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Comparing 1.5” Metal Roof Decking Types: A, F, & B Deck
Kathy Midence

By: Kathy Midence on March 23rd, 2021

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Comparing 1.5” Metal Roof Decking Types: A, F, & B Deck

Metal Deck | B Deck | Roof Deck

Metal roof decking has been around for decades. If you’re looking for it, you will find it on older buildings as well as newer construction. However, the metal decking you will find on older buildings is unlikely to match the metal decking profiles on the market today.  

Over the years engineers have developed and/or modified different types of metal roof decking. This is done to try and improve what currently exists, or to create a newer improved profile type. 

The two depths that metal roof decking is currently available in are: 1.5” and 3”.

Within these two depths, there are different profiles (shapes) that the metal decking is manufactured into. The deeper 3” panel is typically stronger, however it is also more expensive. The 1.5” deep metal roof deck type is more economical and is a great example of how engineers have modified an existing panel to create newer improved versions. 

There are currently three variations of 1.5” metal roof decking, types: A Deck, F Deck, & B Deck. You will find these types throughout the United States. Some are easier to locate and acquire than others. This is because a couple of the variations are older and are being phased out since they don’t offer as many benefits as the more modern version. 

At Western Metal Deck we have been stocking and supplying metal decking for the past three decades. We currently only offer Type B Deck, which is the most modern version of 1.5” deep metal roof deck. On the West Coast, where we are located, we don’t see many requests for types A deck or F deck. However, seeing as how they have been around for a while and you may come across them on repair work, we will go over all three types.

If you are needing 1.5” metal roof decking and want to learn about the three different profiles, we will cover them in this article. We will cover:

  • What Is 1.5” Metal Roof Decking?
  • What Is Type A Metal Deck?
  • What Is Type F Metal Deck?
  • What Is Type B Metal Deck?
  • What Is The Main Difference Between 1.5” Metal Decking Types?
  • Which Type Of Metal Roof Deck Should I Use?

What Is 1.5” Metal Roof Decking?

Type 1.5” metal roof decking stands for metal roof decking that is 1.5” in depth. As mentioned earlier, there are three types of 1.5” metal roof decking available throughout the United States: Types A, F, & B.

These types are non composite, smooth metal roof decking panels. They are intended for use as a structural roof deck panel to support insulation. They are then covered up with built-up roofing. 


What Is Type A Metal Deck?

Type A metal roof deck aka Narrow Rib metal deck, is 1.5” deep. As the nickname implies, the ribs of this type of metal decking are narrow.

The spacing between ribs are approximately 1”. The amount will slightly vary between manufacturers, as they have their own version of A Deck. 

Of the current 1.5” metal roof decks, this profile is the oldest. It is mostly used on repair jobs. However, it has been modified over the years, meaning if you are doing repair work and replacing A deck the newer version may not nest right into the older version. 

Type A roof deck should only be used in repair patchwork, when needing to match the existing style. It should not be used in new construction as type B deck is more economical and a stronger product. Type A deck is also more difficult to purchase, as it is not made by many metal decking manufacturers. 


What Is Type F Metal Deck?


Type F metal roof deck is also recognized by the Steel Deck Institute as Intermediate Rib metal roof deck. This is another version of 1.5” deep metal roof deck developed after type A deck. The panel is 36” wide and the ribs are 6” on center.

The rib spacing is a littler wider at approximately 1 ⅞”. The exact dimensions will depend on the manufacturer, as each manufacturer has their own version of F deck with slightly different dimensions. 

This type of metal roof decking should only be used in repair or patch work as it is not as structurally strong as type B-deck. 


What Is Type B Metal Deck?

Type B metal roof deck is also recognized by the SDI as Wide Rib metal roof decking. This is the most modern of the three types of 1.5” metal roof decking. It’s also the most economical and widely used. The panel is 36” wide, and the ribs are 6” on center.

The spacing between ribs is approximately 2 ½”, making it wider than both types A & F deck. 

Type B deck is most commonly used as a roofing panel to support rigid board insulation and built-up roofing. It is also used as trash gates, roofing on canopies, as well as fencing and siding. 

Click here to learn more about B Deck


What Is The Main Difference Between 1.5” Deep Metal Roof Decking Types?

The main difference between the three different types of 1.5” deep metal roof decking is the spacing between ribs. Which is why they are also referred to as Narrow Rib (A), Intermediate Rib (F), and Wide Rib (B). 

When type A was developed it was meant to support the insulation, however the insulation developed back then wasn’t capable of spanning a big distance between ribs. It would cave in over time resulting in the built up roofing to cave in. So they developed a narrow rib panel to support the insulation. However, a narrow rib panel decreases the strength of the overall panel. 

Over time insulation was improved and a wider, stronger panel was developed which was type F. The spacing between the ribs was nearly double the distance than type A deck. 

As time passed more improvements were made and a wider stronger panel type B deck was developed. Type B deck is the most commonly used metal roof decking panel, due to its strength to weight ratio and it’s also the most economical. 

Types A & F deck have become increasingly phased out over the years. It should only be used when required on repair or patchwork. 


What Types Of Metal Roof Decking Should I Use?

There are different types of metal roof decking available. The type you use will be determined by the application, but in most cases the engineer will specify the type you will need to use on your construction project. 

As mentioned earlier, metal roof decking comes in two different depths: 1.5” and 3”. The distance between supports will typically determine which type of decking is needed. When distance between supports is longer, the 3” deep metal roof decking is usually specified. When the distance between supports is smaller the 1.5” deep type B deck is typically specified.  

The current versions of metal roof decking have different sidelap attachments which can add to the strength. They are also available in different gauges. A heavier gauge is stronger, but also more expensive. 

At Western Metal Deck, we have a large selection of metal roof decking in types 1.5” B and 3” N. We stock it in different gauges and in a galvanized finish. We can supply material for the same day or next day pick up. 

To learn more about metal roof decking check out:

Metal Roof Decking 1.5" Type B and 3" Type N



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About Kathy Midence

Kathy Midence has worked for Western Metal Deck since 2009. She has worked with each department to better understand all aspects of the metal decking, metal roofing and metal siding industry.