"B" Roof Deck vs "C" Floor Deck - For Floor Use

[Deutero]

I've specified "B" deck for roof applications. Throughout the years, for FLOOR applications, I've seen B-deck specified on various plans from other engineering firms and have had it requested by contractors, due to in-stock convenience I presume. Therefore, not seeing any "red-flags", I also have specified it for floor use, whether with concrete topping or simple 3/4" deck.

After consideration, I wonder why I do not specify "C" deck which is apparently fabricated for floor apps. Further investigation shows that the two deck in question are virtually identical with the exception that they are reversed in orientation, such that the section profiles, and thus the Sp and Sn are exact opposites. With the Sp and Sn being so negligibly close, (IMO), is there any reason to change what I am specifying?

 

[JAE]

Type B deck is intended for roof deck.

Type "C" deck - I think you are referring to Vulcraft's Conform deck which is a utility deck that can also be used as a form-deck for concrete slabs (non-composite).

I've never seen type B deck used for floors and I've never done so. This is not to say you can't...just that I haven't seen it used that way.

 

[lkjh345]

Deutero:

I would contact Vulcraft and ask them. There maybe something that makes Type B deck inapporiate for floors. The engineers at Vulcraft would know and usually are very happy to explain the sublties of deck and joist engineering.

 

[Taro]

B deck is OK to use for floors. It is not as commonly used for floors because it is not as efficient or economical as deeper sections. But I have used it on occasion on remodel/retrofit projects to match the existing floors.

Just make sure that you use floor deck if you are counting on composite action. The floor deck has mechanical deformations to produce the required bond with the concrete slab while the roof deck may not.

 

[miecz]

United Steel Deck used to have a page in their catalog with design information for inverted "B" deck slabs. I believe they were commonly used in the 1980s. It's not in thier current catalog.

 

[shepherd]

I've seen a lot of the inverted B deck in stair landings and wondered why they did it that way. I've always assumed it was just cheaper and more readily available for the small amount needed.