# Type of slabs

**URL:** <https://community.blackspectacles.com/t/type-of-slabs/7673>\
**Category:** Programming & Analysis\
**Created:** [December 31, 2025, 1:01am UTC](https://community.blackspectacles.com/t/type-of-slabs/7673 "2025-12-31T01:01:52Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![elie](https://blackspectacles.com/uploads/images/14.png) [@elie](https://community.blackspectacles.com/u/elie)\
**Post date:** [December 31, 2025, 1:01am UTC](https://community.blackspectacles.com/t/type-of-slabs/7673/1 "2025-12-31T01:01:52Z")

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In the PA video under Section 4.6, “Structural Systems in PA,” specifically for site-cast concrete spans table, what is the difference between a one-way solid slab and a one-way Beam & Slab system?

I was reviewing _The Architect’s Studio Companion_ and noticed that both systems can include drop beams, which made the distinction unclear to me. How do these 2 systems differ, and does the One-way Beam & Slab system allow for longer spans compared to a one-way solid slab?

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**Author:** ![kiaragalicinao](https://yyz1.discourse-cdn.com/flex029/user_avatar/community.blackspectacles.com/kiaragalicinao/32/1607_2.png) [@kiaragalicinao](https://community.blackspectacles.com/u/kiaragalicinao)\
**Post date:** [January 2, 2026, 5:04pm UTC](https://community.blackspectacles.com/t/type-of-slabs/7673/2 "2026-01-02T17:04:03Z")

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Great question @elie! The key distinction isn’t whether beams _exist_, but what’s doing the primary spanning.

**One-way solid slab** is the broader category, while **one-way beam & slab** is often treated as a subtype/configuration (basically a one-way solid slab supported by a regular beam framing system).

- **One-way solid slab:** the _slab itself_ is the main spanning element. You may have beams or thickened bands at supports, but the slab is still doing most of the spanning work between major supports.

- **One-way beam & slab:** the _beams_ are the primary spanning members, and the slab mainly acts as a deck spanning between beams (load path: slab → beams → girders/columns). It’s often listed separately because the behavior and sizing logic are more beam-dominant.

Because beams are deeper and more efficient in bending than a slab alone, **one-way beam & slab systems generally allow longer spans** (and better deflection control) than a slab spanning directly between supports.

Hope this helps!

Kiara Galicinao, AIA, NCARB  
Product Coordinator  
**[Black Spectacles](https://www.blackspectacles.com/en-us/)**