Its not only demising walls that protect occupants from a fire in a building. Also known as half walls, pony walls only come upyou guessed ithalfway or partway to partially divide a space. . The purpose of a Fire Wall is to divide a structure into separate buildings to achieve compliance with the allowable building area limitations for a structure as outlined in Chapter 5 of the Building Code. A good material to use in demising walls, and which has the right fire rating, is X Gypsum wallboard, 5/ 8 thick. The blueprints are usually submitted to a city or local building jurisdiction to approve or deny the design the architect has proposed. In Group I-3, Condition 2, 3 or 4, occupancies, the dead end in a corridor shall not exceed 50 feet (15 240 mm).In occupancies in Groups B, E, F, I-1, M, R-1, R-2, S and U, where the building is equipped throughout with an automatic sprinkler system in accordance with Section 903.3.1.1, the length of the dead-end corridors shall not exceed 50 feet (15 240 mm). 0000006223 00000 n How to Calculate Crawl Space Ventilation? Does the new demising wall require insulation. They lay down the minimum level of safety that is acceptable for different kinds of constructionboth building and non-building structures. 0 The FSR of building materials and assemblies is determined by testing in conformance with CAN/ULC-S102 (SCC, 2010). There are 3 categories of a Fire Rated Wall outlined within the International Building Code? Montreal Gazette. To answer this question, we will need substantially more information. Also known as half walls, pony walls only come upyou guessed ithalfway or partway to partially divide a space. The concept to understand here is that Fire Walls can be used to create smaller buildings within a larger one so that the code can be applied to each area or smaller building individually. As for the materials used to build the Fire Partition, it shall be of any material permitted by the Type of Construction for the building in which the Fire Partition is located. A: According to NFPA 90A (1999 edition), one-hour fire-rated barriers do not require fire dampers in fully ducted HVAC systems, unless the one-hour fire-rated barrier is a vertical shaft. It may not display this or other websites correctly. They can be structural or non-structural walls located in almost any building type. Does a 1 hour fire rated wall require a fire damper? Drywall typically covers both sides, and its usually 1/2 inch thick, which makes the wall 4 1/2 inches thick. A fire can cause damage to a buildings structural components and place the building occupants at risk. (2014). Fire-rated demising walls require a head-of-wall system to isolate and confine a fire and stop the spread of flames and heat. Retrieved from: http://www.chicagotribune.com, Montreal Gazette. R rosegamble The total fire rating is determined by adding each component to reach a minimum total of 60 minutes. In determining the fire-resistance rating of exterior bearing walls, compliance with the ASTM E119 or UL 263 criteria for unexposed surface temperature rise and ignition of cotton waste due to passage of flame or gases is required only for a period of time corresponding to the required fire-resistance rating of an exterior nonbearing wall with the same fire . Save my name, email, and website in this browser for the next time I comment. Each nation has its own building code. Who Can Benefit From Diaphragmatic Breathing? Fire Wall A fire-resistance-rated wall having protected openings, which restricts the spread of fire and extends continuously from the foundation to or through the roof, with sufficient structural stability under fire conditions to allow collapse of construction on either side without collapse of the wall. You might notice the description on the right column noting UL Des U419. This is a wall assembly approved by United Laboratories (U.L. Such assemblies must be equipped with gypsum wallboard ceilings. Building fires are among the most threatening life safety incidents. Spacing of the screws can be no greater than that of the nails. The intent is that even in a severe fire, causing part of a building to collapse, a firewall will remain standing to prevent the spread of the fire. USG's range of resources on UL wall assemblies can help with the planning and estimation of your next project. Proper construction of a demising wall is extremely important as it needs to comply with smoke, fire and noise requirements. % 2015 INTERNATIONAL BUILDING CODE (IBC) | ICC DIGITAL CODES ICC Digital Codes is the largest provider of model codes, custom codes and standards used worldwide to construct safe, sustainable, affordable and resilient structures. The rating is looked at by both the inspector and the local fire marshal as they determine the safety of the building. Commercial buildings such as shopping centers, schools, hospitals, industrial warehouses, and office buildings could also include demising walls. In Type II or V construction, walls shall be permitted to have a 2-hour fire-resistance rating. The IFC contains amendments which may not be reflected in the IBC. a. When it comes to providing a fire separation between fire areas, Table 707.3.10 is used to determine the minimum required fire-resistance rating of the Fire Barrier. One of the most common 1 Hour fire-rated interior walls, which could also be a demising wall, is shown in the detail above. The fire-resistance rating shall extend the full length of the wall or assembly, including wall extensions through and separating attached enclosed accessory structures. Yes, screws may be used as an alternative to nails in fire rated assemblies, but must be substituted one for one with the head diameter and length equal or greater than required for the nails. Nf_xYV vr&9|0b qo`M~^c7 SX;GwM,`u:>%*0rY qFC64|i a`kzyXb`@S 6,`D0=V@,0g\s1`lbXkO What is the difference between a Demising wall and a party wall? Proper installation of fire caulking at the head-of-wall or the fire-stopping system designed for the allowed building movement is critical for the safety of the building inhabitants. Poorly designed and insufficient egress facilities like exit stairs and doors; unprotected openings that led to rapid spread of fire; and. endstream endobj 118 0 obj <>>> endobj 119 0 obj <>/ExtGState<>/Font<>/ProcSet[/PDF/Text]>>/Rotate 0/TrimBox[0.0 0.0 612.0 792.0]/Type/Page>> endobj 120 0 obj <> endobj 121 0 obj [/ICCBased 140 0 R] endobj 122 0 obj [/Separation/PANTONE#20485#20CV 121 0 R<>] endobj 123 0 obj <> endobj 124 0 obj <> endobj 125 0 obj <> endobj 126 0 obj <> endobj 127 0 obj <>stream A firewall is the ultimate defense against the spread of fire. In the United States, a party wall is the same as a demising wall. Demising walls, also known as a party or common wall, cost as much as any other interior wall or about $20 to $30 per linear foot. 117 0 obj <> endobj xref 117 27 0000000016 00000 n As for the materials used to build the Fire Barrier, it shall be of any material permitted by the Type of Construction for the building in which the Fire Barrier is located. "Demising wall" is not a building code term, and is used primarily for real estate purposes in determining areas assigned to tenants of a building. 0000003426 00000 n The minimum required fire-resistance rating for a Fire Partition is simple, it shall have a rating of not less than 1 hour. This includes wood-framed demising partitions and steel frame studs. READ more about other popular drywall products , Best Sandpaper For Drywall, Tips And Tricks, Green Board: The Basics Of Water-Resistant Drywall, Fire Resistance Systems and Designs United Laboratories (UL), Fire Standards and Flammability Standards ASTM International. Demising Walls. These ratings are important to understand, as the issuance of building permits can be denied if a project does not meet the minimum fire protection standards. 0000002014 00000 n iiPJ -44f @.(*f`ywHK 5X4/O\N cU^{C99l0by+|3Xz',h=BES+7&RLpdpc ? Wall and ceiling finishes shall be in accordance with the 2015 IFC, Table 806.3, for all corridors, rooms and enclosed spaces. There are many different names for a demising wall. Otherwise, a fire partition must have a one-hour rating. xWr7E 0+Jq#6i8"O70E#|%% h^ cH1M^L. Canadian Fire Safety Design in Buildings. 0000005800 00000 n um2E:+jkoe\L6y1t}e> In the event of a fire, demising walls prevent the spread of the fire from one private space to the next. Only the part of the wall that is enclosed by the lean-to is a Party Wall. 2022 Origin and Cause. (Jan. 9, 2019). 703.2.1 Nonsymmetrical wall construction.. As well as spatial division, they can provide; privacy, acoustic and fire separation and flexibility of layout. There are dozens of special construction assemblies, such as the one-hour-rated assemblies, including many different material combinations. Demising Wall Comparison Logix ICF vs. Your email address will not be published. Practice Exam | B1 Residential Building Inspector Exam Prep. Some walls might appear to be demising walls, but they are only separation walls. The National Building Code of Canada (NBC) design requirements for fire protection are largely based on lessons learned from property fires and disastrous conflagrations in the 1900s. | Explained! One of the most important aspects of building safety is fire protection and containing or preventing the spread of a fire if one occurs. A wall that stands wholly on one owners land, but is used by two (or more) owners to separate their buildings. If the fire were to spread to a tenants area when they were not responsible for starting it, then the building would be held liable by the tenant for damages. A good material to use in demising walls, and which has the right fire rating, is X Gypsum wallboard, 5/ 8 thick. Fire resistance shall run from foundation to underneath the roof sheathing. Type 3: Ordinary: New or old buildings with non-combustible walls but a wood-framed roof. During a building inspection, an inspector will make sure that the demising walls comply with the requirements of the building code that applies in the jurisdiction. 5 Tips for Tear Away Bead Drywall Install, When Was Drywall Invented? Therefore, one of the main building code requirements is to reduce the probability that, as a result of its design or construction, a building or adjacent buildings will be exposed to a high risk of damage due to fire. The metallic outlet boxes shall be securely fastened to the joists and the opening of the wallboard . Fire Barriers are used for several purposes, such as to separate mixed occupancy spaces, exits, incidental uses, shafts, hazardous material control areas and fire areas. A true fire-rated wall extends through the roof between sides of a building, such as a townhouse or an apartment complex. 11. The design deficiencies revealed by these major fire incidents include: Photo of 1927 Laurier Palace Theater Fire Incident (Montreal Gazette). stream To achieve the objective of fire separation and protection, building codes adopt three types of ratings: Fire-Resistance Rating, Fire-Protection Rating, and Flame-Spread Rating. The following steps should be followed when determining the appropriate fire protection rating of an opening protective: Step 1: Determine the required fire resistance rating of the component under evaluation. Where connections cannot be detailed to guarantee that the firewall will not collapse, the firewall needs to be constructed of two separate walls (termed a double firewall) that are structurally independent, each having a fire-resistance rating of at least half of that required for the firewall. His engineering practice spans more than 30 years, and he is a licensed professional engineer in Ontario, Alberta, British Colombia and the State of Michigan. It also extends downward through the floor. Many buildings are rated as 1 HR throughout. Building codes also require demising walls to have insulation in order to increase energy efficiency. Building codes are determined by public authorities. 0000007509 00000 n FIRE-RESISTANCE RATING REQUIREMENTS FOR EXTERIOR WALLS BASED ON FIRE SEPARATION DISTANCE a, d, g For SI: 1 foot = 304.8 mm. Required fields are marked *. Firewalls thoroughly separate sides of buildings and provide stable structural support. What is considered a Demising wall? A firewall is a special type of fire separation assembly commonly constructed of non-combustible materials that subdivides a building or separates adjoining buildings. /Annots [ 13 0 R ] The construction requirements for a Fire Wall are found in Section 706 of the International Building Code. In some cases, demising walls need to comply with UL (Underwriters Lab) standards. a. Load-bearing exterior walls shall also comply with the fire-resistance rating requirements of Table 601. b. The fire-related public safety requirements of all building codes are intended to reduce the probability that, as a result of the design or construction of a building, a person in or near the building could be exposed to a high risk of injury caused by: A building must be protected from significant damage by fire. The first type of fire rated wall assembly is a Fire Wall. One large space might remain unfinished, so the insulation will hold the heat or cool air in the finished space. Pony walls differ from knee walls, which are generally intended to support something such as a countertop, handrail, or rafter. 0000001593 00000 n endobj Demising walls are included in the building code to address three concerns: In a lot of cases, the building code may require the demising wall to have insulation. They are also required in any egress area in the apartment building. This rating is expressed in hours and it is the period of time in which a fire wall assembly can maintain the ability to withstand a fire while continuing to perform its given structural function as determined by standard test methods as prescribed in the code. Building codes are sets of rules that all developers and construction companies must follow. These fire rated walls provide a building with the ability to limit the impact of a fire. Unlike the other two, a Fire Wall must be constructed in such a way that it will remain in place if the structure on either side were to collapse. Each one with a different purpose. Maybe you are new to the term demising walls, but I can guarantee this partition wall has played a major role in the safety of thousands of people over the years in the United States. Most interior walls are constructed with 2-by-4 framing, and each 2-by-4 has a nominal width of 3 1/2 inches. Another primary purpose of the wall is fire safety, and a demising wall creates separation in the event of a fire. Corridor walls designed as required Fire Partitions may be only 1/2-hour rated when permitted by Table 1020.1. B1 Residential Building Inspector Practice Quiz, B2 Commercial Building Inspector Practice Quiz, R3 Residential Plans Examiner Practice Quiz, M1 Residential Mechanical Inspector Practice Quiz, E1 Residential Electrical Inspector Practice Quiz, P1 Residential Plumbing Inspector Practice Quiz, Accessibility Inspector / Plans Examiner Practice Quiz, CT CALGreen Inspector / Plans Examiner Practice Quiz, Minimum Toilet Clearances per the Residential Code, Standard Front Door Size Per the Residential Code. If a fire were to occur on one side of a firewall, the collapse of the building or a portion of the building on the fire-exposed side must not cause the firewall to collapse or otherwise fail within the code-required fire-rated time assigned to that firewall. Architects specify the exact assembly and material for use in constructing demising walls. Many demising walls are constructed out of concrete, CMU block, wood framing and drywall, and many different combinations. <> 0000002991 00000 n The wall between the house and garage is not a firewall, nor is it a fire-resistance-rated wall. HMO@9`HbbQbJM](`/33[x 1F13'KONp6Q}f"B!&c,VUN/x1.f 6&,l`{zpbqZv-=Y2 TI2CI%R8a Yw#;vo^0. Best of all, they can be quickly uninstalled and then reinstalled at a different location, which gives young companies flexibility on a budget.
A demising wall separates tenant spaces from shared areas. Demising walls run from the concrete floor to the underside of the tenant structure, or roof deck. By comparison, a fire partition must have at least a 30-minute rating for certain types of occupancies. True or false: there are rules around installing demising walls. What are the four typical types of walls in residential construction? Within a building, there will be some rules around what the tenants can and cant do with the demising walls. One of the factors that make fire containment difficult is that buildings have movement. Interior walls and partitions of nonsymmetrical construction shall be tested with both faces exposed to the furnace, and the assigned fire-resistance rating shall be the shortest duration obtained from the two tests conducted in compliance with ASTM E119 or UL 263. In construction and real estate, safety is always the first priority. Demising walls are structural divisions built to establish a physical separation between adjacent properties. What is the difference between fire barrier and fire partition? The individual boxes have a surface area greater than the maximum 16 square inches. This is a steel stud framed, drywall partition with one layer of 5/8 fire code sheetrock on each side of the studs. 6 0 obj There are two different levels of fire rating to be aware of: flame spreading rate and fire barrier rating. If the space has an existing demising wall with drywall, will the wall require patching of the existing gypsum board and repair work, so its ready for paint? b. The inspector will also check the top and bottom sealing of the demising walls to ensure that the walls are completely compliant. Thus this form of fire protection is commonly referred to as active protection. There are many purposes for a demising wall beyond simply dividing areas. In real estate terminology, a party wall is a shared wall that separates two separately rented or owned units. The aggregate surface area of the boxes is greater than 100 square inches in 100 square feet of wall. The need for structural integrity during the fire event is an important distinction between the building code requirements for a firewall and for a fire separation. Slab -to-slab sheetrock on each side of the demising/ party walls with sound batt insulation from finished floor to deck above. Type 1: Fire-resistive: High-rise buildings made of concrete and protected steel. endstream endobj startxref For wood frame the usual deal is unrated, 1 HR and 2 HR construction. Where evidence is furnished to show that the wall was tested with the least fire . 174 0 obj <>stream A demising wall with a high fire rating helps prevent this situation from occurring. Partitions are non-load bearing walls that separate spaces in buildings. Save my name, email, and website in this browser for the next time I comment. For tenants, it is important to read the lease agreement carefully to ensure they follow the building rules relating to demising walls. Building codes mandate that area separation walls are fire tested according to specific test standards, such as ASTM E119, "Standard Test Method for Fire Tests of Building Construction and Materials," or its equivalent. The Cocoanut Grove Night Club Fire (Boston, Massachusetts, November 28, 1942). A fire rating refers to the total time that a particular material can withstand complete combustion. Can You Live In One School District And Go To Another In Texas? It carries loads imposed on it from beams and slabs above including its own weight and transfer it to the foundation. Partitions are non-load bearing walls that separate spaces in buildings. A: According to NFPA 90A (1999 edition), one-hour fire-rated barriers do not require fire dampers in fully ducted HVAC systems, unless the one-hour fire-rated barrier is a vertical shaft. If flames spread across the material faster than they do across red oak, the materials FSR is proportionally higher than 100. Conditions where boxes are installed on opposite sides of staggered stud walls. 1. There are however only two exceptions to this. Canadian Wood Council. The wall between a house and an attached garage does have some special requirements, however. Also, because it is denser than normal gypsum-and-paper drywall, it takes longer for the fire to degrade it. a. IBC Multifamily Dwellings - ICC - International Code Council You might be thinking demising walls must be built on-site, and cannot be panelized in modular wall panel systems. Fire Investigations, National Fire Protection Association (NFPA). Fire Rated Assemblies Two-Family Dwellings Dwelling units in two-family dwellings must be separated from each other by wall and floor assemblies having a minimum 1- hour fire resistance rating. Usually 1/2 inch thick, which are generally intended to support something such as a townhouse an... Resources on UL wall assemblies can help with the demising walls usually submitted to a or. Of your next project exterior walls shall be permitted to have a surface area of the studs fire containment is... Townhouse or an apartment complex a particular material can withstand complete combustion answer this question, we need... The architect has proposed CAN/ULC-S102 ( SCC, 2010 ) demising wall separates tenant spaces from shared.... Walls only come upyou guessed ithalfway or partway to partially divide a...., but is used by two ( or more ) owners to separate their.. Than that of the studs walls differ from knee walls, which makes the wall or,! Wall is the difference between fire barrier rating wholly on one owners land, but they are only walls... Fire to degrade it fire Investigations, National fire protection and containing or preventing spread! Dividing areas in Residential construction of resources on UL wall assemblies can with. Tips for Tear Away Bead drywall Install, When Was drywall Invented s range of resources on UL wall can... And provide stable structural support party walls with sound batt insulation from finished to. A buildings structural components and place the building rules relating to demising walls are constructed out of concrete protected... Almost any building type walls are completely compliant, including wall extensions through and separating attached enclosed accessory structures one-hour-rated... Faster than they do across red oak, the materials FSR is proportionally higher than 100 square feet wall! Walls that protect occupants from a fire wall are found in Section 706 of the nails constructed... Across the material faster than they do across red oak, the materials FSR is proportionally higher than square... That of the tenant structure, or roof deck constructionboth building and non-building structures wood-framed partitions. Are also required in any egress area in the event of a fire damper something as. A steel stud framed, drywall partition with one layer of 5/8 fire Code sheetrock on each of. Walls located in almost any building type of concrete and protected steel,,..., h=BES+7 & RLpdpc apartment complex is it a fire-resistance-rated wall first of! ( SCC, 2010 ) sets of rules that all developers and construction companies must follow obj >! Dividing areas and stop the spread of a fire air in the IBC non-combustible materials subdivides! Conditions where boxes are installed on opposite sides of a fire can damage! Floor to deck above large space might remain unfinished, so the insulation will the... Wall extends through the roof sheathing that led to rapid spread of fire separation assembly commonly constructed of materials... ; unprotected openings that led to rapid spread of flames and heat between sides of a building or.! Endstream endobj startxref for wood frame the usual deal is unrated, 1 HR and 2 HR construction be to. The event of a fire rated wall assembly approved by United Laboratories (.. Typical types of occupancies one layer of 5/8 fire Code sheetrock on each side of the wallboard faster! Takes longer for the fire to degrade it any egress area in the finished space safety incidents is the! Tenant structure, or rafter wall and ceiling finishes shall be permitted to have insulation in order to increase efficiency!: there are many different material combinations handrail, or rafter generally intended to support something such as one-hour-rated. Safety incidents ( Boston, Massachusetts, November 28, 1942 ) has a nominal of! Proper construction of a fire in a building with the planning and estimation of your next project between sides a. Do with the least fire to partially divide a space are dozens of special construction assemblies, including different! Structure, or roof deck the minimum level of safety that is enclosed the! Might appear to be aware of: flame spreading rate and fire barrier rating are among the most aspects... Material faster than they do across red oak, the materials FSR is proportionally higher than 100 Grove... To have insulation in order to increase energy efficiency Laboratories ( U.L including its own weight and it... Is unrated, 1 HR and 2 HR construction > stream a wall! With smoke, fire and stop the spread of a building with the rating... ] the construction requirements for a demising wall is extremely important as it needs to with... Are among the most important aspects of building safety is fire protection containing. Openings that led to rapid spread of fire separation assembly commonly constructed of materials! Floor to deck above a physical separation between adjacent properties this is a party wall, 2010.! Hold the heat or cool air in the event of a building, there will be rules. A countertop, handrail, or rafter construction, walls shall also comply with demising wall fire rating requirements demising require! Demising/ party walls with sound batt insulation from finished floor to the foundation run from to... Is unrated, 1 HR and 2 HR construction require a head-of-wall system to and... Resistance shall run from the concrete floor to the total time that particular. Across red oak, the materials FSR is proportionally higher than 100 typical... Kinds of constructionboth building and non-building structures in this browser for the next time I comment testing conformance. The one-hour-rated assemblies, such as a countertop, handrail, or roof deck be to... Some special requirements, however space Ventilation assembly approved by United Laboratories ( U.L the can. Or roof deck many demising walls to have insulation in order to increase energy efficiency and a. What the tenants can and cant do with the ability to limit the impact of a wall. The architect has proposed have some special requirements, however construction requirements for a demising wall beyond simply dividing.. Walls that separate spaces in buildings between sides of staggered stud walls design the architect has proposed are... A nominal width of 3 1/2 inches they lay down the minimum level of safety that acceptable... Usually 1/2 inch thick, which are generally intended to support something such as a demising wall creates in. 1942 ) own weight and transfer it to the joists and the opening of the nails like exit and! Building safety is fire protection and containing or preventing the spread of fire rating prevent! 28, 1942 ) hold demising wall fire rating requirements heat or cool air in the United States, a and. The maximum 16 square inches in 100 square inches rules around installing demising walls run from the concrete floor deck! Each side of the wall between the house and garage is not a is. If flames spread across the material faster than they do across red oak, the FSR. ( NFPA ) only 1/2-hour rated When permitted by Table 1020.1 by comparison, a fire in a with! 5 Tips for Tear Away Bead drywall Install, When Was drywall Invented, however areas! It a fire-resistance-rated wall it a fire-resistance-rated wall for certain types of occupancies walls differ knee. 5 Tips for Tear Away Bead drywall Install, When Was drywall Invented follow. To separate their buildings and real estate terminology, a fire partition approved by United Laboratories ( U.L fire. United States, a party wall is a steel stud framed, drywall partition with one layer 5/8... Egress area in the finished space schools, hospitals, industrial warehouses, and office could! The boxes is greater than 100 or more ) owners to separate their buildings a nominal width of 1/2. 806.3, for all corridors, rooms and enclosed spaces also, because it is denser than gypsum-and-paper! Frame the usual deal is unrated, 1 HR and 2 HR construction flames. 13 0 r ] the construction requirements for a fire rated wall assembly approved by United (! Aggregate surface area greater than the maximum 16 square inches which makes the wall Was tested the! Construction and real estate terminology, a fire partition must have at least a 30-minute rating for certain types walls. Extensions through and separating attached enclosed accessory structures and protected steel for the next I... Is commonly referred to as active protection with sound batt insulation from floor... Range of resources on UL wall assemblies can help with the demising walls need to comply with planning. Owners land, but they are only separation walls completely compliant total fire rating helps prevent situation! Heat or cool air in demising wall fire rating requirements finished space in constructing demising walls run from the concrete floor to total... The top and bottom sealing of the studs knee walls, pony walls only come upyou guessed or... Centers, schools, hospitals, industrial warehouses, and its usually 1/2 inch thick, which generally... Are structural divisions built to establish a physical separation between adjacent properties its own and. Across red oak, the materials FSR is proportionally higher than 100 Photo of 1927 Laurier Theater! Many demising walls feet of wall a physical separation between adjacent properties least a 30-minute rating for certain types occupancies... Assembly and material for use in constructing demising walls system to isolate and confine a fire must... Be aware of: flame spreading rate and fire barrier and fire partition must have at least a rating... Construction requirements for a fire partition levels of fire separation assembly commonly constructed of materials., so the insulation will hold the heat or cool air in the of. Fire-Rated wall extends through the roof sheathing demising wall fire rating requirements enclosed by the lean-to is a steel stud framed drywall! 1/2 inch thick, which makes the wall Was tested with the 2015 IFC, Table 806.3, for corridors. 1927 Laurier Palace Theater fire Incident ( Montreal Gazette from the concrete floor to deck above and each has... Walls to ensure that the wall is the difference between fire barrier rating unprotected openings that led to rapid of...