# Work Area, Aggregate Area, and Level 3 Alterations



## drubinoff (Dec 4, 2012)

Hi,

Here in Massachusetts, I am designing an addition to a small two-storey mixed-use building with a semi-finished basement.  The existing second floor will be gutted, the roof removed, and a third storey built.  The second storey will have a change of use.  There will likely be some reworking of stairs on the first floor.  Each storey has the same footprint, although the new third storey will be have setbacks.

I'm looking at the 2009 IEBC §405, where a Level 3 alteration applies where the work area exceeds 50% of the aggregate area of the building.

With the basement being a stock room for the first floor retail store, how do I decide whether to count that floor as being part of the overall building area?  No changes are planned for the basement.

Secondly, in tabulating the "aggregate area" of the building, should I be including the area of the proposed building?  I'm trying to understand "50%" of what, exactly.  Old area?  New area including the addition?

Thanks,

Derek


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## RLGA (Dec 4, 2012)

drubinoff:

Welcome to the board!  Thats's a good question, which has no black and white answer.  Per the IEBC, if you use the work area compliance method then, like you've indicated, you'll have to comply with the Chapter 10 requirements for additions, Chapter 9 requirements for the change of use, and Chapters 6, 7, and/or 8 for the alterations.

The IEBC does not define what the "area of the building" is in regard to a mixed renovation project such as yours.  Personally, I would err on the side of caution and use only the existing building area to determine the 50%.  This then leads to your other question about whether or not the basement is included.  For that, I would defer to the IBC for the definition of building area, which would include basements.  The exclusion of a basement in building area only applies to the total allowable area permitted, but is still a part of the building area.


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## mtlogcabin (Dec 4, 2012)

Yes Welcome to the forum

You state the is "No changes planned for the basement"

Did you look at the definitons?

ALTERATION. Any construction or renovation to an existing structure other than a repair or addition . Alterations are classified as Level 1, Level 2, and Level 3.

CHANGE OF OCCUPANCY. A change in the purpose or level of activity within a building that involves a change in application of the requirements of this code.

If there is no construction or renevations then the sq ft of the basement would not be included in the 50% building area determination. The previous use of the basement and the proposed may be a change of occupancy under the IEBC.

I wish they would call it something different such as Change Of Occupancy Activity


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## RLGA (Dec 4, 2012)

mtlogcabin:

I think we're on the same track, but each approached the question diferently.  Yes, the basement would not be included in the "work are" by definition, but it is part of the "building area."  So if the area of each story (including basement) is 5,000 sq. ft., and the work is limited to the second floor, then the "work area" is 1/3 of the building area.  If there is work on the first floor, too, and if that work exceeds 2,500 sq. ft., then more than 50% of the building area is reconfigured and the requirements for Level 3 are applicable.

I would not include the addition when calculating the building area for determining whether or not Level 3 alteration requirements are applicable.


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## brudgers (Dec 4, 2012)

There is a meaningful difference between changing the use of a building and changing the occupancy.

  This has a substantial impact on the scope of changes required by the Existing Building Code.


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## drubinoff (Dec 4, 2012)

Thank you for the welcome, and I very much appreciate your posts.  A little more research made the "50% area" irrelevant in MA anyway in my case, as the MA amendment to IEBC 2009 §405 points to IEBC §912.1.1.  Per IEBC §912.1.1.1, due to a change of occupancy classification of the second floor (from office to residential), and if we separate the occupancies above from the existing retail store below by a fire barrier having a fire-resistance per IBC requirement (IBC §7), only the area of the new occupancy classification needs to conform with IEBC §8 (“Level 3 alteration”).  So, my project seems to be Level 3 no matter what in MA.  Nonetheless, your posts above will no doubt be a helpful record for those in states without such amendment.

Best,

Derek


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