Construction Combustible Facades on High Rise Buildings July 2017

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1 RiskTopics Construction Combustible Facades on High Rise Buildings July 2017 Combustible elements used in the outer wall layers of high rise buildings have contributed to several large fire losses over recent years. These facade systems are often primarily decorative but can also contribute to the insulation and environmental performance of the building. Different types of facade systems can behave very differently in fire situations, ranging from non-combustible to highly combustible, resulting in rapid external fire spread. The challenge to building owners and risk managers is to identify those buildings most at risk and implement effective controls. Introduction Facade systems for high rise buildings range from simple decorative panels affixed to a concrete wall to complex multi layer systems incorporating thick insulation layers, vapor barriers, air gaps and membranes. Many of these systems have proven to be of concern, with the propensity to spread fire rapidly up the face of the building beyond the control of internal sprinkler systems. This mechanism of fire spread may not be fully considered by building codes and has led to a number of serious high rise losses, some including fatalities. Whenever possible, consider replacing facade systems containing combustible components with a noncombustible alternative or a system considered to be a Zurich Recognized Solution. When replacement is not an option, consider the guidance in this RiskTopic to help implement effective controls and reduce risk.

2 This document does not address low rise buildings (less than 7 stories or 23 meters (75.5 ft.) high). Also, for additional information on sandwich panels, metal faced plastic foam panels typically used in cool stores and food plants, see the RiskTopic title Construction Composite panels listed in the References. Discussion Facade system performance benefits Facade systems are often chosen to improve the insulation (and hence energy efficiency) of the wall assembly. These measures are increasingly being demanded by regulators and building owners. This has seen a major increase in the use of Exterior Insulation Finish Systems (EIFS) particularly in Europe, but now spreading across the world over the last 50 years. The other major driver for facade selection is decorative, with the trends to modern glass and metal finishes now well established and driving the uptake of products such as Aluminum Composite Panels (ACP). Types of Facades Figure 1 Selection of High Rise Buildings, Dubai. (Photo Source: Mark Middleton, Zurich) Exterior Insulation Finish Systems (EIFS) EIFS is a non-load-bearing, wall cladding system attached to the exterior wall substrate to improve thermal insulation, weather tightness or for aesthetic reasons. EIFS may be applied to a range of walls including masonry, concrete or (in the case of low rise construction) lightweight walls typically lined with a suitable substrate such as gypsum or cement board. The EIFS is typically attached with an adhesive (cementitious or acrylic based), mechanical fasteners or both. EIFS consists of a number of layers attached to the wall substrate, with the most basic EIFS consisting of an insulation board, an integrally reinforced mesh embedded in a base coat and a textured finish coat: Insulation: Typically foamed polymer. Most EIFS use expanded polystyrene (EPS); however other types of foamed polymers can be used including phenolic, polyisocyanurate (PIR) or polyurethane (PUR). The 2

3 insulation layer is typically 6.3 mm (1/4 ) to 100mm (4 ) thick. Thicker layers of 200mm (8 ) or higher are becoming more common, particularly in Europe. Non-combustible insulation materials such as stone wool can also be used. Reinforced mesh base coat: A reinforcing mesh, typically glass fiber, embedded in a base coat. Top coat finish: Typically a cement based polymer modified render, resistant to ignition and combustion, applied with a trowel or sometimes sprayed. Increasingly, a polymer only render with increased ignition hazards may be encountered. More recent EIFS installations may include a drainage or water management system to provide a way for moisture that may accumulate in the wall cavity to evacuate. In this case a water resistive barrier (membrane) is installed over the substrate with small drainage cavities created between the membrane and the foam when installed. Figure 2 Typical EIFS applications. Light weight framed construction (left). Masonry construction (right). (Image Source: Mark Middleton, Zurich) Metal Composite Material Cladding (MCM) Metal composite material claddings are typically thin section panels with metal skins bonded to an insulated core of plastic, rock wool or occasionally gypsum board. The wall panels can be formed into various shapes. Originally known as aluminum composite materials (ACM) or aluminum composite panels (ACP), a number of new skin materials have now been introduced such as zinc, copper, stainless steel and titanium. However, aluminum remains the predominant material, described further below. Aluminum Composite Panels (ACP) Typically ACP consists of two 0.5 mm (0.02 ) thick aluminum sheets bonded to a core material. The metal surface can be coated with a fluorocarbon surface coating in a range of different colors. The core material is typically polyethylene or a mineral filled core consisting of polyethylene with a percentage of mineral filler. A high ratio of mineral filling improves the fire performance. The thickness of the core material typically ranges from 2-5 mm ( ). These panels are significantly less expensive than solid metal panels at a thickness required to achieve the same flexural stiffness. 3

4 Figure 3 Illustration of Typical Metal Composite Cladding (Image Source: Mark Middleton, Zurich) Rain Screen Cladding Rain screen cladding is a type of facade construction usually installed to protect the structure of a building from the wind and rain and to provide improved thermal performance. It is sometimes referred to as a ventilated facade. Rain screen cladding can be applied during primary construction or as refurbishment to existing construction. Rain screen cladding typically includes the following elements: External wall / substrate: This may be solid masonry or concrete construction, or a lightweight framed wall. Insulation fixed to the exterior of the substrate: Insulation panels adhered or mechanically fastened to the substrate. The panels typically consist of mineral fiber based, foamed phenolic, polyisocyanurate (PIR), expanded polystyrene (EPS), or polyurethane (PUR). In some cases spray based insulation may be applied. Ventilation cavity and supporting brackets: A ventilation cavity of at least 25 mm is typically provided between the insulation and the rain screen external cladding. Aluminum or steel brackets which bridge across the air gap support the cladding. Rain screen cladding panel: Materials used can include metal composite cladding, high pressure laminates, timber products, metal sheeting, ceramic tiles, and cement board products. Gaps between edges of panels may be included in the cladding, often including significant openings at the top and bottom of the wall to promote ventilation and drainage though the cavity. Difference between sandwich panels and Aluminum Composite Panels Sandwich panels, also known as composite panels, insulated panels or white wall panels are widely used to clad the exterior of buildings or to separate spaces within buildings. They are formed by placing a core material between two facer sheets. There can be a range of insulation materials such as mineral wool and various foamed plastics. Aluminum Composite Panels are a specific type of composite panel as described above. Photos of a typical sandwich panel and an Aluminum Composite Panel are provided below. For further information on sandwich panels, see the Zurich RiskTopic Construction Composite Panels. 4

5 Figure 4 Example of sandwich (composite) panels with a low density foam plastic core (left). Example of Aluminum Composite Panel (ACP) with polyethylene core (right). (Image Source: Zurich) Other forms of exterior wall assemblies may be encountered. Additional information on other common exterior wall assemblies can be found in The Fire Protection Research Foundation Report Fire Hazards of Exterior Wall Assemblies Containing Combustible Components (see References). Recent fire events There have been a significant number of major fires involving combustible facades in recent years. Some of the more notable fires are discussed in the 2014 NFPA Research Foundation report tilted Fire Hazards of Exterior Wall Assemblies Containing Combustible Components (see References). Fire performance issues Fires on high rise buildings involving combustible facades can spread rapidly up the building, beyond the coverage of building fire protection systems and higher than can be reached by manual fire intervention. Experience shows that fire can spread to multiple floors, threatening lives and leading to large property losses and resultant business interruption. In one recent loss, fire jumped from one tower to another over a distance of around 30 m (100 ft.), highlighting the intensity of the fire and the contribution from burning debris. Figure 5 Recent fire events. Tamweel Tower (left), Ajman One (right) (Image Source: Peter Thompson, Zurich and Santosh Cletus, Zurich) 5

6 Combustible insulation The insulation within these facade systems is often combustible and can include expanded polystyrene foam, polyurethane (PUR) and polyisocyanurate (PIR) foams, commonly found in EIFS; or a polyethylene matrix, with or without mineral fillers, commonly found in MCM / ACP. The insulation is typically continuous, with the potential for rapid vertical fire spread in the absence of effective fire barriers. Air gaps and chimney spaces The combustibility of some of the facade materials can be compounded by the presence of air gaps behind or between the layers of the system. These air gaps can facilitate the spread of fire across the face of combustible materials, at the same time restricting access to the fire by fire fighters or automatic sprinklers. Chimney effects can occur when the facade systems are used on internal returns such as balconies or vertical intrusions that create opposing faces that reflect heat from burning materials onto adjacent surfaces. Figure 6 Evidence of air gap behind ACP panels and chimney effect in Lacrosse fire, Melbourne (Image Source: Peter Boyle, Zurich) Curtain wall systems Curtain walls are a continuous, non-structural, external covering spanning multiple floors and supported by mounts at the edge of each floor. This typically results in a gap between the edge of each floor and the curtain wall. This gap should be filled with firestopping during construction. However, natural expansion and contraction of the building over its lifespan (thermal movement) may allow firestopping to become loose or allow gaps to appear, creating a route for fire spread, which cannot be easily inspected or maintained. Generally, the taller the building, the greater the thermal movement is likely to be. This issue needs to be considered at the design stage. This presents a risk of fire spread from floor to floor that can be compounded by the use of combustible wall elements. Burning debris Experience with real fires has shown there is a threat from burning facade materials dislodged from heights falling and spreading fire to the lower levels of the building, or adjacent buildings, vehicles or other assets. 6

7 Guidance Full Scale Fire Tests & Listed Assemblies Recommended When systems with combustible components have been selected, consider replacing with a non-combustible alternative or a system considered to be a Zurich Recognized Solution. See Appendix A for more detail. Non-combustible components should be assessed using separate fire tests of each layer of the facade system (not testing of built up elements). Fire tests should be conducted using an accepted test method (e.g. ISO 1182) by a recognized testing authority. A variety of small-scale fire test have been used to evaluate combustible facades; however, as noted in the 2014 NFPA Research Foundation report tilted Fire Hazards of Exterior Wall Assemblies Containing Combustible Components (see References), it is not clear that small-scale fire tests have been validated using large-scale fire tests. Large-scale tests such as NFPA 285 provide an acceptable measure of the performance of potentially combustible facade systems. To qualify as a Zurich Recognized Solution, a system must include documented test results using an accepted test method by a recognized testing authority. Identification of Potential Issues on Site One of the key issues with the wide range of facade systems in use is the difficulty in identifying problematic installations once in service. EIFS systems can look like rendered concrete and aluminum combustible elements can look like solid metal sheeting, or they may be covering expanded polystyrene foam with an air gap. ACP can have a range of core materials which appear identical once installed. It may be possible to inspect the construction at service penetrations or other discontinuities, but this is unlikely to provide conclusive evidence as to the combustibility of the core. To help determine the exact make up of a facade system, refer to the as-built drawings and specifications, combined with a bill of materials as confirmation that no inappropriate substitutions have occurred during construction. In the absence of appropriate documentation it may be possible to remove part of the facade for inspection and testing by an appropriate testing authority. Solutions for Existing Installations Replacement Replacement of all combustible facade components with non-combustible or listed solutions is recommended to address the fire exposure. In the case of combustible MCM/ACP panels consider replacing the panels with fire rated, mineral filled alternatives. It should be noted that fire rated, mineral filled alternatives may be heavier than combustible panels and may provide a lower insulation rating. Fire breaks The use of fire breaks (such as bands of fire rated panels two stories tall) may be considered to reduce the likelihood of vertical fire spread; however, recent fires involving ACP have demonstrated the potential for fire spread down through the formation of burning droplets or brands. Considering this mechanism of fire spread, the use of fire breaks may not eliminate the risk of extensive fire spread. 7

8 There may be some potential for fire breaks to help limit the transverse spread of fire around the building. Vertical gaps of at least 5 meters (16 ft) made up of fire rated panels or non-combustible construction could help limit fire spread where combustible elements are limited to a few stories in height. However, the risk of burning droplets or brands from extensive vertical stretches of MCM/ACP of more than a few stories would likely negate the impact of these fire breaks. In EIFS systems, it may be possible to retrofit a thicker cementitious render coat where depth of cover is inadequate. Automatic fixed fire protection There may be some potential for automatic deluge water spray systems to control combustible facade fires by directing water onto the exterior facade wall surfaces. However, this is not likely to be a viable solution in many cases. The concern is with practical constraints encountered in providing adequate coverage, timely actuation, and sufficient water supplies in an existing high rise building which may render the approach an impractical solution. The presence of concealed voids in a facade system would also likely defeat any sprinkler or deluge solution. Fixed fire protection systems such as sprinklers do have a place in controlling ignition sources that expose a combustible facade. Fixed fire protection should be provided to all balconies and as exposure protection to hazards such as: Garden beds Rubbish skips and compactors Vehicle parking spaces Illuminated signs Balconies and terraces Control of Ignition Sources Risk Management Measures Good management of ignition sources can also help reduce the likelihood of fire. The following suggestions can help to reduce the probability of a loss involving combustible elements, but the potential for a large loss will remain unless the combustible insulation itself is also effectively addressed. A senior site manager should be appointed to take charge of the risk management program covering all aspects of risk control from fire training to planned maintenance. A documented site plan should be available to responding fire services that clearly shows the layout and type of panels used in the construction. To help protect combustible insulation from exposure to ignition sources, facings and joints need to be maintained and kept in good condition in order to retain the degree of fire resistance presented by the facings and to reduce the risk of fire spread to any void behind the panel. Regular inspections need to be 8

9 conducted to identify and rectify any exposed combustible insulation material and written records maintained. Repairs to combustible facades should never involve the use of welding or other obvious ignition sources. Hot Work should not be allowed in the vicinity of combustible materials, unless they are protected by noncombustible or purpose-made blankets, drapes or screens. A Hot Work Permit system must be in place and any work on panels should be subject to a risk assessment. Yard storage of combustible material, such as timber pallets or plastic crates must not expose walls containing combustible elements. Ensure a distance of at least 10 meters (33 ft) from buildings. Where these distances cannot be achieved then provide fire rated cut off walls to help reduce the risk presented by the storage of combustible materials. Outside electrical transformers with combustible dielectric fluids must not expose walls containing combustible elements. Ensure a distance of at least 15 meters (50 ft) from buildings. Where these distances cannot be achieved then provide fire rated cut off walls to help reduce the risk presented by the use of these combustible fluids. These types of transformers require increased distance from buildings due to the potential for a transformer to eject burning dielectric fluid under pressure when the transformer tank vents. Electrical inspection and testing should be carried out at least annually on electrical equipment and cabling in contact with combustible elements or more frequently as determined by risk assessment. Thermal inspection of the systems at regular intervals can be a cost effective and pro-active tool in helping to reduce the risk of electrically generated fires. Electrical services should not pass through insulated combustible elements. If this is unavoidable, the exposed core should be covered with metal flashing wherever possible. Enclose all electrical cables passing through insulated panels in conduits. Avoid attaching items to panels where possible. If this is unavoidable, then take steps to prevent the exposure of the insulation, and where necessary, thermal barriers should be in place around the fixing to prevent ignition of the panel. Security provisions should be appropriate to the arson exposure at the site and should at a minimum provide for effective perimeter fencing, lighting, and control of waste bins and yard storage whenever combustible elements are used on external walls. If a heater flue or other potentially hot trunking passes through combustible panels, it must be installed in a non-combustible insulating sleeve not less than 50 mm (2 inch) thick. Ensure that heat is not conducted to the composite panel by any flashing or covers. Proprietary sleeve systems that can achieve 60 minutes fire resistance in terms of integrity and insulation should be considered. Fill gaps between the collar and panels with mineral fiber or other suitable non-combustible material. Ensure that workshops, utilities and machinery rooms are fire isolated by means of fire compartmentation that can achieve a minimum of 60 minutes fire resistance. 9

10 Conclusion Whenever possible, consider selecting a facade system formed from noncombustible components. Where combustible components are selected, consider a system that is a Zurich Recognized Solution. A facade system that is considered a Zurich Recognized Solution, would need to be: Installed in accordance with their approval, certification, or listing Installed in accordance with manufacturer s guidance Maintained in good condition (no exposed core material) In cases where combustible components are in use, consider applying the guidance contained in this document. References External References Post Incident Analysis for Lacrosse Docklands FINAL. Richmond, Victoria, AU: The Metropolitan Fire and Emergency Services Board, 2014, Web, Web site accessed Nathan, White, Michael Delichatsios. Fire Hazards of Exterior Wall Assemblies Containing Combustible Components. Quincy, MA, USA: NFPA Research Foundation, Web. Web site accessed Zurich Risk Topics Construction Composite panels. Zurich, Switzerland. Zurich, Management Practices: Hot work Property and Business Interruption. Zurich, Switzerland: Zurich Zurich Recognized Solutions. Zurich, Switzerland: Zurich

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12 Appendix A Zurich Recognized Solutions Combustible elements which are considered to be a Zurich Recognized Solution are approved, certified, or listed by a Zurich Recognized Testing Laboratory based upon testing to an acceptable laboratory test protocol. In addition, these panels must be installed and maintained in accordance with their approval, certification or listing as well as manufacturer s guidelines. Zurich Recognized Testing Laboratory Acceptable laboratory test protocol Zurich Recognized Solution Zurich recognized property protection principles Manufacturer's guidelines Acceptable laboratory test protocols There is no single globally-acknowledged acceptable laboratory test protocol for evaluating combustible elements. A range of regional or national test protocols are available for composite panel evaluation. Avoid selecting combustible elements based upon intermediate-scale fire test protocols. Consider selecting combustible elements based upon a full-scale test protocol. Select a test presenting a rigorous fire exposure to the facade system under test. Full-scale fire tests may include both facade tests and room corner tests such as the most recent edition of the test protocols outlined below. Full-scale facade fire tests ANSI FM 4880 American National Standard for Evaluating: A) Insulated wall or wall & roof/ceiling assemblies; B) Plastic interior finish materials; C) Plastic exterior building panels; D) Wall/Ceiling coating systems; and E) Interior or Exterior Finish Systems BS Fire performance of external cladding systems - Part 1: Test method for non-loadbearing external cladding systems applied to the masonry face of the building BS Fire performance of external cladding systems - Part 2: Test method for non-loadbearing external cladding systems fixed to and supported by a structural steel frame CAN/ULC S134 Standard Method of Fire Test of Exterior Wall Assemblies DIN Brandverhalten von Baustoffen und Bauteilen - Besonderer Nachweis für das Brandverhalten von Außenwandbekleidungen, als Bestandteil der Zulassungsgrundsätze des Deutschen Instituts für Bautechnik (translation... Fire behavior of building materials and components - Specific Proof of the fire behavior of exterior wall claddings, as part of the approval principles of the German Institute for Building Technology) 12

13 ISO Reaction to fire tests on facades Part 2: Large scale test NFPA 285 Standard Fire Test Method for Evaluation of Fire Propagation Characteristics of Exterior Non-Load- Bearing Wall Assemblies Containing Combustible Components UBC 26-9 Method of Test for the Evaluation of Flammability Characteristics of Exterior, Nonload-bearing Wall Assemblies Containing Combustible Components Using the Intermediate-scale, Multistory Test Apparatus Note: UBC 26-9 uses the words intermediate-scale in its name as it was a reduced version of a larger-scale test, UBC 26-4 Method of Test for the Evaluation of Flammability Characteristics of Exterior, Nonload-bearing Wall Panel Assemblies Using Foam Plastic Insulation. SP FIRE 105 External Wall Assemblies and Facade Claddings Reaction to Fire Full-scale room corner fire tests EN Fire test. Large-scale room reference test for surface products ISO 9705 Reaction to fire tests. Full scale room tests for surface products. ISO Reaction to fire test for sandwich panel building systems -- Part 1: Small room test ISO Reaction-to-fire tests for sandwich panel building systems -- Part 2: Test method for large rooms NFPA 286 Standard Methods of Fire Tests for Evaluating Contribution of Wall and Ceiling Interior Finish to Room Fire Growth LPS 1181 Part 1 Series of Fire Growth Tests for LPCB Approval and Listing of Construction Product Systems Part One: Requirements and Tests for Built-up Cladding and Sandwich Panel Systems for Use as the External Envelope of Buildings LPS 1181 Part 2 Series of Fire Growth Tests for LPCB Approval and Listing of Construction Product Systems Part Two: Requirements and tests for sandwich panels and built-up systems for use as internal constructions in buildings UL 1040 Fire Test of Insulated Wall Construction UL 1715 Fire Test of Interior Finish Material Zurich Recognized Testing Laboratories A Zurich Recognized Testing Laboratory is a product certification body. They are evaluated by a third-party accreditation body for their ability to perform self-accreditation of their product testing. Qualified third-party accreditation bodies that accredit product certification bodies include members of the International Accreditation Forum, Inc. See See the RiskTopic Zurich Recognized Solutions for Property Risks for further discussion of Zurich Recognized Testing Laboratories. 13

14 Zurich Insurance Group Ltd. Mythenquai 2 CH-8022 Zurich Switzerland rt_combustiblefacades.docx The information contained in this document has been compiled and obtained from sources believed to be reliable and credible but no representation or warranty, express or implied, is made by Zurich Insurance Group Ltd. or any of its subsidiaries (hereinafter Zurich ) as to their accuracy or completeness. Some of the information contained herein may be time sensitive. Thus, you should consult the most recent referenced material. Information in this document relates to risk engineering / risk services and is intended as a general description of certain types of services available to qualified customers. It is not intended as, and does not give, an overview of insurance coverages, services or programs and it does not revise or amend any existing insurance contract, offer, quote or other documentation. Zurich and its employees do not assume any liability of any kind whatsoever, resulting from the use, or reliance upon any information, material or procedure contained herein. Zurich and its employees do not guarantee particular outcomes and there may be conditions on your premises or within your organization which may not be apparent to us. You are in the best position to understand your business and your organization and to take steps to minimize risk, and we wish to assist you by providing the information and tools to assess your changing risk environment. In the United States of America, risk services are available to qualified customers through Zurich Services Corporation and in Canada through Zurich Risk Services as also in other countries worldwide, risk engineering services are provided by different legal entities affiliated with the Zurich Insurance Group as per the respective country authorization and licensing requirements Zurich Insurance Group Ltd.