Exterior insulation fire first
Building's exterior wall is an important part of building energy efficiency, the core insulation material. Thermal conductivity of different types of materials are quite different, the smaller the thermal conductivity, its thermal insulation performance is better, in general, organic insulation material thermal performance is superior to the general inorganic insulation material.

Countries in the world, is currently our insulation materials are mostly organic polymer foam insulation materials, such as molded polystyrene board (EPS), extruded polystyrene board (XPS), polyurethane rigid foam, etc., although the corresponding product standards We have raised the requirements for flame retardance, but limited to the technical level and technical conditions of the current application, which essentially still combustible materials, fire-retardant material itself can not meet the performance indicators building fire safety requirements.

"Exterior insulation system" refers to the attached building facades, located outside the main building structure exterior wall systems, building from the insulation. EIFS and paste can be used, a variety of construction methods spraying, pouring and mechanical anchoring, etc., but the insulation material is attached directly to the primary wall, external decorative coating material may be, brick, stone, metal plates, etc. It can also be made wall insulation system with keel. There are primary wall system as a support, there is no primary wall full curtain wall system Write content included in the study. According to the advanced experience of foreign countries, to take a scientific moderate fire resistant construction measures for different types of exterior insulation and finish systems (such as setting fire buffer zone, thick fire protection layer) to meet the overall structure of the finished building fire safety requirements, ensure that buildings the fire will not spread when the fire broke out.

Therefore, to improve the overall thermal insulation system shall be constructed as an important way to improve the thermal insulation system fire safety performance of the building's exterior.

Fire first evaluation test
External insulation system fire safety performance evaluation on a pilot basis, using the test model should be able to characterize the state of the system in actual fire, the test results should objectively reflect the performance of external thermal insulation fire safety system. Only select the correct test method to objectively and scientifically evaluate the thermal insulation system fire safety performance.

Category scale division sample from test methods, including small size test specimens, the test specimen size and large-size model fire tests. Mainly small-scale tests on the combustion performance of insulation materials tested; the dimensions of the combustion test can be tested performance of insulation materials, can also be tested for insulation systems have some structure, but the system configuration covered is often limited ; large-scale tests can all construct the entire external thermal insulation system for inspection.

For fire safety performance or flame propagation whole insulation system configuration, mainly large-size model of the tests of fire. There are currently two experimental basis in China has a large-scale test method: First, the United States UL1040: 2000 standard, currently known as the "corner fire test"; the second is the British BS8414-1: 2002 standard, currently known as " window fire test "is also fire test methods for external thermal insulation system used internationally.

Corner fire test in the United States UL1040 represented. When the test fire source is located in the corner test model, test model and test results more applicable in the insulation. Window to the British BS8414 fire test is representative of the test fire source located at the bottom of the combustion chamber test model simulation window, the test model and test results are more suitable for outer insulation.

In order to BS8414-1: 2002 standards into test and evaluation methods for me abroad wall insulation system applications in 2008, the Chinese Academy of Sciences Institute of Architecture fireproof construction applied for the Ministry of Housing and Urban Construction industry standard "building exterior wall insulation system fire test method "of preparation tasks. After dozens of experimental research of a large proportion of window fire, is not equivalent to the establishment of the British BS8414-1: 2002 is prepared in principle, it has entered the approval stage. In the window fire test "Fire Test Method for building exterior insulation system" provisions, the test model to simulate the vertical plane of the building by the main wall and perpendicular to the sub-wall composition. The outer surface of the insulation system is installed in the building. Opening test model to simulate the actual construction of the combustion chamber at the bottom of a window or hole in the floor, lighted wood or gas flame overflow from the window, when the flame flashover after overflow from the window or hole in the external insulation system attacks occurred in the simulated room inspection extent of the damage external thermal insulation system, and their determination of flame propagation. Test fire source is about 400kg of wood, the total heat release of approximately 30 minutes 4500MJ, peak heat release rate of approximately (3 ± 0.5) MW, under normal conditions of use than the inner architecture of combustible material much larger amount, test conditions are very harsh.
The probability of actual fire attack from the building point of view, China Academy of Building Research Institute of Fire and Building Related research team together, choose a window fire test methods that have universal significance. From March 2006 until the beginning of November 2011, the research team for the different configurations of EIFS, has conducted 56 large-scale model test fire insulation system, wherein the corner fire test 10 times, window fire test 46.

Test results
1.EPS EIFS
(1) to take rock wool Fire Barrier Systems for EPS, determined after the test system is low flame propagation, rock wool Fire Barrier 20cm effectively prevent vertically upward flame spread role, especially trials EPS the thickness of the plate reaches 20cm, with sufficient combustible material. Thus obtained can be analyzed at the window fire test conditions, the system set 20cm rockwool firebreak enough to restrain the spread of flame effect.
(2) to take a block of rock wool fire beams for EPS system, after the test system determines a lower flame spread, visibility rockwool fire-Beam also has some prevent flame spread vertically upward effect.
(3) for the use of polyurethane composite structure as a firebreak of EPS thin plastering system after the test system determines a lower flame propagation, polyurethane composite structure firebreak 30cm effectively prevent vertically upward flame spread effect, the flame Reach is limited to the first fire Barrier less, more prominent role. But if the quality of the system itself there is a big problem, fire retardant Fire Barrier is limited. If the test showed 10 have flame propagation characteristics, causes and construction quality related. In the test 10 to 17 minutes after the start of the ignition for 20 seconds, wipe the surface of the mortar fiberglass mesh oblique fracture occurred. After ignition start 17 minutes and 55 seconds, dangling from the edge of the surface layer of the upper part began to be lit 11 seconds after the occurrence of flashover. It follows that the role of the fire Fire Barrier is relative, it effectively prevents the spread of flame premise should be the quality for EPS insulation system to meet the requirements of relevant standards.
(4) Phenolic insulation composite panels for fire buffer zone for EPS system, the system is determined after the test flame propagation low phenolic composite panels fireproof isolation belt 30cm effectively prevent vertically upward flame spread effect; foam cement for pick along EPS thin plastering system of composite rock wool fire Barrier, after the test system determines a lower flame spread, and further proof of the role of the fire rock wool fire buffer zone; for the powder particles of polystyrene board thin plaster Attaching to polystyrene gray exterior insulation system, determined after the test system is low flame propagation.
(5) For the protection of EPS using thick protective layer comprising powder particles of polystyrene insulation slurry, expanded glass beads of mortar fire insulation, steel mesh tile finishes, tile and fiberglass mesh finishes and other tests. The results showed that the test has been done in the thick protective layer system, at low flame propagation test status.

2. The polyurethane foam exterior insulation system
(1) did not take any structural measures for the polyurethane foam thin plaster system is determined after the test system is low flame propagation. It is believed that in the window fire test conditions, polyurethane foam and thin plastering system of fire risk is small, you can not set fire buffer zone.
(2) for the use of polyurethane foam systems thick protective layer, a total of five tests: including spray polyurethane foam exterior insulation system, fire-resistant high-strength composite plant fiber insulation boards scene pouring polyurethane foam exterior insulation system, spray polyurethane foam plus rockwool cavity wall insulation tape closure system, 8cm polyurethane foam sheet -2cm perlite mortar noodles.
In five trials, the system flame propagation were lower, showing a good reaction to fire performance. It is believed that when using thick protective layer of polyurethane foam with less risk of fire.

3.XPS EIFS
XPS EIFS total of three tests: including extruded polystyrene board thin plaster exterior insulation system - Fire Barrier wool board, adhesive polystyrene attach to XPS board puzzle plaster systems, extruded polystyrene thin plaster exterior insulation system (this test uses the B1 level extruded polystyrene board).

Among them, the use of rock wool Fire Barrier systems, low flame propagation properties; powder polystyrene particles using thick protective layer system, flame propagation low.

Analysts believe that the use of B1 level XPS board without setting fire buffer zone to ensure that the system has adequate fire safety performance has a certain degree of difficulty.

4. Phenolic - aluminum veneer curtain wall system
For Phenolic - aluminum veneer curtain wall system a total of 2 trials, 27 trials and 29 trials.

Test 27 phenolic composite aluminum thin plaster board wall systems, 7cm phenolic insulation board, adhesive bonding point box mode (bond area ≥40%), an internal system does not take other fire construction method, the test condition damage is more serious, with some flame propagation. 29 test method using paste bricklaying construction method phenolic insulation boards, fully adhered (bonded area 100%) in the interior insulation board is divided positions, wipe the surface 1cm powder particles of polystyrene and polyethylene powder used in curtain wall keel benzene particles plugging in test status showed good fire safety performance, lower flame propagation.
 
Test Conclusions and Recommendations
Comprehensive Test Results of the research group and the various types of insulation materials fire protection system performance analysis, preliminary draw the following conclusions:

1. external fire performance thermal insulation system
(1) B2 level of EPS boards - thin plastering system has a certain fire resistance. Setting fire buffer zone in the system (also set fire-beams), it can make the overall system performance to further improve fire safety, reduce the risk of spreading the flame.
(2) 20cm of rock wool fire buffer zone to meet the needs of isolated fire, flame arresters have sufficient capacity.
(3) B2 class polyurethane foam flame propagation system Plastered less, do not set fire buffer zone.
(4) The use of thick protective layer of exterior insulation system is low flame propagation, the system may not be provided within the fire buffer zone.
(5) external insulation systems, external insulation, such as the presence of cavities, the need for effective sealing to reduce the risk of fire spreading.

2. The impact of construction quality of external fire performance of the insulation system
Construction quality thermal insulation system for fire resistance of the protective layer system is essential.
Expanded polystyrene board thin plaster exterior insulation system October 21, 2008 conducted - Polyurethane foam insulation board fire buffer zone expanded polystyrene board test and March 18, 2009 conducted by thin plaster exterior insulation system - along pick test, the testing process have emerged a large area of the protective surface layer is instantly opened phenomenon, leading to internal system insulation material exposed in the air, and produce sharp combustion system increases the risk of flame propagation.

Therefore, the construction process must be strictly in accordance with the relevant standards for construction operations, to avoid reinforcing mesh dry lap. Construction is best to follow the order of top-down or bottom-up approach to ensure that the outer insulation joints within the system there is no big gap, thereby reducing the risk of damage in case of fire conditions.

3. Basic requirements for insulation materials
Combustion properties used in exterior insulation insulation materials should not be less than the B2 level, and in strict accordance with product standards-related material witness sampling and testing requirements. For polyurethane foam, the combustion performance requirements of class B2 plus oxygen index ≥26%; for EPS, the combustion performance requirements of class B2 plus oxygen index ≥30%; for XPS, combustion performance requirements for the B2 level.

Under the existing level of production technology to achieve the conditions recommended XPS increase the oxygen index of requirements to control the combustion properties of the material, which can be defined as the technical indicators: oxygen index ≥26%.

Take effective fire prevention measures in construction design and construction, the effectiveness of a large proportion of the window by the fire test test structural measures, combined with the combustion performance of insulation material grade not lower than B2 level and limit oxygen index of the material, to ensure that the building around fire safety protection structure is simple and easy new way, in our country has a broad application prospect research.

4. Fire Tests of Significance
Corner fire tests and fire tests the window exterior insulation system, particularly the fire test window can simulate the building interior and exterior of the building fire attack, model size to cover all systems, including the construction includes a fire cut off, can test status EIFS full response in the actual fire in the fire resistance, can be used to evaluate the overall exterior insulation system of ignition and propagation. The probability of actual fire attack from the building point of view, the window fire test more general sense, window fire test should be the focus of future research.

Industry standard "Fire Test Method for building exterior insulation system," the British Standard BS8414-1: 2002 converted to adapt to China's national conditions, more operational EIFS fire test methods, is China's first compiled large fire test method standard for exterior insulation system, will provide fire safety performance evaluation of my foreign wall insulation system science harmonized test methods, to improve the fire performance of my study abroad insulation systems, external insulation systems promote technological progress, and guide the healthy development of the outer insulation industry has a positive role.
 
Source: China Network mortar