How to Calculate Non-Separated Use w/H Occupancy

[Markmax33]

I was reading the building code today and trying to calculate the non-separated option for a building with multiple occupancies. The exception says, "H-2, H-3...shall be separated from all other occupancies in accordance with 508.4."

Which of the following are true:

1. This means that the non-separated use is calculated with the H-Occupancy floor area BUT the H-occupancy portions are separated.

2. This means that floors with H-occupancies cannot use non-separated use at all and must be calculated as separated. (This is what the code commentary book says!)

3. This means that the H-occupancies must be separated, but you the non-separated ratio is calculated upon the next most restrictive floor area and the ratio for the h-occupancy uses the h floor area.

A-2 occupancy B occupancy F-2 occupancy H-2 occupancy M occupancy

Aa = 13,395 ft2 Aa = 32,430 ft2 Aa = 32,430 ft2 Aa = 9,870 ft2 Aa = 17,625 ft2

Floor areas:

Floor A-2 Floor Area A-2 Ratio B Floor Area B Ratio F-2 Floor Area F-2 Ratio H-2 Floor Area H-2 Ratio M Floor Area M Ratio

3 31,321 ft2 2.338 3,210 ft2 0.24 3,210 ft2 0.24 8,000 ft2 0.597 1,532 ft2 0.114

2 1,351 ft2 0.101 35,135 ft2 2.623 3,513 ft2 0.262 6,555 ft2 0.489 35,135 ft2 2.623

1 3,456 ft2 0.258 80,000 ft2 5.972 531 ft2 0.04 533 ft2 0.04 1,531 ft2 0.114

Thanks! - Mark

 

[SAT]

A-2, B, F-2 and M can be one fire area (no-separated), each a fire area (separated) or a mixed of the two. The Group H-2 has to be separated (in its individual fire area)

Occupancy Group Allowable Area(from your post)

A-2 occupancy 13,395 sq ft

B occupancy 32,430 sq ft

F-2 occupancy 32,430 sq ft

M occupancy 17,625 sq ft

H-2 occupancy 9,870 sq ft (7,000 + 2,870)

H-2 can not exceed allowable area=9,870 sq feet

If you use non-separated (all occupancies except H-2) the most restrictive is Group A-2 so allowable area =13,395 sq ft

Actual area of mixed occupancy/13,395 + Actual Area of H-2 /9,870 ≤ 1

 

[Markmax33]

Thanks! I always thought it was that way but the code confused me.

 

[JBI]

I didn't understand any of what you two just posted... and I teach the stuff!

Markmax33, what was that mishmash of numbers and letters at the end of your post?

In order to go non-separated you simply apply most restrictive area for all the various uses.

If you max out the non-separated area allowance you will need to create a separate fire area for the H use.

Sum of the ratios for separated uses won't work as your non-separated side is already at a value of 1.

 

[AegisFPE]

The issue is the code does not permit all occupancies to exist together in nonseparated harmony. It specifically prohibits Group H from being a nonseparated occupancy (NSO).

The OP is seeking to have a mixed use building with Group H, but meeting the separated occupancy (SO) provision for the Group H area while the remaining mixed uses apply the nonseparated use provision.

The trick is, it's a little unclear how to mix and match SO and NSO, though there is a complimentary logical approach.

From the Commentary:

When one or more of the occupancies is a Group H-2, H-3, H-4 or H-5 high-hazard occupancy, the nonseparated occupancies option could not be applied for the Group H portions of the building (Exception 1). Any Group H occupancies would need to be separated as required by Section 508.4 for separated occupancies.

I read that the NSO can be applied to the remainder of the building, outside the Group H portions of the building. Therefore, the commentary does appear to support such an approach.We've sought to apply a similar weighted mix and match approach to address the MAQ of hazardous material storage in and out of cabinets within a common control area.