Sprinkler Increase

If a building has sprinklers installed in accordance with Section 903.3.1.1 the following values of I_s are used:

Building areas limited by Table 503 shall be permitted to be increased due to frontage ( ) and sprinkler protection ( ) in accordance with the following:

Equation 5-1, Sect. 506.1

= Allowable building area per story (ft^2)

= Tabular building area per story in accordance with Table

503 (ft^2)

= Area increase factor due to frontage as calculated in

accordance with section 506.2

= Area increase factor due to sprinkler protection as

calculated in accordance with section 506.3

1. Eliminate all perimeters that are within 20 ft. of their front.

2. Add the remaining perimeters

1. Add the perimeter of the entire building.

1. Eliminate all perimeters that are within 20 ft. of their front.

2. Multiply the remaining perimeters by their respective fronts (use 30' for all fronts > 30')

(25')

(>30')

(>30')

(20')

Calculate

One Story

Building can increase by 300%

I_s=3

More than one story above grade

Building can increase by 200%

I_s=2

Exceptions:

Sprinkler increase is not permitted for H-1, H-2, and H-3 occupancies.

See sect. 506.3 for exception details

Let's look at an example to learn how to calculate A_a.

(>30')

We have determined the requested addition meets the code.

Allowable area (per floor): 30,090'

Tabular story limit: 2

Revised story limit (*Sect. 504.2): 3

Total allowable area: 30090' x 3 = 90270'

Calculated

Questions?

**2009 IBC - Section 506**

**Allowable Building Area**

Step 1:

Building Area Modifications

Calculate Frontage Increase

Allowable Building Area per Story

Plug the values of our previous equations into the allowable area equation:

Final Checklist

F = Building perimeter that fronts on a public way or open space having 20 feet (6090 mm) open minimum width.

F=15'+50'+55'+90'+70'=280'

Calculate F

P = Perimeter of the entire building.

P=15'+50'+55'+90'+70'+40'=320'

Calculate P

W = Width of public way or open space in accordance with section 506.2.1.

Calculate W

3. Add all the values up and divide by F

If the value in brackets is not >0, then I_f=0

Preparation

Calculate I_f

Calculate I_s

Calculate A_a

Decision

Table 503 in the IBC sets an allowable height and area for a building depending on its type of construction and group.

*Disclaimer: This presentation is only intended for educational purposes. All code related decisions need to follow the IBC adopted by your state or organization.

Example

A building owner has a 1 story building shown in fig. 1.

Construction Type: IIB

Group: A-1

Building area: 6900 ft^2

Sprinklered: Yes

Fig. 1

The owner would like to increase his building to a 3 story building with an area of 25,000 ft^2 per floor.

Need to find: F, P, and W

Let's calculate the increase due to frontage and sprinklers to determine if the addition is feasible.

Table 503 limitations on this building:

- 2 stories

- 8500 ft^2 per floor

For our example I_s=3

Notes:

*Sect. 504.2 allows for max building height increase and a max number of stories increased for some sprinklered buildings. See section for details.

Section 507 allows the increase of certain buildings to be virtually unlimited if they are surrounded and adjoined by public ways or yards not less than 60 feet in width. See section for details.

The value of (W/30) must be < or =1. See section 506.2.1 for exceptions.

Proposed

Proposed area (per floor): 25,000'

Proposed stories: 3