ICC Existing Bldg Code 1

[vandede427]

My question is in regards to what information (specifically all the seismic design data listed in IBC 1603.1.5, or the wind info too) do you put in your general notes when doing modifications/alterations to an existing building.

There's the urban revitilization trend where owners buy an old warehouse or an old building and turn it into office space. Also, my office has done several jobs recently where churchs have bought vacant bldgs that were formerly big box retail or theaters and turned them into sanctuaries.

What I'm running into is that the modifications fall under the Alterations Level 2 category of the Existing Building Code (not increasing effective seismice weight by more than 5%). The ICC Existing Bldg code allows the existing lateral system to stay, but the current lateral load resisting system is no longer allowed under new IBC standards.

What do I say in my notes? Do I list the lateraly system as required by 1603.1.5, even though it's not allowed for new bldgs, but give some verbage that the existing code allows it for the existing one?

 

[Ron]

Yes...for liability purposes, put whatever information you used to develop your design and decisions.

Some level of info is required by the plans review department of your local building authority. That info must be provided. Beyond that, if there is any ambiguity between code provisions, state what provisions you used (not necessary "why" on the plans, but document "why" in your files).

 

[msquared48]

I agree with Ron. Document, Document, Document. Or, putting it another way, CYA.

Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask

 

[msucog]

also be aware that the seismic design parameters may have changed (possibly lowered) depending on the location, age of building, etc etc. it may even be advantageous to have someone look at whether the parameters need to be updated...and potentially save the owner some money. it could go the other way too. could also look at performing a site specific seismic assessment to possibly get up to a 20% reduction in the current mapped accelerations. just a few thoughts...

and yes, i'd document all substantial info that you know whether it may be "irrevelent" data or not. document exceptions too.

 

[vandede427]

Most of the old bldgs I referred to are unreinforced block walls. That falls under the Ordinary Plain Masonry Shear Walls category which is currently only allowed for design category A or B.

I did check what a soil class C would do for me if I did get the site specific study, but it didn't drop my design category. Plus, based on my knowledge of the area I don't think the soil is good enough to be a class C.

I think what I'll do is just list all the design info for the new work per IBC 1603, and then reference the ICC Existing Code for the existing bldg.

 

[SteelPE]

Just out of curiosity, which IBC code are you dealing with? I haven’t seen a “level of work” described in chapter 34 of the IBC and I am wondering if I am missing something.

Of course I haven’t really done much rehabilitation work before.

 

[vandede427]

The levels of alteration I was referring to come from a seperate ICC publication; International Existing Building Code. It takes it a little past IBC Chapter 34.

 

[SteelPE]

Interesting

I always thought the IBC was a little void when it came to the rehab of existing buildings. I guess I will have to get this one next time I have to do a rehab.

Thanks

 

[SteelPE]

Sorry for all the questions.

Is the IEBC code referred to anywhere in the IBC? I don’t see it listed in the referenced standards table and I am wondering how you actually get into this code?

 

[vandede427]

I agree with you on your question: how do you get into this particular code? I haven't found any verbage in Chapter 34 that dumps you into the IEBC if you surpass any criteria. I think the IEBC is more of an expanded commentary on IBC Chp 34.

The structural sections of this code are very minimal when compared to the entire code. Maybe one page total out of 400 pages of architectural egrees/occupancy/etc.

But it's important. To simplify

Level 1: no "real" structural modifications
Level 2: changes to the vertical system
Level 3: changes to the vertical and lateral system

 

[zdude]

For what it is worth, I recently put together a bid for an unreinforced masonry building rehab. I also found that the IEBC was not a referenced document in the IBC. I went through the juridiction that I would be working in nd found that they had not adopted the IEBC. Before completing my bid, I put in a call to the building official.

I believe that the seismic portion of the IEBC is basically the ASCE 41. Msucog is right, the design seismic event is a 2% in 50 year EQ.

To answer the original question, many of the notes I have on rehab projects like this are similar to the new project notes, But I make sure that the seismic notes clearly state the level of design event and the goal of the project (ie life safety or immediate occupancy).

FWIW, the building official was happy to see that something was being done with the structure and willing to accomodate using the equivalent of the IEBC.