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Which Roof Deck Is Right For Your Job?

Choosing the right type of roof deck for constructing low-slope roofs is important because the metal deck serves as the structural substrate. Steel roof deck installed directly over structural steel provides the solid surface for weatherproofing, insulation, and roofing materials.

Install metal roof deck on pitched or flat roofs for virtually all types of buildings. Strong, economical, lightweight, and easy to install, steel deck provides a structurally efficient product for roof systems.

Mezzanines and canopies constructed with metal roof deck exposed on the underside give additional visual texture. The corrugated steel profiles provide strength to the structure and an attractive ceiling for the inside.

Types of Roof Deck

                Type A Deck

Type A decking, also known as narrow rib decking, is 1-1/2” deep and 36” wide. Type A deck usually serves as a patch material for reroofing projects since more economical types of roof deck are now available.

When engineers first developed type A roof decking, they focused on the strength of the metal deck. However, it was only a secondary factor of concern. The primary objective was to maximize the width of the top flange. This would provide the maximum amount of support for the roofing insulation installed on top of the Type A deck.

Over time, roofing materials improved and steel deck manufacturers were able to reduce the width of the top flange. This reduction increased the efficiency of the section from Type A decking to Type F decking. And finally, from Type F deck to Type B deck.

Replacing Type A roof deck in a repair or re-roof application may present some challenges compared to replacing Type B deck. Since the existing, older style narrow rib deck may have a stiffening rib in the top flange, the supports may be spaced farther apart than “modern” Type A decking can span at the same gauge.

Additionally, the old profile of Type A deck is slightly different from the new profile; however, with a bit of encouragement, the two deck styles can be pounded together.

            Type F Deck

Next, engineers developed Type F-deck, also known as intermediate rib decking. Engineers widened the ribs to create a stronger metal roof platform. Eventually, steel deck manufacturers were able to further reduce the width of the top flange, resulting in Type B-deck.

At this point in time, F deck typically serves as a patch material for reroofs since more economical types of roof deck are now available. F-deck also measures 1-1/2” deep and 36” wide.

            Type B Deck

Currently, B deck has become the most popular metal deck for new roofs because of its strength/price ratio. Similar to its predecessors, type B decking, also known as wide rib deck, is 1-1/2” deep and 36” wide.

Other options for this workhorse of roof deck, B deck also comes in acoustical, cellular, or with both cellular and acoustical properties.

For span tables, contact Keystar.

            Type N Deck

N-deck provides a long span structural member. At 3” deep and 24” wide, Type N deck meets specifications for structures where the supporting members need to be placed as far apart as possible. This deep deck gives contractors the opportunity to increase the span while decreasing the gauge of the metal.

For span tables, contact Keystar.

An Illustration of Increased Strength

The progress of metal roof deck development is demonstrated by comparing the maximum spans for the four deck types with the same gauge. For example, notice the differences in these deck types’ span capabilities:

Deck type & gauge

Factory Mutual Maximum Spans (Ft-In)

A 20 5’ – 3”
F 20 5’ – 5”
B 20 6’ – 6”
N 20 13’ – 5”

Keystar: Roof Deck Supplier

For same day pick up or delivery for patching and repairs, Keystar stocks Type A Deck and Type F Deck in 20 gauge with a painted finish.

The wide variety of gauges and lengths of B-deck and N-deck stocked at Keystar guarantees that your construction material needs are met immediately. Painted or galvanized finishes available.

Keystar Industries has the inventory of steel decking to provide a timely and professional solution to your construction needs. We provide quality steel deck products with the goal to make your construction job easier.

For pricing and availability, call Keystar Industries today at 651-256-0008 or email [email protected].