Prescriptive vs. Work Area vs. Performance

[haard17]

The state I do most of my work in recently adopted the code cycle which cites the Existing Building Code rather than Chapter 34. This is generally new to me over the past year, and I'm looking to steamline a work-flow to identify the 'path of least resistance' for compliance based on project type (Prescriptive, Work Area, or Performance).

Here's what I've come up with to date, curious if anyone else has thoughts:


Existing Building Code:
301.3.1 Prescriptive compliance method.
Alterations, additions and changes of occupancy complying with Sections 302 through 309 and Chapter 5 of this code are to be considered in compliance with the provisions of this code.

506.1 Compliance.​

A change of occupancy of an existing building or space is permitted without conforming to all the requirements of this code, provided the proposed use is not more hazardous than the existing use, based on an analysis of life and fire risk. Such analysis is permitted to be based upon the provisions of Chapter 13 of this code. If the proposed use is more hazardous than the existing use, such building is to comply with the requirements of Chapters 3 through 12 and 14 through 33 of the building code or with Chapter 13 of this code.​

​

• Use PRESCRIPTIVE §301.3.1 for Addition or Alteration to an existing building where you are not changing occupancy.
• Change of Occupancy then requires an extensive building analysis in Chapter 13.

301.3.2 Work area compliance method.
Alterations, additions, and changes of occupancy complying with Sections 302 through 309 and the applicable requirements of Chapters 6 through 12 of this code are to be considered in compliance with the provisions of this code.

· Use WORK AREA 301.3.2 for Change in Occupancy from Higher Hazard life safety hazard to Lower Hazard occupancy (i.e from M to B).

·

301.3.3 Performance compliance method.
Alterations, additions, and changes of occupancy complying with Sections 302 through 309 and Chapter 13 of this code are to be considered in compliance with the provisions of this code.

• Use PERFORMANCE 301.3.3 where Changing Occupancy from Lower Hazard to Higher Hazard occupancy (S-2 to R-2)

Thanks!

 

[Yankee Chronicler]

There is NO way you can reduce this choice to a couple of paragraphs, as you have attempted to do. Each project is unique, and the "best" compliance method has to be evaluated based on the specific parameters of each project.

I can tell you that over the course of four years looking at innumerable alterations in existing buildings, the vast majority I saw were Level 2 alterations using the Work Area Method. This means the project encompasses less than 50% of the total floor area of the building.

Of all the architects and firms submitting to the department I worked for, only one ever used the Performance Method. They used it for two separate projects within the same huge 19th century mill complex -- and they got it wrong on the first try both times. They were able to correct it and still get passing scores, but the reality is that the Performance Method isn't a "gimme." It requires that the design professional understand each and every criterion that has to be addressed, and that they assign their point scores objectively and honestly. Doing a Performance Method analysis is work -- and there's no guarantee that after you put in all the work you'll get a passing score. If you don't get a passing score, you're then back to choosing between the Prescriptive Method and the Work Area Method.

Use PRESCRIPTIVE §301.3.1 for Addition or Alteration to an existing building where you are not changing occupancy.

The Prescriptive Method applies to alterations, not to additions. Additions must comply with the provisions of the IBC for new construction. From the 2021 IEBC: