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Fireblocking vs. Firestopping

October 27th, 2011

By Frank Bayer

You’ve just failed another rough inspection due to insufficient fireblocking….or is it firestopping. Confused on what is required around those holes through the top and bottom plates. (Didn’t I squirt enough of that red caulk around it?) How do I frame around bathtubs and soffitts? Hopefully I can answer these questions and demystify firestopping.


Let me start with the simplest explanation and begin with buildings covered by the International Residential Code(IRC). These include one and two family dwellings and townhouses under 3 stories. The only place firestop is mentioned in the IRC is Section 317-Dwelling Unit Separations. Through and membrane penetrations of fire-resistance-rated walls or floor assemblies need to be protected by an “approved” firestop system…. There are some exceptions which I will discuss later.

Since one family dwellings have no rated assemblies, we can leave these out. Two-family and townhouses have rated assemblies between the dwelling units. These are the only areas in IRC buildings which need firestopping. Again, I said I would start with the simple explanation, so I’ll leave a detailed explanation of firestopping to discussion about International Building Code buildings for later. That brings us to fireblocking.

We’ll start with the Code’s definition. “Building materials installed to resist the free passage of flame to other areas of the building through concealed spaces.” Section 602.8 lists 6 places where fireblocking in wood frame construction is required:

1. In concealed stud spaces vertically at floor and ceiling levels.

2. Connections between vertical and horizontal spaces (soffitts, coves, suspended ceilings).


3. Concealed spaces between stair stringers at top and bottom of run.

4. Openings around vents, pipes, ducts, cables at ceiling and floor levels.

5. Chimneys and fireplaces.

6. Cornices of two family dwelling at line of dwelling separation.

602.8.1 goes on to explain what materials can be used for fireblocking: 2 inch nominal lumber, ¾ plywood or OSB, ½ drywall and even unfaced fiberglass insulation. All these items and more can be used for fireblocking 4 of the 6 areas required to be fireblocked. For item #5 masonry chimneys and fireplaces we must go to chapter 10 where specific clearance dimensions(2” for chimneys, front and sides of fireplace, and 4” from back of fireplaces) from combustibles is required. The gap still must be fireblocked but it must be done with non-combustible materials .

Item 4-openings around vents, ducts…. is special and the most confusing. The fireblocking material around bottom and top plate penetrations must be …”approved material to resist the free passage of flame and products of combustion.” Let’s start with the definition (in the IRC) of approved. The 2006 edition of the Codes have changed this to a simple “Acceptable to the building official”. The easiest way to find out what to use is to ask the building official. When I asked an inspector of the jurisdiction I was moving to (and renovating the house I was moving in to) he gave me the standard “firecaulk” answer. Since he was near retirement and I did not want to delay my job, I did like any contractor would do and bought a couple of $16 tubes of 3M firecaulk at Home Depot and squirted them in the holes. But I must ask, why do we (inspectors) make contractors use expensive caulk around a duct or electrical penetration that will feasibly stay intact for a 2 or 3 hours in a fire, while the surrounding wood has burnt away?

When inspecting most IRC buildings and some IBC buildings, I allow tightly packed mineral wool or insulation, unfaced fiberglass insulation filling the cavity up to 16”, structolite(or similar products) and spray foam insulation as long as the penetration is not through a fire resistant rated assembly. At this point I can hear the grumbling from my fellow inspectors….spray foam insulation? Yes, the International Code Council approved a number of Dow Chemical products (mostly the Great Stuff family of foams) as an alternative fireblocking material in Type V construction (All wood framing). The conditions of use are contained in ICC’s evaluation service, Inc. report-NER-645. This report refers to the 2000 IBC and IRC, but since there has been no changes in fireblocking material requirements, this should still be a valid method of blocking.


Now I’ll turn our attention to firestopping and specifically firestopping of penetrations of rated assemblies (walls and floor/ceiling/roof). As in the IRC, the IBC requires penetrations to be protected by an approved firestop system which is installed as it was tested… To simplify, a product which was tested under certain conditions, was shown to maintain the rating of the assembly at the point of penetration.

Let’s say you have a 1hr wall separating a 2-family dwelling, your plumber installs the vent stack in this wall and a 1 ½ “pvc penetrates the membrane (one side) of the wall. This “membrane penetration” needs to be firestopped to maintain the 1-hr rating.



I’ve decided to use a Hilti system whose UL No. is W-L-2244. This means Hilti had this tested by Underwriters Laboratories. You‘ll see that there are a number of parameters which need to be met. First, this system is good for only a 1 or 2 hr gypsum wall. The U300 or U400 represents a series of “tested” wall assemblies which can be built with wood or metal studs (nominal 2 x 4 for wood or minimum 2 ½” for metal). The penetrating item can be up to a maximum of 2” PVC or cpvc plastic pipe. The closed system is that which usually carries fluids. Items 4 and 5 show the Hilti product used (FS-One), the amount (5/8” depth, ½” bead at point of contact) and the placement. Where there is an annular space, the caulk must be in it-between the drywall and the pipe. Under notes you will see that the maximum diameter of the opening is 3”, so if your plumber only owns a 6” hole saw, you’re out of luck with this system. Also, the annular space, the space between the PVC and the drywall can be from 0” (point of contact) to 5/8”. Again, if you have a piece of 1” pvc going through the wall and your plumber’s only hole saw was 3 inch, your annular space would be 1” if the pipe was centered. This system wouldn’t work.

So by this we can see that there are five important things to consider when deciding how to firestop a penetration.

1. What is the assembly you are penetrating made of (gypsum, wood, concrete)?

2. What is the item that is penetrating it (PVC, iron pipe, emt)?

3. What is the annular space (minimum and maximum)?

4. What is the size of the opening?

5. What is the hourly rating of the assembly?

Intumescent vs. flexible

Most manufacturers have a large number of products available. You may hear the term Intumescent. This type of caulk or putty expands when it is exposed to heat. It is typically used around combustible products like PVC and insulated pipe. Flexible sealants are typically used at rated joint (a whole other story) and penetrations by metal products-cast iron, emt, copper.

Passing Inspection

Most inspectors will ask for your “cut sheet” of the firestopping system used. If you have a number of different systems, a copy of all systems should be provided. If you don’t have the cut sheets available, my first question would be “How did you know how to install it”. The definitive wrong answer here is “The way we’ve been doing it for 20 yrs.” These cut sheets are your guide to correct installation. Firestopping decisions should be made before the first hole is cut (in the case of the plumber with the 6” hole saw)

Where do I obtain the cut sheets from?

There are a number of companies which manufacture firestopping (see our LINKS page). Each manufacturer has a catalog with their tested firestop systems. Which one to use would be based on access (who is your nearest supplier), cost and technical support. Most manufacturers have an 800 number where you can call for technical assistance. On larger jobs, most will send representatives to your sight and will also provide installation training. If your doing a lot of firestopping, it is worth the time to have a rep come in and train your employees (just make sure the employees who will actually be doing the installation are involved in the training).

What if I can’t find a system that meets my needs?

FS manufacturers can provide you with an engineering judgment. The manufacture’s engineers develop a system through test data of similar systems. Most Building departments require these be accepted by the architect/engineer of record and their department.

You say you never had to provide any specifications for your inspector. I’ve been known to approve a few metal pipes through a rated assembly when they have firecaulk around them without specs. For anything more complicated than that I require 2 inspections (initially) for the firestopping. First I check the packing material for required thickness, rate of compaction, and parameters of the system used. If the system calls for 1/2 thickness of caulk flush with the floor, the packing material must be recessed at least that amount. I will return once the sealant is in place. Performing dual inspections at the beginning of a large job ultimately saves time and money for both the contractor and the inspector.

The Exception

Both the IRC and IBC allow exceptions from a firestop system when the penetrant is steel, ferrous or copper pipes. The first is in concrete or masonry walls. The pipe has to be 6 inches or less and the total opening is no more than 144 sq inches. The annular space can be filled with grout, concrete or mortar as long as the space is filled for the full thickness of the wall or floor. The second exception allows you to use a material that has been prequalified to meet certain test standards (ASTM 119) for resisting passage of flames and hot gases.

Think Ahead

Hopefully, the most important point I have made is both fireblocking and firestopping should be considered long before you are closing in on rough inspection time. Whether it’s installing some OSB on a section of wall before framing a soffit, deciding which hole saw to use for vent stack or how the drywallers need to cut around openings in rated walls, forethought and buy-in by all trades will save time and money in the end.


The Code is a complex document which is open to interpretation. It is not unlikely to be in room with 5 inspectors and hear 5 different opinions. Get your local inspectors involved in the beginning and if you disagree let them know. Just make sure you’ve done your homework and can back up your opinion. Also, I am not trying to pick on plumbers. The six inch hole saw scenario was one I lived through(and can laugh at now).

While does not endorse any one firestopping manufacturer

click the following link for an informative video.


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Important Design Criteria for Single Family Dwellings

March 21st, 2010

Before the first shovelful of dirt is moved, there are important code required design criteria which must be met for single family dwellings.  Chapter 3 of the International Residential Code addresses these and I will review them in this article.  I will save snow, wind, live and dead loads for another time.


Light and Ventilation

Habitable rooms (space for living, eating, sleeping or cooking) are required to have glazing not less than 8 % of the floor area of that room. That is; a 10’ X 10’ room needs 8 sq. ft. of windows.  Of those 8 square feet, 4(or half) have to open to the outside. Of course there are exceptions.  First, the windows don’t need to open if adequate mechanical ventilation is supplied.  You don’t need the windows at all if you have mechanical ventilation and artificial light.  Finally, sunrooms and enclosed patios are allowed to be used for natural ventilation if 40% or more of the exterior walls of the sunroom are screened.   You must take into account that emergency egress requirements  in bedrooms is maintained(This will be discussed later).

Bathrooms are required to have a minimum 3 sq ft of windows, half of which need to open unless you have the required ventilation.

Interior stairs have to have lighting which illuminates the entire stairway located near each landing.  The controls for the lighting must be at every floor level when the stairs have six or more risers. Exterior stairs are required to have lighting near the top landing and both the top and bottom landing if it leads to a basement.  The light switches are to be inside the dwelling.

Minimum room areas and ceiling heights.

One room per house need to be at least 120 sq ft and other habitable rooms can be no less than 70 sq ft.  One exception to this is the kitchen.  The minimum dimension of any habitable room is seven feet. Hallways are required to be a minimum of 3 feet. “Habitable rooms, hallways, bathrooms, laundry rooms and basements have to have ceiling no lower than 7 feet.  There are a number of exceptions for beams and girder, unhabitable basements, and bathrooms.


“Every dwelling unit” has to have a toilet, sink and tub or shower. They also need a kitchen with a sink, and water and sewage disposal.  Kitchen sinks, lavatories, bathtubs, showers, bidets, laundry tubs and washing machine outlets must have cold and hot water.

Shower and tub areas have to be made of a non-absorbent surface at least 6 feet from the floor. Water resistant drywall is no longer allowed to be used in tiled shower or tub areas (2006 IRC and IBC).


The requirements for glazing address hazardous locations and the requirements for safety glazing which must be used in these locations.  For an excellent article which covers this subject in depth and gives you a historical and safety perspective about glazing go to the Code Check Web Site.  There are 11 areas considered by the IRC as hazardous locations.  There are also 10 exceptions to these locations.  Most importantly are doors, pool/sauna, hot tub, shower and tub enclosures/walls and fences,  large windows which are close to the ground, guardrails and glazing adjacent to stairways and ramps.  Section 308.4 of the 2006 IRC covers these locations along with the exceptions.  Skylights and greenhouse glass requirements are also covered.


A separation between the dwelling and a garage is a subject full of misconceptions.  “It’s a firewall….it has to have two layers of 5/8 gyp board on the garage side…., the door has to be a fire door with a closer are popular fallacies.   I can only speak for the last 20 years of CABO and BOCA requirements for separations,  but none of these have ever been required.  Here is what is required by the IRC 2006:

  1. You can’t have an opening into a garage from a bedroom.
  2. If you have duct work penetrating into the garage, it has to be made of a minimum of 26 ga sheet metal and cannot open into the garage.
  3. Other penetrations of the separation wall must be fireblocked.
  4. The garage shall be separated from the dwelling (including its attic) by ½ inch gyp board on the garage side (you could theoretically have open studs on the dwelling side).
  5. If there is a habitable room above the garage, the separation must be 5/8 gyp board (type X).
  6. The supporting structure of item 5 shall be protected by ½ gyp board.
  7. If there is a door in the separation wall, it must be either 1 3/8 inch solid wood, solid or honeycomb steel minimum 1 3/8 inch thick, or a 20-minute fire-rated door. (Wouldn’t a fire-rated door require a closer and positive latching?)

Emergency Escape and Rescue/Egress

A requirement for bedrooms in basement has now become a requirement for all basements with the exception of those under 200 square feet and used only for mechanical purposes.  An emergency window or door must be installed.  For basements with all sides partially or completely below grade, the emergency window is usually installed.  The sill height of such window cannot be more than 44 inches from the finished floor.  The minimum opening area has to be 5.7 square feet (820.8 square inches), with a minimum height of 24 inches and a minimum width of 20 inches. The well outside the window has to be at least 36 inches wide and 9 square feet in area. If a casement window is used, the well must accommodate it to fully open.  If the depth of the well is greater than 44 inches, a ladder or steps shall be installed.  The ladder or steps can impede into the required area of the well as long as the window can be fully opened. The rungs have to be 3 inches from the wall, 12 inches wide and not more than 18 inches

apart. Bars or grates can be placed over these openings but like the window itself-it must be operational from the inside without the use of a key or special knowledge.

Bedrooms must also have an opening, either a door or window meeting the above requirements.  If the bedroom or basement is at the grade level, the minimum opening is reduced to 5 square feet.

One exit door is required from the dwelling unit.  It has to be a minimum of 3’ wide and 80” high and should be side-hinged. No keyed locks are allowed on this door. There should be a landing (the width of the door and 36” in length) outside all exterior doors (there is an exception for non-egress doors).

Stairs, Handrails, Guard

Stairways and hallways shall be 36” wide minimum, with 80” of headroom at the stairs.  When a stair is enclosed, any walls, sofitts and the underside of the stairs have to be covered with ½ drywall.

Maximum stair rise is 7 ¾” and minimum tread depth is 10 inches.  These dimensions tend to vary by jurisdiction.  In 2003, The State of Michigan amended these to 8 ¼ and 9 inches.  The maximum deviation from the biggest rise to the smallest can be no more than 3/8 of an inch.  Landings are required at the top and bottom of each stairway (some exceptions) and a stair cannot exceed 12 feet in vertical rise.

Handrails are required on stairs exceeding three risers. Their height should be 34 to 38 inches measured perpendicular from the nosing to the top of the handrail.  They need to be terminated into the wall or into a newel post and a 1 ½ inch space (minimum) must be provided between the wall and the handrails.  Handrail grip size can either be circular between 1 ¼ and 2 inches in diameter, 4 to 6 ¼ inches perimeter dimension for non-circular(with a maximum cross section of 2 ¼ inches or on those with a perimeter dimension more than 6 ¼ inches it requires a finger recess on both sides of the profile.  This profile must meet certain dimensional requirements (Section R311.5.6.3).

Finally guards are required where a raised floor surface is more than 30” above the floor/grade below. They have to be 36” high (minimum).  Open stairs with a total vertical rise over 30” would also require a guard which would have to be 34” high (minimum).  Opening limitations for these guards are 4” and 4 3/8” for stair guards.  Please note that the forbidden “ladder effect’ was taken out of the IRC in 2003.

Smoke Alarms

Hard wired, interconnected smoke alarms are required in all sleeping rooms, outside the sleeping rooms, and on each story of the dwelling including the basement.  Exceptions are allowed for additions and renovations.

In Conclusion

I’ve only begun to scratch the surface of material covered in Chapter 3 of the International Residential Code. For those of you new to the Code, this is a great place to start and familiarize yourself with its requirements.  Those of you have been in the business for a while; this is a great chapter to frequently review because of the amount of information covered in it.  Unless otherwise noted, I have referenced the International Residential Code, 2006.

Articles, Residential Code

Construction Codes Explained

February 21st, 2010

With the Advent of the International Family of Codes, we have come closer than ever to having a uniform building code throughout the United States.  The International family of Codes came about when the three model code organizations Boca, ICCBO, SBC got together and worked towards developing a single building code.

A Little History

Hammurabi recieved a copy of the code from his Law Department

Hammurabi recieved a copy of the code from his Law Department

No story about codes would be complete if we didn’t talk about Hammurabi.  King of the Babylonian Empire, Hammurabi created the first known building code in 2200 B.C..  It was a little light on technical information, no span tables or egress requirements.  It simply stated that if a builder built a crappy house and it collapsed, whatever happened to the occupants would happen to the Builder.  If the homeowner’s son lost his legs in the collapse, then the builder’s son would have to have his legs removed.

The first codes in the U.S. were the results of massive fires in some of our larger cities. Chicago created a building code in 1875 after insurers threatened to cancel insurance for properties in that city. In 1915 Building Officials Conference of America (BOCA) was founded. They published the BOCA National Building Code.  This was used primarily in the east and Midwest.  In 1922 The Pacific Coast Building Code Conference (later the International Conference of Building Officials-ICBO) adopted the Uniform Building Code.  Finally, in 1940, the Southern Building Code Congress International (SBCCI) published the Standard Building Code. These were the three model codes that were used in the U.S. Today they are known as the legacy model code organizations.  In 1972 the Council of American Building Officials is formed and they produce the One and Two Family Dwelling Code.
In 1994 the three legacy codes created the International Code Council to develop a single set of model construction codes, publishing their first, The International Plumbing Code, in 1995.
One of the first orders of business for the three codes was to reorganize their codes to a single format.   This not only enabled the writers of the new International Codes to compare requirements of each code when creating the new code, it assisted users of the legacy codes to locate requirements in the new code easier.  An example is in the mid 90’s; all three codes’ Chapter on egress was changed to chapter 10.  When the International Code was published, users could easily find subjects although most found major changes to the subject matter.

What is a Code?

Building codes are regulations, when adopted by a municipality becomes law. Previously, most municipalities or states adopted one of the four model codes with amendments specific to their locale.
The purpose of building codes is to protect health, safety and welfare of the public by providing standards in construction.  I must stress that codes are minimum standards only.  The most important goal of codes is the protection of human life.  Property protection is also a concern of the code although life-safety always overrides property protection.  An example of this is slide bolts not being allowed on exit doors.  During the many inspections I’ve done of small commercial buildings, I have found rear exit doors secured with numerous “unapproved” locking devices.  I am told (by the owner) these are necessary to secure against break-ins. The code maintains life-safety over property protection and does not allow these locks. They must be removed.

Types of Codes

There are two types of codes-specification codes and performance codes. A specification code lists exactly what can be used.  For example Section 502.7.1 of the Residential Code requires Joist bridging to be …..”solid blocking, diagonal bridging, or a continuous 1-inch-by-3-inch strip nailed…..”  A performance code states a purpose that is intended and allows the designer to select the method of accomplishing this purpose. An example would be R801.2 “…..Ceiling construction shall be capable of accommodating all loads imposed…..”  The International Codes contain both types of codes.

Changes in the Code

The ICC publishes an updated set of codes every three years.  In the margin of the text you will see the occasional dark vertical line.  This means there has been a technical change in the code from the previous edition.  A small arrow indicates where an item has been deleted.  The State of Michigan, where I reside, makes state amendments to the ICC Codes.  The code is then published as The Michigan Building (Mechanical, plumbing etc.) Code.  In addition to the dark vertical lines and arrows, they use double vertical lines to indicate state changes to the code and an asterisk to denote International Code sections that were not adopted. While explaining how these changes are made to a code merits a whole other article, it is important to note that anyone can submit a code change, and hearings open to the public are held to discuss both sides of code changes.  Final say as to adopt or deny a change is left up to the “regulators”, those who enforce the code.


The scope of the International Residential Code and The International Building code is clearly defined.  Section 101.2 of the IRC defines it’s scope as construction, alteration……etc. of “detached, one- and two-family dwellings and townhouses not more than three stories above grade in height with a separate means of egress…”  The one and two family part is easy.  For townhouses we must look at its definition in chapter 2.  “….each unit extends from foundation to roof and with open spaces on at least two sides”.  Now we easily understand townhouses (remember separate means of egress and no more than 3 stories).  Let’s say we have a condominium complex where one building has units in the middle that meet the townhouse parameters.  On the ends of these units we have “stacked ranches”-different units on top of each other.  Even though we are providing a 2-hr horizontal separation (required 2-hr separation for townhouses in section R317.2), we are unable to use the IRC to build this building.  It must be reviewed under the IBC (bringing fire suppression into the picture).
Maybe not!! R317.2 considers each townhouse to be a separate building.  Could you secure permits for each townhouse and review it under the IRC and secure permits for the stacked ranches using the IBC for review.  I believe you can.  This is where the design professional should solicit the opinion of the local official in the predesign stages.

Referenced Standards

An interesting note on the IRC-it is an all inclusive document.  That is it not only contains the building requirements but also mechanical, electrical and plumbing codes.  Just read the 500 plus pages of the IRC and you’ll know all the requirements for building these dwellings.  Not really.  In chapter 43 of the IRC and in Ch 35 of the IBC we have a number of pages of “Referenced Standards”.  These standards become part of the code, sometimes partially or sometimes in their entirety, depending on how they are referenced.
An example of this would be “The Wood Frame Construction Manual for One-and Two-Family Dwellings” from American Forest and Paper Association (AF&PA).  This is reference in section R301.2.1.1 as one of the 5 methods of design for high wind/hurricane prone regions.  This document now becomes part of the code for these regions.

Free Advice

First and foremost, you should know which code the jurisdiction you are working in enforces.  You should have a copy of it also.  As far as understanding it, attending educational seminars is a great start but on any project I recommend you make contact with your local authority in the planning stages.  Contrary to common belief, most inspectors do not take pleasure in making you tear down what you have built.  Don’t wait until you’ve roughed-in 12 floors of a residential loft development before making contact with your inspector.


Access-Controlled Egress Doors

December 22nd, 2009

Nowadays security is a top priority for commercial properties due to terrorism, corporate espionage and threats to personal safety.  In the design phase of new buildings or renovations to tenant spaces, designers must take care that security measures meet the requirements of the building code.  I will talk specifically about Access-controlled egress doors (section 1008.1.3.4 of IBC 2006).

This section talks not only about entrance doors to a building, but any doors which are part of a means of egress.   In other words, if one has to go through a door to get out of the building, the following requirements must be met:

1)    A sensor must be installed on the egress side which detects an occupant approaching.  The door(s) must open either by a signal from or loss of power to the sensor.

2)    Loss of power to the access control system unlocks the door.

3)    Manual unlocking device must be placed on the egress side of the door.

4)    Activation of the building fire alarm (if provided) system shall unlock doors.

5)    Activation of building sprinkler or fire detection system (if provided) shall unlock doors.

6)    Entrance doors (not to be confused with entrance doors in a means of egress) in Groups A, B, E or M shall not be secured from the egress side when the building is opened to the general public.

We will look at three scenarios where security requires controlled access to a space.  First, we will look at the CEO’s office (figure 1). Her office is on the 32nd floor of a high rise building.  Security concerns require entry to the reception area leading to her office is gained only by keycard access. Placing the sensor and manual unlocking device on the reception side of the doors will not allow access to the office by an unwanted occupant(unless they know how to set off the fire alarm/ detection system, sprinkler system or cut power to that part of the building).  This scenario can easily comply with code requirements.

Figure 1

Figure 1

In the next two scenarios, meeting code requirements will defeat the purpose of providing the access control.  First we will look at locked doors in an elevator lobby (figure 2). In a multi-tenant high-rise, it is normal for tenants to restrict entry to their floor.  Locking stair doors from the stair side is allowed under certain conditions.  The only other access to the floor would be from the elevators.  If access control is installed at the elevator lobby, 2 of the code requirements would defeat the purpose of the locking devise.  Since the stairs (means of egress) are on the other side of the door (the tenant space), the sensor and the manual unlocking device have to be located in the elevator lobby.  The person you are trying to keep out just has to walk up to the sensor or manual unlocking device to get in.

Figure 2

Figure 2

Finally, we’ll look at a floor of a high rise building which has two different tenants (figure 3).  In this design, each tenant space has one stairway.  Two means of egress are required for each space so installing locking devices on doors leading to the other stair would require the sensor and manual unlocking device on the egress side,  again defeating the purpose of the locks altogether.

Figure 3

Figure 3

The solution?  Forethought.  By the time this issue is brought to the forefront, rerouting egress paths is impossible. A lot of the time, the controlled entry devices are installed by the owners without the knowledge of the general contractor and sometimes after final inspections.  I was once involved in a project that received a variance from the local authority.  They were not required to install the sensor or manual unlocking device (both of which would have defeated the security measure).  They did have a non-required sprinkler system in the building.  They didn’t, however, use the exception for pull station requirements (because of the sprinkler system) and placed pull stations throughout the building accessible to the public.

NOTE: Section 1008.1.4.4 of the 2009 IBC, access-controlled egress doors remains the same as 2006 except Group I-2 is added to groups A, B, E, M, R-1 and R-2 where access control is allowed.


Dryer Ducts in a Shaft-A Case Study

June 21st, 2009

Recently, I performed a preliminary inspection on an eight story building whose upper 5 floors were being converted into residential lofts. Framing was near completion on one of the upper floors and trade work had been started. One of the first things I look at any residential use in a multistory building are:

  1. Where does the bathroom exhaust go?
  2. Are there clothes dryers and if so where do they vent? And…
  3. Where does the heating and cooling come from?

I am looking to see if shaft requirements have been met.
On this occasion I found both the dryer duct and the bathroom exhaust entering into a single shaft.  The bathroom exhaust was protected by a fire damper at its penetration to the shaft.  The 4’ dryer duct was only firestopped at its penetration.  The shaft and ducts terminated at the 7th floor where an undampered 10” duct penetrated the shaft and terminated at an exterior wall of the building. The building was of type 1B construction and was fully sprinklered.  The design was reviewed under the 2003 Michigan Existing Building Code.

Dryer Ducts in a shaft-c3

Smoke and Fire Dampers Required

Section 716.5.3.1 is very specific in requiring both fire and smoke dampers where ducts penetrate a shaft. There are many exceptions but none that allow either penetrations to be installed without a smoke damper.  Although the building code does not address dryer ducts, I know that dryer ducts cannot be dampered in any way. This would create surfaces for lint to accumulate and create a fire hazard.

Catch 22

While the State of Michigan had not adopted the 2006 International Building Code at the time, it had adopted the 2006 International Mechanical Code. Under the ICC, chapter 6 of the Mechanical Code and chapter 7 of the Building code have been nearly identical for the section on “Ducts and Air Transfer Openings”.  The 2006 now allows an exception for smoke dampers for dryer ducts, kitchen and bathroom exhaust in Groups R and B (previously this exception had only been for bathroom exhausts in B uses only). This exception is allowed under the following conditions:

  1. The building is sprinkled with an NFPA13 system.
  2. The openings into the shafts are installed with steel subducts at least .019 inch thick.
  3. The subducts must extend at least 22 inches vertically into the shaft.
  4. An exhaust fan is installed at the top of the shaft.  This fan must continuously run and be connected to an approved “standby” power source.

With some modifications (subducts and exhaust fan at top of shaft) this installation can bypass both the fire and smoke dampers. (There is an exception for fire dampers in any use group if you install subducts-provided there is a continuous airflow upward to the outside.  The only foreseeable problem is the 10 inch duct at the upper floor.  Subducting would be not be practical because of constraints of air flow, lint accumulation and height. The shaft could be continued horizontally to the exterior wall of the building bypassing any fire/smoke damper requirements.  The final issue is the renovation was reviewed under 2003 IBC and these changes do not exist in that code. The builder would have to apply for administrative relief through the local Authority Having Jurisdiction.

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