Rehab code and overbuilt building

[Fast_Edd1e]

Using Michigan Rehab code.

I have a building that will be going thru a partial change of use. Practically a gut for majority of it and change from Business to Assembly in part of it.

I'm not finding it, but do I need to use Chapter 5 of the regular building code to make sure im within the area allowances for the building construction type?
For example. I have a first floor of 42,730, two stories total. As an A-3 (museum) for type 3b fully sprinkled, im limted to 28500sf. And frontage increase only gets me to 31,200.

I have no problem separating into a mixed use Assembly and Business. But just having trouble finding the area that is requiring me to do that when using the rehab code. Since im being asked that question from the contractor.

 

[classicT]

Michigan Rehab Code (2015 IEBC)​

1012.5 Heights and Areas​

Hazard categories in regard to height and area shall be in accordance with Table 1012.5.

TABLE 1012.5
HEIGHTS AND AREAS HAZARD CATEGORIES​

RELATIVE HAZARD	OCCUPANCY CLASSIFICATIONS
1 (Highest Hazard)	H
2	A-1, A-2, A-3, A-4, I, R-1, R-2, R-4
3	E, F-1, S-1, M
4 (Lowest Hazard)	B, F-2, S-2, A-5, R-3, U

1012.5.1 Height and Area for Change to Higher Hazard Category​

When a change of occupancy classification is made to a higher hazard category as shown in Table 1012.5, heights and areas of buildings and structures shall comply with the requirements of Chapter 5 of the International Building Code for the new occupancy classification.

Exception: For high-rise buildings constructed in compliance with a previously issued permit, the type of construction reduction specified in Section 403.2.1 of the International Building Code is permitted. This shall include the reduction for columns. The high-rise building is required to be equipped throughout with an automatic sprinkler system in accordance with Section 903.3.1.1 of the International Building Code.​

 

[Fast_Edd1e]

Thank you. I can get it to work with perimeter increases for each area. But this gives me the commentary i need with the contractor.