• Luis:

Yes, they are from table 506.2 under Occupancy B, Construction Type IIB (which I used for my example) for Sprinklered Multi-story building (SM) and NS is from the same table for a Non-Sprinklered building (NS).

• Yisroel,

In order, here are what I believe are the correct answers to your questions:

1) The Sa in your example above would be 3.  This is because it says "actual number of building stories above grade plane, not to exceed 3."  The exception where you can use 4, where buildings are equipped throughout in accordance with Section 903.3.1.2 applies to those buildings that are equipped with an NFPA 13R sprinkler system.  It is important to note this distinction.  This is a residential-type sprinkler system.  If you were to be presented with this on the ARE, the ARE would tell you which system your building is outfitted with.  Most commercial sprinkler systems are NFPA 13 systems, not 13R.  In the example of your office building, this would be the case.  Be careful here.

2) Stick with 57.8%.  If you did 58%, it likely would not be a problem, but you can't go wrong with using one decimal place.  I would offer as well that the ARE will likely tell you how to approach this.  I recall having a few questions where it told me how many decimal places to round to on various questions where decimals occurred.

3) This Aa calculation is for the entire building - not just one floor.

Hope that helps!

• Wow! David, right on target. Great clarification, thanks a million.

• Yisroel,

Where did you find this original question? Or is this something you made up to test yourself.

Thanks!

• I made it up myself.

• Where did you get the Values for At and NS?

Are they on the Table?

• Hi, I don't want to further confuse anybody, but my question is:

If 3 should be used, then the correct answer for Aa is 83,155 sf x 3 = 249,465 sf.

BUT, what if there is no frontage increase that this particular site can benefit from? Then, the total allowable building area would be :

69,000 sf x 4 stories = 276,000 sf., which is actually more than 249,465 with a frontage increase benefit.

It doesn't make sense to me that the total building area become less after the frontage increase factor.

• sorry question if A(t) per the chart is total allowable area factor per story.

then wouldn't A(a) be total allowable area per story??