• Welcome to The Building Code Forum

    Your premier resource for building code knowledge.

    This forum remains free to the public thanks to the generous support of our Sawhorse Members and Corporate Sponsors. Their contributions help keep this community thriving and accessible.

    Want enhanced access to expert discussions and exclusive features? Learn more about the benefits here.

    Ready to upgrade? Log in and upgrade now.

Unconventional Mixed-Use Podium Bldg Question

E

ETThompson

SAWHORSE
Joined
May 19, 2017
Messages
190
Location
Columbus, Ohio
Hi

We're exploring a potential project and discussing an approach I've never seen before, which is as follows (we are under 2017 Ohio Building Code, which follows the 2015 IBC). Not having seen this before makes me think there's a problem with it...or maybe it's just too expensive...?

We were discussing a 5 over 3 podium design, wherein the upper floors residential apartments of wood construction (Construction type to be determined, although I know it would limit our heigh and stories), and a Type IA podium below. However, we're discussing if the 3rd floor (the top floor of the podium) to be residential apartments. Since they are part of the podium, they'd be of Type IA construction. The bottom two floors of the podium would be an S-2 parking garage (open or closed is not determined).

The podium is tentatively 30' high to the top, so I understand that we'd be limited in overall height by the R-2 provisions (ie, with Constr. Type VA and full 13 sprinklers, would be 40' above podium or 70' above grade plane, Type VA could be 55' above podium, 85' above grade plane).

I have not seen residential floors below the podium level previously, but I'm not sure if there's something that's specifically preventing us from doing this...is there? The code says I can have any use (except H) and since the requirements for Type IA construction are high, I can't see that I'd really be limited in area or stories. Is there something I'm missing?

Also, would each parking level be required count as a story?

Thanks
 
Last edited by a moderator:
Did you mean “IIA” for the 85-foot height?

Type IA construction is not limited in height or area, so the podium can be as large as you can make it.

You’re correct about measuring of height in feet; whatever the height is of the podium is that much less Less available to you for the building above the horizontal separation. Each parking level would be considered a story.
 
No...Table 504.3 says 85' for Type IIIA sprinklered (same as IIA), unless I'm missing something. The intent is this is wood construction above the podium, so IIA would not fit that.

If this approach is permissible by the code, any thoughts as to why you don't see apartment floors "below the podium"? Or is it just that I haven't seen them...?
 
One normally hears about a 5 over 2 - is there anything telling me I can't do a 5 over 3? As long as I meet the requirements above?

Thanks
 
ETThompson1 said:
No...Table 504.3 says 85' for Type IIIA sprinklered (same as IIA), unless I'm missing something. The intent is this is wood construction above the podium, so IIA would not fit that.

If this approach is permissible by the code, any thoughts as to why you don't see apartment floors "below the podium"? Or is it just that I haven't seen them...?
Click to expand...
Okay, you just had VA twice, so I didn't know what the other construction type was meant to be.
 
ETThompson1 said:
One normally hears about a 5 over 2 - is there anything telling me I can't do a 5 over 3? As long as I meet the requirements above?

Thanks
Click to expand...
Prior to the 2015 IBC, you could only have one story of Type IA construction, but that was changed in the 2015 IBC to have no limit, as long as the height in feet for the building above the horizontal assembly does not exceed the permitted height as measured from the grade plane.
 
Thanks for the help. Has anyone encountered that structural requirement (post #5)? Does that limit things?

RLGA, thanks I see that I mis-typed.

Thanks
 
ETThompson1 said:
Thanks for the help. Has anyone encountered that structural requirement (post #5)? Does that limit things?

RLGA, thanks I see that I mis-typed.

Thanks
Click to expand...
I could not find any correlation between the structural discussion and the specific mention of "5-over-2 podium" construction. The article only states that the 2015 IBC "allows two stories of podium with five stories of wood framing above to meet the 85-foot maximum building height limitation and also meet the 65-foot SFRS height limit" (emphasis added)--it does not state that it limits it to two stories of podium and five stories of wood framing above.

According to ASCE 7, the 65-foot limitation is measured from the base, which, as the article points out, is located at the top of the lower portion building. At 85 feet for Type IIIA construction, if the building had a two-story podium at 20 feet, then the building above the podium could be 65 feet (the maximum structural height permitted for light wood frame construction per ASCE 7). At 65 feet, the five stories would provide an average 13-foot story height (floor-to-floor), which is quite generous for a residential building in my opinion. If the podium had three stories at 10 feet each, then the upper building portion would be limited to 55 feet. Thus, a five-story building would have an average 11-foot story height (more reasonable, but still a bit much for multi-family residential construction). Therefore, the building is still within the allowable height per the IBC and does not exceed the 65-foot structural height limitation of ASCE 7.

All that aside, a five-story wood frame building will still need to meet the requirements of IBC Section 2304.3.3 for shrinkage.
 
Last edited:
Good, thanks, that's what I took from it too. My boss was insistent you can't do 5 over 3, but I think I've convinced him (with your help!). Thanks!
 
You must log in or register to reply here.
Back
Top