Snow Shape Factor Ca for 2006 ABC

[charliealphabravo]

I am checking the snow load on an industrial building addition. Both structures are basically PEMB warehouses with 1:12 gable roofs that join along the eave to form a long valley.
The ABC states that the Ca must be adjusted from 1.0 to some "other value" for this condition, due to valley accumulation, non-uniform load, drifting, etc, but I can't find any guidance for this. What would be the appropriate Ca for this? Can anyone tell me if the NBCC Guide has anything about this?

Also I don't see any explicit guidance in the ABC for snow drifting patterns comparable to ASCE 7. Any thoughts on this? Is this concept entirely encompassed by the Ca shape factor? There section on "Full & Partial Loading" requires that half the load for Ca=1.0 be applied to the roof to cause the most critical effect, but this doesn't help me with the case where Ca might be greater than 1.0 like in the case I am working with.

Thanks in advance.

 

[BAretired]

ABC = Alberta Building Code?

BA

 

[charliealphabravo]

yes sir

 

[BAretired]

If you are designing to the Alberta Building Code, you need the NBC User's Guide. Commentary G, Article 36 deals with this subject to some extent.

BA