The Exciting world of Construction - Podium Slab Foundation

Welcome back to The Exciting World of Construction. Podium Slab Foundation

Lesson Four. We trust what we walk on all the time, but do we know what’s really happening below our feet? UPSI does!

And we are going to share our knowledge with you. We’ll spend a few months going over terms such as footing, pier, grade beam, slab-on-grade, and podium slab.

That term, the Podium slab, has surfaced a lot lately with the SB-326 balcony inspections. (More about that at the end.) This has led to some interesting conversations (interesting to me anyway :) ) regarding building foundations.

So, let’s start with an oversimplified explanation of the podium slab.

Imagine a table with many legs. The legs are concrete and extend into the ground for some depth. The table top is also reinforced concrete. 

The table top is your podium slab. 

Those table legs are referred to commonly as piers. 

The piers may sit on a footing or may have been drilled very deep down to bedrock. The piers rely on friction, the footing, and/or the bedrock to not sink and rely on the surrounding soil and bedrock to not rotate over...

(think, that time as a kid you jumped up on your mom’s old end table and found yourself on the ground among a pile of antique firewood).

The pier cap is a thickened section of concrete between the pier and the slab where the rebar reinforcement from the pier reaching up, engages with the rebar reinforcement of the slab, reaching down.

There’s your podium slab.  On top of that podium slab will often be built many stories of retail, industrial, or residential space.

So why does this relate to balcony inspections?

The podium slab is strong enough to cantilever or hang over the edge of the piers. Often the architect will design a podium level balcony that is simply an extension of the podium slab. This balcony does extend out over open air but is an extension of the reinforced concrete podium slab. There is some discussion of whether those podium slab extensions should be inspected under SB-326. 

While a more in-depth discussion of what is required for SB-326 inspection is something for another conversation, it is generally accepted that those slabs do not fall under the requirements set forth in SB-326 for inspecting balconies.

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Next month we’ll work to cement your understanding of these foundational ideas and reinforce the concrete principles we’ve already laid out. Until then, give me a call if you have any general constructions questions or problems at your community that we can solve for you!