IFC_5c.perimeter_curtain_wall_revised.ppt

Editor's Notes

• #2: Notes: This list represents the topics that we will cover in this presentation. Customize this if you modify or add topics.
• #4: Notes:
• #5: Notes: All of these incidents represent well known incidents of fire where improper safing or the lack of safing was specifically identified as a cause for the spread of the fire. One Meridian Plaza above should be discussed as an example of the liability aspects of not doing this work or doing it improperly. THIS BUILDING STOOD VACANT FOR YEARS AFTER THE FIRE AS PART OF THE EVIDENCE for the $350 million in law suits that were filed. MGM Grand Las Vegas: Many people are unfamiliar with the events shown above. Relate these incidents to the MGM Grand. Even though curtain wall safing was not specifically listed, improper firestopping of all types was. They’ll usually remember this fire.
• #6: Notes:
• #7: Notes: Why is sealing the joint so critical? During a fire, the heated gasses and the products of combustion naturally rise. This creates positive pressure at the ceiling line. Thus the fire will attack this area first! Where the fire starts away from this area, an improperly sealed joint becomes a path for smoke and toxic gasses to migrate throughout the building putting the occupants of higher floors at risk and potentially allowing expensive smoke damage to occur in otherwise unexposed areas. The improperly sealed or unsealed joint also becomes a venting path for the fire. This can draw the fire towards the safing slot and towards the vulnerable non-rated curtainwall.
• #8: Notes: In the worst case, compartmentation is breached and the fire is allowed to spread vertically through the safing slot.
• #9: Notes: As superheated gasses and the byproducts of combustion collect within the room, a flash over eventually ignites the entire room and the window glass will shatter allowing the flames to play out of the windows and up the exterior of the building. The shattered windows provide oxygen to the fire.
• #10: Notes: The purpose of the Perimeter Fire Barrier System is to make sure that the safing slot remains sealed for the full duration of the floors rating and to maximize the performance of the non-rated wall..
• #11: Notes:
• #12: All model codes generally address requirements in two specific areas… extending the rating of the floor to the exterior wall and the question of vertical separation of windows.
• #13: Extending the rating of the floor or sealing the safing slot is a mandatory requirement of all major codes.
• #14: One requirement has no exceptions and that is the requirement of extending the rating of the floor to the exterior wall. Sprinklers are not an exception to this rule. Firestopping of the safing slot is mandatory.
• #15: Let’s talk about leap frogging.
• #16: Fire breaking out one window and back in through the windows on the floor above is referred to as leap frogging. Leap Frogging CAN happen! If it can happen… Why bother to protect the slot? This is a question that we frequently hear.
• #17: Sprinkler advocates claim that fire is not a big issue in a properly sprinklered building. In fact, the codes contain exceptions to spacing requirements where sprinklers are used. Yes… Sprinklers are an exception but keep in mind… If Leap Frogging is a concern… Then the sprinklers have failed or have been ineffective at knocking down the fire! At any rate, whether the building is sprinklered or not, THE SAFING SLOT MUST BE SEALED!
• #18: Sprinkler advocates have been lobbying the codes to reduce safing requirements. They argue that in the event of a fire, the fire can simply go around the safing slot.
• #19: Leap Frogging CAN happen! And obviously it can occur faster and easier as the window spacing is reduced. But a well designed Perimeter Fire Barrier System still offers a number of important advantages…
• #20: Installing a properly designed Perimeter Fire barrier System maximizes the wall’s performance at any given window spacing. A lot depends on the severity of the fire. Experts argue both ways in regards to the severity of the ISMA test. Some think it is too severe. Others feel the opposite. No matter which way… We know that we can improve wall performance with properly designed and installed systems and we think that is the true intent of the codes.
• #21: It wouldn’t do much good to seal the safing slot if the wall simply failed around it. There are ways to extend the performance of the walls and our engineering and testing are helping to develop them! Structurally, the non-rated wall is the obvious weak link. However, we are finding that a well engineered system can afford added protection to the wall. For example… Adding steel reinforcements keeps the mineral wool spandrel insulation in place and in many cases, prevents mullions from melting out beyond the floor line. This keeps windows and spandrel panels intact longer. Proper location and protection of wall mounting brackets also helps to keep the wall in contact with the safing seal.
• #22: In summary… Proper sealing of the safing slot meets the code requirement in regards to extending the rating of the floor to the exterior wall. Sealing of the safing slot also contains the fire at least until the fire breaks out of the windows. Proper sealing also prevents the wall area from being attacked from both sides (internally and externally). These systems are engineered to provide protection of critical structural elements. The wall performs as well as it possibly could.
• #23: In most fires, smoke is the big killer. The spray membrane is simply a better and more reliable smoke sealing method than foil and caulk beads. Whether fire can leap frog through the glass or not… Maximizing protection should be the goal. Even 5 minutes in an emergency situation has the potential to save lives. We owe it to the occupants of buildings to give them as much time to safely evacuate as possible. Sprinklers can and do fail. Sometimes they are turned off for some reason. In an earth quake, water may simply be unavailable. Passive fire protection provides the back up and helps to save lives.
• #24: Using a Perimeter Fire Barrier System doesn’t really add to the cost. An argument can be made that this type of sealing method actually makes the building tighter by providing the continuous membrane as well as a more uniform and continuous insulation envelope.
• #25: Notes:
• #26: NOTES: The fire is ignited within the burn room. At 5 minutes, the exterior burner is ignited and begins to play up the exterior of the curtain wall assembly.
• #27: Notes: At this time, two laboratories are equipped Perimeter Fire barrier testing. The not-for-profit Underwriters Laboratories in Northbrook, Il and a private commercial laboratory named Omega Point located outside of San Antonio, Texas.
• #28: NOTES: The UL test utilizes the ISMA (Intermediate Multi-Story Apparatus) and is a hybrid method based upon ICBO acceptance criteria and UL2079. This test was developed as a method of testing the surface flammability of synthetic stucco (EIFS) walls. UL2079 is not appropriate for testing these applications because it is a test for joints occurring between TWO RATED SURFACES. The safing slot lies between a RATED FLOOR and a NON-RATED EXTERIOR WALL. UL2079 also exposes only one side of the assembly to the fire. The hybrid test attacks the assembly on two planes. Hence F-W-D (floor to wall, dynamic) systems are not appropriate.
• #29: NOTES: The INTEGRITY rating is comparable to the F rating in firestopping. This is the duration in hours that an assembly has been tested to resist the propagation of fire to the unexposed side. The INSULATION rating is comparable to the T rating in firestopping. This limits the temperature rise above the ambient starting point on the unexposed side of the joint to 325 degrees F. This is derived from ASTM E119 which is the test standard used to evaluate the fire resistance ratings of floors and walls themselves. Obviously, the fire cannot break through the upper story windows during the test. This would constitute a loss of compartmentation. The rating is established for the entire assembly including the floor, safing slot, and exterior wall system rather than just the safing slot alone.
• #30: The test is not completely representative of real life. Very few lab tests actually are. Most tests provide useful engineering information as well as good comparative data from one construction to another. The test does provide very good information on performance of the safing system as well as the protection scheme applied to the wall framing and attachments.
• #31: The test should be considered as BROADLY REPRESENTATIVE. The assembly is an intermediate scale using stories that are about 7 feet in height. The height and width of the assembly limit such things as spandrel width and spacing. Other details such as drop ceilings or certain types of inner walls could not be tested either.
• #32: NOTES: Here is an actual test assembly.
• #33: This is the interior view of the 2nd floor prior to the start of the test. The brown line at the base of the wall is the thermocouple bundle (TCs) used to measure the temperature rise on the interior surfaces. This rise is limited to 325 degrees above the ambient starting temperature. The pale blue area between the TCs and the foil faced insulation is the joint area sprayed with AS200.
• #34: At the start of the test the interior burner is ignited.
• #35: Five minutes after the interior burner is lit, the exterior burner is ignited.
• #36: In this slide, flames begin to play up the exterior of the wall.
• #37: At this point, damage to the wall’s aluminum framing structure is becoming obvious. The transom (horizontal framing member) directly over the burner has melted away leaving the light gauge steel perimeter angle that we installed to keep the mineral wool curtain in place.
• #39: At the end of the test as this picture shows… The framing has been severely damaged in the area right above the fire window. The transom (horizontal framing member) directly above the window has melted away. The support structure for the mineral wool insulation is intact however, and has kept the protective envelope in place.
• #40: Notice the damage to the mullions (vertical framing supports). This slide illustrates the value of mullion insulating covers. Without them, the fire would have burned through into the interior.
• #41: This interior photo taken after the test illustrates that the coating is intact. A slight gap is showing up against the spandrel insulation. This is the toughest area to protect and would be the failure point if the test were to continue. Having good stiffback support in this area has protected the gap and kept it closed for the full duration of the test.
• #42: The ISMA test is relatively new but already its impact is being felt. Construction methods and wall designs are changing. Let’s take a look and compare some of the newer methods to the older traditional ones.
• #44: So how do we protect the perimeter of the building to keep these failures from occurring and most importantly provide life safety? Remember we talked about mineral wool curtain wall insulation being able to withstand over 2,000 degrees for five hours? That is why perimeter fire containment systems are protected with mineral wool. When providing protection to the exterior wall, there are basic design principles that must be followed: 1. .First- Mechanically attach the cw insulation. This keeps the material in place during a fire when a lot of movement is taking place. Plus it keeps the material in place over the life of the installation. You definitely don’t want the insulation to fall out during a fire and loose the protection that it was intended to provide.
• #45: This shows insulation mechanically attached to framing.
• #46: Protect the aluminum mullions. Why? Because we know that aluminum melts at 1220 degrees F and it happens as quickly as 9 minutes into a fire.
• #47: This shows mw mullion cover insulation mechanically fastened over the mullions to protect them from fire exposure.
• #48: Step 3, Compression-fit Safing Insulation between the face of the slab and exterior cw insulation to fill the gap. Safing can be installed in two directions. With the fibers in the vertical or horizontal direction as seen in this photo. The designs are very specific and you need to install the material according to a tested system.
• #49: This shows Safing Insulation compression fit in safe-off area.
• #50: Ensure that mineral wool orientation is installed per the listing
• #51: This model demonstrates both methods of installing the safing.
• #52: Step 4. Provide Backing/Reinforcement Member at Safing Line. Backer bars are required to maintain the seal created in the void when the safing is compression-fit from 25-50% between the slab edge and the vertical insulation. The force that the compressed safing creates will cause the spandrel insulation to bow, losing the integrity of the seal and creating an area where fire can breach through the void.
• #53: This shows backer bar placed behind cw insulation for support.
• #54: We’ve talked about fire containment, but what about smoke? Smoke is the leading cause of death in a fire.
• #55: For smoke containment, add a smoke barrier system.
• #56: A smoke sealant goes over the Safing Insulation.
• #57: This model shows two different smoke barrier methods. Listed designs are specific about the method of applying a smoke barrier.