# Allowable Area and Height

Aa = {At + [At X If] + [At x Is]}, where

Aa = Allowable area per story At = Area from Table 503 (above) If = Area increase factor due to frontage Is = Area increase factor due to sprinklers

##### Shortcut:

Let's break this formula into two sections:

1. [At X If] Frontage

2. [At x Is] Sprinklers

In **Section 1**, if there is a minimum of 30 feet around the entire perimeter of the building, then At X If = .75At

If not, then we can find the frontage factor by following this equation:

If = [length of the perimeter w/ min 30 feet around bldg / total perimeter length] - 0.25

In this example, If = [length in red / whole length] -.25 = .63

In **Section 2**, if the building is one-story and is sprinklered, then At x Is = 3At . If the building is multi-story and is sprinklered, then At x Is = 2At . If the building is not sprinklered, then At x Is = 1At .

##### Now we combine the 2 sections:

Example: Our building is two stories, sprinklered, and has a minimum of 30ft around the entire building. The construction type is IIB and the occupancy type is A-1. What is our allowable area?

Answer: Aa = 2.75At, where At = 8500, so Aa = 23,375 S.F.

# Determine Allowable Travel Distance

# Determine Required Egress Width

# Determine Occupant Load

**Occupant Load = Room's SF x Occupant Load Factor **(See below. Choose most stringent requirement from either IBC or NFPA)

[Example: Occupant Load of an office

SF= 200SF Occupant Load Factor = 100 (IBC, Business)

Occupant Load = 2]