What is Dovetail Deck? How Does it Work?
Dovetail decking is an emerging variety that is best used when looking for long spans between supports or working with shallow floor depths. Additionally, the ribs on dovetail deck are designed to offer the appearance of a finished ceiling. This makes it convenient to install HVAC, plumbing, lighting and electrical to its underside.
Metal roof decking is a key structural building component in commercial steel construction of flat roofs. Corrugated roof deck is used for constructing and supporting the roof insulation and membrane. Metal roof decking is laid and fastened to a support structure, and then can be filled with insulation and covered with water proofing layers. Roof metal deck can span greater distances than other roofing materials and it carry greater loads across wider spans than other building materials.
Dovetail FAQs:
Why is Dovetail Deck Used?
It's practical solution for larger spans due to its shallow floor depth and unique strength due to the profile of the deck. By allowing a shallower slab depth it can enable engineers and owners to build more total floors on a building. In addition, the profiles underside provides a finished look where metal deck may be left exposed.
How Far Can Dovetail Deck Span?
Dovetail decking is ideal for open spaces between supports. It's various profiles and gauges allow for spans between 10 and 25 feet. The gauge is determined by the EOR (engineer of record) and the EOR is responsible for specifying the dovetail deck that will meet their design criteria. The distance a profile can span is controlled by the gauge or thickness or the steel, the profile or shape of the product, the KSI of the steel coil.
What Are The Dimensions Of Dovetail Deck?
2.0" dovetail deck is designed with 4 flutes that are equally spaced 6" on center with a 2" profile depth. The taller 3.5" dovetail deck is designed with only 3 flutes that are equally spaced 8" on center with a 3.5" profile depth.
How Wide is Dovetail Decking?
Both the 2.0" deep and 3.5 Dovetail profiles are 24" cover. The width of dovetail profiles accounts for the overlap that is required and is often referred to as cover width.
Types of Dovetail Profiles
Dovetail profiles leverage the strength of steel and architectural design appeal of uniquely shaped dovetail profile to create architectural and structural efficiencies. One of the most versatile decking profiles, dovetail metal deck can be used in a variety of floor and roof deck applications and designs.
These dovetail roof profiles are can be rolled as both standard non-acoustical and acoustical roof decks. The acoustical roof decks reduce the NRC to help lower ambient noise with insulation inserted in the flutes of the decking..
The dovetail floor profiles are manufactured with embossments for a composite action and can additionally be outfitted as acoustical metal deck by use of a cavity where the acoustical insulation can be placed.
2.0" Deep Dovetail Profiles
Dovetail profiles are a structural product with an aesthetically pleasing look in exposed ceilings. Its unique profile allows for farther spans with shallower overall depths. This 2.0 dovetail decks can be designed into a roof system or a composite floor.
Roof Profiles
- Standard Roof Dovetail Profile
- No Acoustical perforations
- 2.0" Deep Profile
- Acoustical Perforations to be filled with sound absorbing insulation
- Common where sound absorption is critical, such as gyms, auditoriums, theaters, multi-family housing and more.
Floor Profiles
- Standard Roof Dovetail Profile
- No Acoustical perforations
- Standard Roof Dovetail Profile
- No Acoustical perforations
3.5" Deep Dovetail Profiles
3.5" Dovetail profiles are a designed for even further spans than it's 2" counterpart. The deeper profile allow for greater spans or the ability to carry more concrete in a composite slab design. 3.5" dovetail products can be found in exposed ceilings and many other applications.
Roof Profiles
- Standard Roof Dovetail Profile
- No Acoustical perforations
- 3.5" Deep Profile
- Acoustical Perforations to be filled with sound absorbing insulation
- Common where sound absorption is critical, such as gyms, auditoriums, theaters, multi-family housing and more.
Floor Profiles
- Standard Roof Dovetail Profile
- No Acoustical perforations
- Standard Roof Dovetail Profile
- No Acoustical perforations
Common Dovetail Gauges
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: 18ga B deck is thicker, and therefore stronger and thus heavier than 22ga B Deck.
Example 2: 22ga B decking is thinner, and therefore lighter and thus weaker than 20ga B Deck
What Gauge Roof Deck Do I Need?
The (EOR) or Engineer of Record should be dictating the steel roofing decking gauge for the specific project . However, typically the rood deck gauge will depend on the below factors calculated by the engineer of record:
- Load capacities and/Concrete slab capacities
- Span capabilities of the deck during or after construction
- Diaphragm shear values
Below is a table of design thicknesses that are most commonly specified by EORs for metal roof decking.
Dovetail Deck Gauges |
||
| Type | Gauge | Thickness / (in.") |
| 2.0 Dove (Non-Cellular) | 16 (ga) | .0598 |
| 18 (ga) | .0474 | |
| 20 (ga) | .0358 | |
| 22 (ga) | .0295 | |
| Type | Gauge | Thickness / (in.") |
| 3.5 Dove (Non-Cellular) | 16 (ga) | .0598 |
| 18 (ga) | .0474 | |
| 20 (ga) | .0358 | |
| 22 (ga) | n/a |
Why Does the Gauge of Dovetail Deck Matter?
As shown above, the gauge or how thick the steel is for any manufactured profile is the main driver for structural integrity but also the cost of metal decking. In laymen's terms, more steel costs more and therefore heavier the deck gauges are very likely to be more expensive. Inversely the opposite it true, a thinner deck gauge will likely reduce the cost of steel decking. Therefore it is important that the (EOR) is optimizing the steel deck design and specifying the correct gauge without over designing the steel deck.
Finally, if you are unsure of what gauge of metal deck is required or have questions it’s always appropriate to request the EOR to dictate this. While O’Donnell Metal Deck is capable of assisting design --- O'Donnell Metal is is not a structural engineering firm and we do not own liability for customer requests.
Dovetail Finishes
The finish of the material used for steel deck is most commonly one of the three options below. It's important to note that typically in new construction the finish is dictated by the engineer and/or spefications. Therefore this typically isn't an option, but a requirement for a subcontractor looking to order metal roof deck. Thus, be sure to check your roof deck specifications and bid documents before placing an order.
- Uncoated steel, that is painted with primer on both sides.
- Sometime referred to as Cold Rolled Painted
- Galvanized steel
- Typically G-30,G-60 or G-90
- Galvanized steel that is painted with primer on one or both sides.
- Galv (G-30,G-60, G-90) & Either GRY or WHT Primer
Metal deck primer is applied to provide provisional protection for short periods of exposure. 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.
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 galv 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.
Finishes are typically prime painted or galvanized and roof decks range in gage mostly from 22 to 16 at the heaviest.
| Roof Deck | Function | Finish | ASTM | Comment |
| Deck is not exposed to view, dry interior, non-corrosive environment | Cold Rolled, Primer Paint | A1008 | All Steel Deck shall be covered with a material sufficient insulating value to prevent condensation under normal occupancy conditions. Insulation shall be attached to the deck by adhesives or fasteners. Insulation material shall be protected from the elements at all times during the storage. See ASTM C1126-89 | |
| Deck is exposed to view; non-corrosive environment | Primer painted deck or G30 may also be adequate | A1008 or A653 | ||
| In moderately corrosive or high moisture atmospheres | A galvanized finish such as G-60 or G-90 coating | A653 | ||
| Highly corrosive or chemical atmospheres or where reactive materials could be in contact with steel deck | Contact us to discuss alternate options | n/a |
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