Perimeter Curtain Wall Fire Protection

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Perimeter Curtain Wall Fire Protection
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Topics for Discussion

• Brief history
• Dynamics of fire
• What do the codes say?
• How are they tested?
• How testing is affecting design

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Curtain Walls the Perimeter Joint
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A Brief History of Fires -Where Curtain Wall or
Safing Issues Have Been Cited
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Unsealed or Improperly sealed perimeter joints
cost lives and huge liability losses

• Summerland, Isle of Man, British Isles. Fire
  spread through safing slot. 50 people killed.
• Hilton Hotel, Las Vegas, NV. Fire spread from
  8th to 13th floor in 25 minutes. 8 fatalities.
• First Interstate Bank, Los Angeles, CA. Flames
  spread from 13th to 16th floor via perimeter
  joint. One death.
• One Meridian Plaza, Philadelphia, PA. Fire
  spread from 22nd to 30th floor through
  unprotected openings including slab edge.

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What are the dynamics of vertical spread in a
high-rise building?
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Fire begins on a lower floor, products of
combustion accumulate at ceiling level, and
positive pressure builds
Rated Floor Assembly and non-rated Curtain Wall
System
Vision Glass
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The fire follows the flow of air currents
If the void between the floor and curtain wall is
not properly sealed, flames will spread
vertically
and compartmentation is breached!
Vision Glass
Rated Floor Assembly and non-rated Curtain Wall
System
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Vision Glass
Fire attacks the curtain wall structure from both
sides causing a premature failure of the wall
structure and potentially the vision glass above!
Elevated temp. and pressure breaks lower vision
glass
Flames may erupt through the windows. Oxygen
fuels the fire.
Rated Floor Assembly and non-rated Curtain Wall
System
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A properly designed tested Perimeter Fire
Barrier System not only protects the perimeter
joint but critical wall framing and support
elements as well!
Firestop Coating or Sealant over mineral wool
safing
Properly installed supported mineral wool
spandrel insulation
Rated Floor Assembly and non-rated Curtain Wall
System
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How do the codes address the protection at the
perimeter?
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What do the codes say?

• All Model Codes call for the rating of the floor
  to extend to the exterior wall
• All Model Codes require minimum spandrel height
• All Model Codes allow spandrel height exceptions
  in certain sprinklered conditions

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Extending the Rated Floor to the Wall...
MANDATORY!
In rated construction, all floors are rated
The perimeter joint must be sealed with an
approved material or system that extends this
rating to the exterior wall surface
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Code Compliance
Meeting the Letter of the Law...
PROTECTING THE PERIMETER JOINT
1. Designing the wall to keep the firestop system
in place for the rated period of the floor is an
obvious necessity.
2. Designing and installing the firestop
correctly is the final step!
Firestopping the perimeter joint is mandatory.
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The Leap Frog Effect
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The Leap Frog effect
Fire may break out of a window and leap back to
the floor above! That being the case Why
bother to protect the perimeter???
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The Leap Frog effect
Sprinklers are an exception to window separation
requirements But not to requirements for
protection of safing slot!
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The Leap Frog effect
Sprinkler advocates are lobbying to reduce these
requirements After all The fire may jump around
the protection!
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The Leap Frog affect
The fact is, depending on window spacing and
other factors, the fire may jump! So what exactly
does a Perimeter Fire Barrier System do?
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The Perimeter Fire Barrier System
Slows the process down. Of course it depends on
window spacing and other construction factors As
well as the nature and severity of the fire
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The Perimeter Fire Barrier System
Along with sealing the slot area, a well
engineered system provides structural protection
and maximizes the integrity of the wall
system Keeping the wall and window system above
intact longer!
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The Perimeter Fire Barrier System

• Extends the rating of the floor to the wall.
• Forces the fire to exit the building in order to
  propagate to upper floors.
• Protects structural elements and helps prevent
  catastrophic failure of the spandrel system.
• Maximizes fire protection afforded by the
  non-rated wall.

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The Perimeter Fire Barrier System

• Prevents the migration of flame, hot gases and
  smoke through to floors above.
• Buys time for occupants to escape.
• Buys time for first responders to secure the
  building
• Provides additional protection in the event of a
  sprinkler or detection failure.

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The Perimeter Fire Barrier System
Provides energy savings through increased thermal
efficiencies throughout the life of the
building When considered this way, the life
safety benefits are free!
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How Are Perimeter Fire Barrier Systems Tested?
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ASTM E2307Standard Test Method for Determining
Fire Resistance of Perimeter Fire Barriers Using
Intermediate-Scale, Multi-Story Test Apparatus
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How Are Perimeter Fire Barrier Systems Tested?
Only two labs presently perform testing in
accordance with newly developed test methods

• Underwriters Laboratories Inc. Northbrook, IL
• Omega Point Laboratories Elmendorf, Texas

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UL OPL Testing

• Perimeter joint curtain wall test is performed
  in accordance with ASTM E2307
• Other labs, testing per UL 2079 alone, do not
  adequately capture the dynamics between a rated
  floor and a non-rated curtain wall assembly, the
  structural nature of curtain walls, and fire
  attacking at two planes
• Intermediate-Scale, Multi-Story Test Apparatus
  (ISMA) was developed for this application

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Testing Questions
Question What Test is used to Evaluate Perimeter
Fire Barrier Systems?
Answer ASTM E2307 using the Intermediate- Scale,
Multi-Story Test Apparatus (ISMA) is used to
determine

• Two ratings are provided per the ASTM E2307 test
• F-rating, in hours (resistance to fire spread)
• T-rating, in hours (temperature on non-fire
  side)
• UL provide two additional ratings using same test
  apparatus
• integrity rating insulation rating

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Testing Questions
Question How can this be representative of real
life?
Answer It cant! The test method indicates
whether 1. The safing method can last as long
as the floor. 2. The protection scheme can
adequately protect wall framing and attachments.
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Testing Questions
Question Then how representative is this test?
Answer It should be considered broadly
representative. Spandrel width, height, and
window spacing are limited because the test is
not full scale. Story height is approximately 7
feet. Wall framing methods, support, and the
safing slot itself are well represented and
provide excellent engineering data.
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Curtain Wall Test Assembly Pre-Burn
Transom above floor
Mineral wool insulation at spandrel area
Mechanical attachments supporting insulation
Transom below floor
Mullions
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Assembly Interior View Pre-Burn
Thermocouples measuring temperature rise
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Interior Burner Lit - Time 000
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Exterior Burner Lit - Time 005
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Flames Climbing Exterior Time 015
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Melting of Mullions Transoms Time 045
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Vision Glass Breaks Time 200
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Burner Off at 2 hours
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Post Test Close up Detail of Mullion and
Transom Damage
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Post Test Interior View
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ASTM E2307 Testing has Improved Perimeter Joint
Evaluation
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Vision Glass
Vertical Mullions
Transoms
Mechanical Attachment
Spandrel Panel
Firestop Coating
Stiffback Angle
Mullion Covers
Spandrel Insulation
Mineral Wool Safing
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Perimeter Fire Containment - Basic Design Criteria
1. Mechanically Attached Curtain Wall Insulation
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Perimeter Fire Containment - Basic Design Criteria
1. Mechanically Attached Curtain Wall Insulation
2. Protect Aluminum Mullions
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Mechanically Attached
1
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Perimeter Fire Containment - Basic Design Criteria
1. Mechanically Attached Curtain Wall Insulation
2. Protect Aluminum Mullions
3. Compression-Fit Safing Insulation -as required
per tested assembly Install Safing Impaling
Clips -as required per tested assembly
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Mechanically Attached
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Compression Fit Safing (Direction of Safing as
required per tested assembly) Safing Clips (as
required per tested assembly)
Protect Mullions
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2
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Compression Fit Safing (Direction of Safing as
required per tested assembly) Safing Clips (as
required per tested assembly)
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Perimeter Fire Containment - Basic Design Criteria
1. Mechanically Attached Curtain Wall Insulation
2. Protect Aluminum Mullions
3. Compression-fit Safing Insulation -as required
per tested assembly Install Safing Impaling
Clips -as required per tested assembly
4. Provide Backing/Reinforcement Member at
Safing Line
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Reinforcement Member
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Mechanically Attached
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Compression Fit Safing (Direction of Safing as
required per tested assembly) Safing Clips (as
required per tested assembly)
Protect Mullions
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2
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What about smoke?
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Perimeter Fire Containment - Basic Design Criteria
1. Mechanically Attached Curtain Wall Insulation
2. Protect Aluminum Mullions
3. Compression-fit Safing Insulation -as required
per tested assembly Install Safing Impaling
Clips -as required per tested assembly
4. Provide Backing/Reinforcement Member at
Safing Line
5. For Smoke Containment, Add Firestop Coating
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Reinforcement Member
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Firestop Coating
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Mechanically Attached
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Compression Fit Safing (Direction of Safing as
required per tested assembly) Safing Clips (as
required per tested assembly)
Protect Mullions
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2
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Firestop Coating
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Additional Design Questions
Question Why arent floor-to-wall (FW) systems
acceptable for curtain walls?
Answer Floor-to-wall systems test fire
resistance between a rated floor and rated wall
tested per ASTM E1966. CW systems are specific
perimeter tests between a rated floor and
non-rated curtain wall using the Intermediate
Scale Multi-story Apparatus (ISMA) per ASTM E2307.
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Additional Design Questions
Question Why are windows spaced so far apart? My
windows are closer together
Answer ASTM E2307 evaluates the interior passage
of fire and hot gases through the perimeter joint
only. Increasing the spandrel height reduces the
likelihood of the leap frog effect.
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Additional Design Questions
Question What is the function of the firestop
coating in these systems?
Answer The firestop coating performs several
important functions.
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Additional Design Questions
The Role of the Firestop Coating

• The most obvious role is as a smoke seal.
• Seals off the path of hot gasses. Makes the
  safing more effective.
• Glues everything together.

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Additional Design Questions
Question Are curtain wall joints static or
dynamic?
Answer This area is referred to as a slot. The
word joint suggests movement. Experts tend to
agree that a small amount of movement occurs
within the slot area. It is up to the design
professional to determine the level of movement
required for the project. Some wall designs are
subject to a small amount of vertical shear or
horizontal sway and some systems incorporate
these values.
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Additional Design Questions
Question What if our design isnt a perfect
match for a system?
Answer We strongly suggest specifying tested
systems. However, real world designs are seldom
a perfect match! Find a listing that is
reasonably close and contact the manufacturer for
an Engineering Judgment to match the design.
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Benefits of Specifying A Listed Perimeter Joint
System

• Completes the curtain wall package
• Applies pedigreed testing and competent
  engineering
• Assists the local AHJ
• Standardizes design and cost
• Limits liability
• Provides energy conservation from insulation value