Upgrading construction type of an existing high rise building

[Tim Mailloux]

A client has asked me to look into the requirements to upgrade the existing construction type of his building from type 2B to type 1A so he can convert the entire 20 story building from office space to residential apartments. The IEBC doesn’t cover changing construction type so my assumption is that we would have to treat this building like new construction in compliance with the IBC. Am I on the right track?

 

[cda]

How big is his checkbook?

 

[cda]

Sounds like a RLGA question

 

[Mr. Inspector]

I would require that they need to show that the building complies to chapter 6 of the IBC for 1A construction classification.

 

[RLGA]

I agree with Rick18071. You would need to show compliance with Chapter 6--most importantly, Tables 601 and 602.

Usually, Type IIB construction means they used some unprotected steel within the building or the building is entirely constructed of an unprotected steel frame structure. If this is a steel frame structure, then all structural steel will need to be exposed so the proper thickness of fireproofing can be applied.

If this is a concrete structure, you will need to make sure the proper concrete coverage is applied over the steel reinforcement for Type IA construction (roughly 1" to 2" depending on the type of concrete and type of structural member). This may require material analysis to determine the concrete mix used and either x-ray or GPR to see where the reinforcing is located in relation to the concrete surface (unless the construction documents specify the minimum required coverage and the B.O. accepts that).

One question that I have is--how did you get a high-rise building from Type IIB construction? The tallest a Type IIB building can be is 5 stories and 75 feet, the latter being measured to the roof. For determining a high-rise building, the 75-foot threshold is measured to the highest floor above the lowest level of fire vehicle access. Thus, to make a Type IIB building a high-rise building, one of the following conditions must exist:

• The roof of the building is an occupied roof and the average floor-to-floor height for the five stories is 15 feet.
• The lowest fire vehicle access is well below the grade plane (probably 15 feet or more).

However, something is not right. Group B occupancies in Types IIB, IIIB, and IV are allowed one story less than the height permitted for Group R-2 occupancies for the same construction type. Therefore, you should be able to change a Group B occupancy to a Group R-2 occupancy for Type IIB construction.

 

[Paul Sweet]

Unprotected to 3-hour is a huge jump. If it is steel-framed it might be necessary to strip it to the steel frame, spray-fireproof it, and install new cladding.

 

[steveray]

First...start in the IEBC for COU CH. 10.....then you will need to look at change to a higher hazard use 1012.whatever which will bring you back to IBC H&A....

Transitioning to remote so code cites are a little less easy right now...Not sure if you could convince the AHJ on IEBC prescriptive, but that AHJ may not really care....