What Is the Standard Depth of Type B Metal Decking?
Type B metal deck is 1.5 inches deep, with 36" coverage and ribs at 6" on center. The Florida Building Code does not prescribe a deck depth; it requires the roof to resist the design loads, and the engineer selects a profile and gauge that does. When spans exceed what 1.5" deck can carry, 3" Type N deck is the usual step up. We supply both.
How depth and gauge work together
At a fixed 1.5" depth, Type B gains capacity by going heavier in gauge: 22, 20, 18 or 16. Catalog construction spans grow from 8'-03" single span at 22 ga to 19'-03" at 16 ga, and from 10'-02" to 23'-08" over double or triple spans. These are construction-load spans; design spans come from the engineer and the full load tables.
Best practices on Florida roofs
- Size gauge and fastening for wind uplift, especially at edges and corners.
- Use multi-span sheets where the framing allows; they carry more construction load.
- Choose G90 for humid or coastal exposure when the spec calls for it.
- Use vented Type B under lightweight insulating concrete.
- Step up to 3" Type N when the support spacing is beyond Type B's range.
Get the right profile
Send your framing plans and we will confirm the profile and gauges in your takeoff and quote.
Type B construction spans, 200 lb load on 1 ft width (ANSI/SDI RD-2017, SD-2022)
| Gauge | Single span | Double or triple span | Cantilever |
|---|---|---|---|
| 22 | 8'-03" | 10'-02" | 2'-02" |
| 20 | 11'-00" | 13'-07" | 2'-09" |
| 18 | 14'-11" | 18'-05" | 3'-10" |
| 16 | 19'-03" | 23'-08" | 4'-10" |
Related Questions
Is Type B deck ever deeper than 1.5"?
No. Type B is the 1.5" wide rib profile. Deeper roof deck, such as 3" Type N with 24" coverage, is a different profile used for longer spans. The engineer chooses between them based on support spacing and loads. We supply both.
Why is it called wide rib?
Type B has a wider rib opening than narrow rib profiles, which gives more stiffness and load capacity at the same depth. It is one of the most common roof decks for commercial buildings. Its 36" coverage and 6" rib spacing are standard across the industry, which makes it easy to specify and detail.