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ASCE Hazard tool. 2024 IBC snow loads

H

Henchalwoog

Member
Joined
Nov 6, 2009
Messages
98
Utilizing the hazard tool online appears to provide a remarkable increase in roof snow loading (+10 #'s) - is this the case in locales that have adopted the 2024 codes? Have there been any pushback from designers / contractors?
 
I have been doing my due diligence with this and from what I can read it is a change from the allowable stress design to the load resistance factor design and the previous methods utilized a factor of 1.6 in the formulation of the snow loads and now they use a 1.0 so the end result is to be negligible but per our locale the 2015 IBC was 35 psf for Pg (we raised it from 30) with the typical final result of 24.5 actual per ASCE 7-10...now the hazard map indicates 45 which is the actual roof loading - so it is considerable
 
For my location there's a pretty significant difference:

ASCE7-16:
1764708172472.png

ASCE 7-22
1764708227410.png

I'm not an engineer, I don't know what this will translate to in real world designs, but a nearly 40% increase in the spectral accelerations for short periods seems significant. The change to 1-second period is less than 10%, but my understanding is that the short period number is what matters for short and "stiff" buildings which covers 99+% of what I'll ever see.

I'm sure it will be figured out and handled, but I'm not looking forward to multiple conversations that boil down to "Yes, this is new. Yes, this is required. Yes, I know it will add cost. Yes, I know you've been doing it this way for XX years. Yes, you should have known. No, I can't change the rules. No, neither can my boss. No, this doesn't mean I don't want more housing. No, this isn't personal. No, I'm not calling you names."
 
My state is going to adopt the 2024 I-Codes in 2026. The State Building Inspector has already let us know that we will be seeing significantly higher snow load factors all across the state.
 
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