I recently made a visit to a new, 3 story retail development. The purpose was to inspect two 2-hr fire-resistance rated duct shafts.  The shafts were continuous from the rooftop HVAC unit to the first floor, with openings onto all floors. Two previous inspections had failed for improper support of the shaft wall and improper framing for the fire/smoke dampers.

The building was reviewed as 2B construction and therefore the floors and columns required no rating. As the shaft walls (typical core board/metal stud construction) were built on the concrete floor, it didn’t meet the requirements for support.

Shaft walls must meet the requirements of a fire barrier and Section 706.5 of The 2006 International Building Code states “The supporting construction for fire barrier walls shall be protected to afford the required fire-resistance rating of the fire barrier supported…”  This means the horizontal and vertical steel which supports the concrete floor adjacent to the shaft must maintain the 2-hr rating. In this case, the columns and beams responsible for supporting the shaft wall were protected with spray on fireproofing.

Framing requirements for the fire/smoke dampers are specified by the damper manufacturer.  These may include doubling vertical framing members for larger dampers, specific methods for corner returns on the horizontal members and minimum and maximum clearances between the framing and the damper.

The installation of these shafts exceeded the minimum code requirements in two ways.  First, the shafts connected less than four stories.  IBC 2006 section 707.4 only requires a 1-hr rating.  Second, the shafts were not required at all.  Section 716.6.3 Nonfire-resistance-rated floor assemblies (remember Type 2B construction=no floor rating) only requires a fire damper installed at the floor line when connecting not more than three stories.

Now the design professional, building owner or building insurer might have required this higher level of protection (remember the Code is only a minimum requirement). The cost of shaft wall construction, additional protection of structural steel and fire/smoke dampers (including the electronics for the activation of the smoke dampers) should have been considered.

PLAN VIEW

Frank It Pays To Know $$$ Building Codes

As you may remember, in the 2006 edition of The IBC section 419 was a new addition which provided scoping requirements for horizontal and vertical separations between dwelling or sleeping units in I-1, R-1, R-2 and R-3 Occupancy classifications.  The one-hour separation requirement had always been in Chapter 7 of the IBC but now there was a directive to send you to Chapter 7 when checking on special requirements for the occupancies in question.

Now in 2009, the IBC has added that the same “between-unit” requirements be met between these occupancies and others.  Why is this important?  In some instances, the previous versions of the code would allow you to have no fire-resistance-rated separation between say a manager’s office and the apartment next to it.  Let me give you an example:

7000 sq ft, Type 3B Construction PLAN VIEW

Let’s take a 7000 sf building, with 5000 sf of 1^st floor area and 2000 sf on the second floor.  The second floor contains 2 apartments.  In 2006, section 419 sends you to 719(fire partitions) and 711(horizontal assemblies).  Both of these sections talk about ratings for walls or floors separating dwelling units (or sleeping units).  It did not require any separation between dwelling units and other occupancies other than the requirements for separated occupancies in Table 508.3. Now, we’ll say we are going to put in a BBQ restaurant in our building with solid fuel grilles.  The Code allows us to have non-separated occupancies if the building does not exceed the most restrictive building area and height limitations (from Table 503) for the occupancies in question.  We have an R-2 which is allowed to be 16,000 sf and 4 stories and an A2, which is allowed to be 9500 sf and 2 stories.  Since the A2 is the most restrictive and our building has not exceeded this, no separation is required under 2006 IBC.

ELEVATION

We could have an open ceiling with open floor joist between the restaurant and the apartments. (The requirements for the Sound Transmission Class requirements, oddly enough, have always required a “sound” separation (STC 50) between dwelling units and “public or other service areas”.)

All this changes in 2009.  Language has been added to require the 1-hr rating between dwelling or sleeping units and “other occupancies contiguous to them in the same building”. Now a minimum 1-hr rated floor ceiling assembly would be required between the restaurant and the apartments.

2009 IBC now requires at least a 1-hr horizontal separation between the lower level bar and the second floor apartments

As before, in Types 2B, 3B and 5B, these separations can be reduced to ½ hr in buildings equipped with an NFPA 13 sprinkler system. (Has anybody figured out a ½ hour wall yet?)

Frank Bayer

Frank New in 2009 Building Codes, Commercial, residential

All exits doors must open out (in the direction of egress).

We all know that.   We’ve either seen a television show or read a magazine article about the deadly fire at The Iroquois Theatre in Chicago back in 1903.  We’ve been told that one of the causes of the high death count (602 people, 575 which perished within the first 20 minutes) was the exit doors opened inward and in the panic, people were trampled at the doors, blocking the exits.  It was said that bodies were piled 7 ft high in front of the doors.

Well exit doors do not have to always open out.  The International Building Code allows an exit door to open inward if the occupant load is less than 50 persons.  As always, the occupant load is determined by calculation using table 1004.1.1.  (Since 2006, the IBC does allow the Building Official to approve a lesser load than those determined by calculation.)

This rule is especially useful in cases where a small commercial space is directly on the sidewalk.  The IBC does not allow doors or windows to “open or project into the public right-of-way”.

Door opens onto large sidewalk. Is this OK?

Note: While researching this article I wanted to define “public right-of way”.  Is it municipal property used for a sidewalk, street or alley?  Is it a sidewalk in front of a strip mall (private property)?  Is there a minimum width of a sidewalk?  I could not find a definition in the IBC even though it contains a chapter on encroachments into the public right-of-way.  Webster’s Dictionary also does not contain a definition.  I found a definition of “right-of-way” in the current City of Detroit Zoning Ordinance which stated “a strip of land occupied or intended to be occupied by a street, crosswalk, railroad, sanitary or storm sewer, electric transmission line…….”

Door on narrow sidewalk. Definitely not allowed.

Door opening onto walking area of private property.

My assumed definition has always been the municipally owned sidewalk, street or alley. I have always exempted strip malls from the door opening clause.

Frank Myths & Legends Building Codes, Commercial