deck Gauges
Below is a table of design thicknesses that are most commonly specified by EORs for metal roof decking.
Common Roof Deck Gauges | ||||||
| Type | Gauge | Thickness / (in.") | (lbs. / ft2) | FM Span | SDI Max 1 Span | SDI Max 2 Span |
| 1.5 B | 16 (ga) | .0598 | 3.35 | 9'-6" | 8'-10" | 10'-5" |
| 18 (ga) | .0474 | 2.65 | 7'-5" | 7'-9" | 9'-1" | |
| 20 (ga) | .0358 | 1.95 | 6'-6" | 6'-5" | 7'-6" | |
| 22 (ga) | .0295 | 1.65 | 6'-0" | 5'-9" | 6'-9" | |
| Type | Gauge | Thickness / (in.") | (lbs. / ft2) | FM Span | SDI Max 1 Span | SDI Max 2 Span |
| 3.0 N | 16 (ga) | .0598 | 4.15 | 16'-6" | 17'-11" | 20'-8" |
| 18 (ga) | .0474 | 3.25 | 14'-7" | 15'-3" | 18'-0" | |
| 20 (ga) | .0358 | 2.45 | 12'-3" | 12'-9" | 15'-0" | |
| 22 (ga) | .0295 | 2.05 | 10'-10" | 11'-2" | 13'-2" |
1. SDI Maximum recommended single span for roofs.
2. SDI Maximum recommended multi span for roofs.
3. FM Maximum spans for Factory Mutual Class 1 construction.
a. Refer to the FM Approval Guide and FM 1-29 for fastening requirements and span restrictions at perimeter.
Composite Deck Gauges
Below is a chart of thicknesses measured in inches for commonly used gauges for steel composite decking.
Common Composite Deck Gauges | |||
| Type | Gauge | Thickness / (in.") | (lbs. / ft2) |
| 1.5 Composite | 16 (ga) | .0598 | 3.35 |
| 18 (ga) | .0474 | 2.65 | |
| 20 (ga) | .0358 | 2.05 | |
| 22 (ga) | .0295 | 1.65 | |
| Type | Gauge | Thickness / (in.") | (lbs. / ft2) |
| 2.0 Composite | 16 (ga) | .0598 | 3.28 |
| 18 (ga) | .0474 | 2.52 | |
| 20 (ga) | .0358 | 1.90 | |
| 22 (ga) | .0295 | 1.64 |
| Type | Gauge | Thickness / (in.") | (lbs. / ft2) |
| 3.0 Composite | 16 (ga) | .0598 | 3.57 |
| 18 (ga) | .0474 | 2.85 | |
| 20 (ga) | .0358 | 2.15 | |
| 22 (ga) | .0295 | 1.78 |
Non-Composite Deck Gauges
Below is a chart of thicknesses measured in inches for commonly used gauges for steel form decking.
Common Form Deck Gauges | |||
| Type | Gauge | Thickness / (in.") | (lbs. / ft2) |
| 9/16 | 20 (ga) | .0598 | 1.90 |
| 22 (ga) | .0474 | 1.55 | |
| 24 (ga) | .0358 | 1.25 | |
| 26 (ga) | .0295 | 0.95 | |
| Type | Gauge | Thickness / (in.") | (lbs. / ft2) |
| 7/8 | 20 (ga) | .0598 | 1.91 |
| 22 (ga) | .0474 | 1.63 | |
| 24 (ga) | .0358 | 1.31 | |
| 26 (ga) | .0295 | 0.93 |
| Type | Gauge | Thickness / (in.") | (lbs. / ft2) |
| 1.0 | 20 (ga) | .0598 | 1.95 |
| 22 (ga) | .0474 | 1.65 | |
| 24 (ga) | .0358 | 1.31 | |
| 26 (ga) | .0295 | 0.93 |
| Type | Gauge | Thickness / (in.") | (lbs. / ft2) |
| 1 5/16 | 20 (ga) | .0598 | 1.59 |
| 22 (ga) | .0474 | 1.37 | |
| 24 (ga) | .0358 | 1.13 | |
| 26 (ga) | .0295 | 1.11 |
| Type | Gauge | Thickness / (in.") | (lbs. / ft2) |
| 1.5 | 16 (ga) | .0598 | 3.35 |
| 18 (ga) | .0474 | 2.65 | |
| 20 (ga) | .0358 | 2.05 | |
| 22 (ga) | .0295 | 1.65 |