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A ''' | A '''fire wall''' is a separating wall intended to restrict fire spread while maintaining the required resistance and structural stability. Its role combines the thermal and structural functions of building construction. In NUREG-1805's description of United States practice, a fire wall is distinguished from a barrier used alongside other protective measures.<ref name="KH_1-155">Kodur and Harmathy (2002), p. 1-155.</ref><ref name="N_17-7">Iqbal and Salley (2004), p. 17-7.</ref> | ||
The complete separation includes the wall's supports, ends, roof junction and protected openings. Fire can pass around an otherwise effective wall or through a damaged penetration. Some fire walls are designed to remain stable after construction collapses on either side, but that capability must be part of the stated design.<ref name="N_17-8">Iqbal and Salley (2004), p. 17-8.</ref><ref name="IFEG_1.6-6_1.6-8">Australian Building Codes Board et al. (2005), pp. 1.6-6–1.6-8.</ref> | |||
The | A fire-resistance duration alone does not describe all these conditions. The construction, exposure, support and required endpoints determine what the evidence demonstrates. Wall terminology and detailing provisions also differ between regulatory frameworks. Historical examples therefore need their document and jurisdictional context to remain explicit.<ref name="M_4-209_4-211">Milke (2002), pp. 4-209–4-211.</ref><ref name="N_17-7" /> | ||
== | == Fire wall and fire barrier terminology == | ||
NUREG-1805 distinguishes two related forms of separating construction in its discussion of United States practice. A fire wall separates buildings or subdivides a building while providing resistance and structural stability. A fire barrier restricts spread and extends to the floor or roof deck above. The distinction follows the report's description of NFPA 221.<ref name="N_17-7" /> | |||
The same account differentiates the assumed fire conditions. The fire wall is intended to remain stable during an uncontrolled fire without effective sprinkler protection. The barrier is considered alongside other protective measures, such as sprinklers. This identifies the performance basis within that framework rather than making the terminology universal across countries.<ref name="N_17-7" /> | |||
[[File:fse-fire-wall-v1.svg|thumb|upright=1.5|alt=Fire wall stable during uncontrolled fire and fire barrier working with sprinklers.|Fire wall and fire barrier have different design roles. Based on Iqbal and Salley (2004), p. 17-7.]] | |||
A | Both constructions can contribute to [[Fire compartmentation]], but their structural assumptions can differ. A wall's label does not independently explain whether surrounding construction may fail while the wall remains standing. That condition needs to be part of the design basis. Iqbal and Salley state that some fire walls are specifically designed to survive collapse on either side.<ref name="N_17-7_17-8">Iqbal and Salley (2004), pp. 17-7–17-8.</ref> | ||
== | A time rating is also a different description from structural independence. The rating concerns specified performance under a defined exposure. Independence concerns the relationship between the wall and the structures around it. A design needs evidence for whichever combination of those functions it claims.<ref name="KH_1-155" /><ref name="M_4-209_4-210">Milke (2002), pp. 4-209–4-210.</ref><ref name="N_17-8" /> | ||
== Heat transmission, openings and stability == | |||
[[Fire resistance criteria]] distinguish structural adequacy, integrity and insulation where those functions apply. Heat can pass through a wall even if the wall remains standing and has no opening. Cracks can permit gases or flames to pass before widespread collapse. These different mechanisms cannot be represented by observing only whether the wall is visibly upright.<ref name="KH_1-155" /><ref name="IFEG_1.6-7">Australian Building Codes Board et al. (2005), p. 1.6-7.</ref> | |||
The insulation function depends on heat transfer through the construction. A thick material can develop a hot exposed surface while its interior remains cooler. Conductivity, heat capacity and exposure duration affect this temperature distribution. A description of noncombustibility does not by itself establish how long the unexposed surface remains within a specified limit.<ref name="VR_5.2">Van Rossum (2027), §5.2.</ref><ref name="M_4-210_4-211">Milke (2002), pp. 4-210–4-211.</ref> | |||
Integrity concerns routes through the wall. Openings may be present initially or develop through damage, cracking or failed protection around services. The International Fire Engineering Guidelines consider these routes separately from conduction through intact material. The neighbouring fuel and its exposure determine whether passage through a route develops into another fire.<ref name="IFEG_1.6-6_1.6-7">Australian Building Codes Board et al. (2005), pp. 1.6-6–1.6-7.</ref> | |||
= | Stability includes the wall and any structural support it relies on. The guidelines note that a barrier may fail when its supporting member fails. They also require consideration of the effects on other barriers after structural failure. A separate wall rating cannot remove this dependency from the assembled building.<ref name="IFEG_1.6-8">Australian Building Codes Board et al. (2005), p. 1.6-8.</ref> | ||
== Continuity at roofs, ends and penetrations == | |||
A wall can be bypassed at its edges even if the main surface performs as intended. Iqbal and Salley describe exterior wing walls at the ends of fire walls to restrict spread around them. They also describe a parapet continuing through and above the roof. These are examples of completing the separation in their United States technical context.<ref name="N_17-8" /> | |||
[[File:fse-fire-wall-v2.svg|thumb|upright=1.5|alt=Wing walls close the ends and a parapet carries the fire wall through and above the roof.|Wing walls and parapets close fire-wall bypass routes. Based on Iqbal and Salley (2004), p. 17-8.]] | |||
The roof junction can otherwise connect the spaces on either side of the wall. The 2005 International Fire Engineering Guidelines identify concealed roof and ceiling spaces as possible routes between enclosures. A separating line in an occupied room does not automatically close those spaces. The boundary must be understood through its full extent and connections.<ref name="IFEG_1.6-6">Australian Building Codes Board et al. (2005), p. 1.6-6.</ref><ref name="N_17-8" /> | |||
== | Service crossings require their own protection. [[Firestopping]] addresses the paths around pipes, conduits, cables and ducts where they pass through the boundary. Personnel or vehicle openings require suitable closures within the arrangement described by Iqbal and Salley. The wall, penetration protection and closures form complementary parts of the separating system.<ref name="N_17-8" /><ref name="N_F-44">Iqbal and Salley (2004), p. F-44.</ref> | ||
Service support can also influence the wall's condition during collapse. NUREG-1805 describes routing pipes, conduits and cables near floor level to reduce the risk of damaging the wall when construction collapses on one side. This is a specific detailing consideration in that report. It illustrates why the location of a penetration can matter beyond its initial seal.<ref name="N_17-8" /> | |||
== Historical resistance examples == | |||
[[Fire resistance]] is established for an assembly and stated conditions, rather than assigned from a generic material name. NUREG-1805 nevertheless provides a table of historical rules of thumb for common wall constructions. The report labels these as typical estimates. They are useful examples of the influence of construction, but they are not current approvals for unspecified walls.<ref name="N_17-7" /><ref name="M_4-209_4-210" /> | |||
The table associates a 12-inch brick wall with a ten-hour estimate. It associates an 8-inch concrete-brick wall with six hours and a 16-inch nominal concrete-block wall with four hours. The corresponding nominal dimensions are approximately 305 mm, 203 mm and 406 mm. These conversions retain the original construction distinctions and do not create new tested specifications.<ref name="N_17-7" /> | |||
== | [[File:fse-fire-wall-v3.svg|thumb|upright=1.5|alt=Typical values: 12-inch brick 10 h, 8-inch concrete brick 6 h and 16-inch concrete block 4 h.|Typical wall fire-resistance examples from NUREG-1805. Based on Iqbal and Salley (2004), p. 17-7.]] | ||
The concrete-block row also distinguishes nominal from actual thickness. Its stated actual thickness is 15⅝ inches, approximately 397 mm, rather than the nominal 406 mm. That detail demonstrates why a rounded product description can differ from the tested or tabulated geometry. It also prevents the table from being read as a simple universal thickness-to-rating formula.<ref name="N_17-7" /> | |||
A contemporary application needs the evidence relevant to its actual wall and jurisdiction. Milke explains that test-based correlations remain limited by the conditions represented in their supporting tests. An old tabulated estimate does not independently resolve changes in loading, support or construction. The estimate and a verified rating are therefore different forms of evidence.<ref name="M_4-209_4-210" /><ref name="N_17-7" /> | |||
== Internal and external fire spread == | |||
A wall can address separation within one building and contribute to limiting [[Fire spread between buildings]]. The routes differ because external exposure can involve radiation, projecting flames and burning debris. The International Fire Engineering Guidelines treat these mechanisms explicitly. The adjacent building's openings and combustible surfaces are part of that assessment.<ref name="IFEG_1.6-5_1.6-7">Australian Building Codes Board et al. (2005), pp. 1.6-5–1.6-7.</ref> | |||
Radiation can expose material through glazing without the glass first falling out. A broken window can also change both the outgoing fire exposure and ventilation into the room. The guidelines therefore connect opening events to the fire-development analysis. A fire wall assessment cannot represent every external route solely through the temperature of the wall surface.<ref name="IFEG_1.6-7" /> | |||
The relative positions of boundaries and openings determine which routes require consideration. Vertical shafts and concealed spaces can connect different levels, while openings can connect neighbouring enclosures horizontally. The guidelines treat those connected spaces as enclosures within the analysis. The wall's function is therefore evaluated within a network of possible paths.<ref name="IFEG_1.6-6" /> | |||
Fire-separating and smoke-separating performance also differ. Klote describes smoke movement through construction cracks under pressure differences. An intact wall can consequently restrict flames while permitting some gas leakage. Where the strategy assigns a smoke-control function, the pressure and leakage conditions require attention alongside fire endurance.<ref name="Kl_4-277_4-278">Klote (2002), pp. 4-277–4-278.</ref> | |||
== Testing, installation and continued condition == | |||
A standard test represents a specified wall construction, load and support arrangement. Milke describes practical furnace and specimen constraints that limit direct reproduction of whole buildings. The result provides evidence for the assembly and permitted applications. Changes in the proposed wall therefore need to remain connected to the supporting test or calculation method.<ref name="M_4-209_4-211" /> | |||
= | New Zealand's C/VM2, second edition of 2025, gives one example of this connection in construction provisions. Details must match the developed design, while its commentary links penetration protection to the relevant orientation and separating element. These are requirements within that method. They do not convert a historical United States wall estimate into a New Zealand classification.<ref name="CVM_13">Ministry of Business, Innovation and Employment (2025), p. 13.</ref> | ||
The International Fire Engineering Guidelines identify barrier integrity and conformity with specifications as construction checks. They also note that passive features may be overlooked during later repairs and modifications. Continued identification of the wall's fire-safety role connects such work to the original strategy. This is particularly relevant where new openings or services alter its continuity.<ref name="IFEG_1.6-9">Australian Building Codes Board et al. (2005), p. 1.6-9.</ref> | |||
Inspection records concern the condition that exists, while the test or calculation describes the condition credited in the design. Both are needed to keep those descriptions aligned. The guidelines include documentation of maintenance requirements and recorded outcomes. They do not supply one universal inspection interval or wall detail for every application.<ref name="IFEG_1.6-9" /> | |||
== See also == | == See also == | ||
* [[ | * [[Passive fire protection]] | ||
* [[Fire | * [[Fire door]] | ||
* [[ | * [[Protected escape route]] | ||
== Notes == | == Notes == | ||
| Line 122: | Line 83: | ||
== References == | == References == | ||
* Australian Building Codes Board, National Research Council of Canada, International Code Council, & Department of Building and Housing New Zealand. (2005). ''International fire engineering guidelines'' | * Australian Building Codes Board, National Research Council of Canada, International Code Council, & Department of Building and Housing New Zealand. (2005). ''International fire engineering guidelines''. Australian Building Codes Board. | ||
* | * Iqbal, N., & Salley, M. H. (2004). ''Fire dynamics tools (FDTs): Quantitative fire hazard analysis methods for the U.S. Nuclear Regulatory Commission fire protection inspection program'' (NUREG-1805). U.S. Nuclear Regulatory Commission. | ||
* Kodur, V. K. R., & Harmathy, T. Z. (2002). Properties of building materials. In P. J. DiNenno (Ed.), ''SFPE handbook of fire protection engineering'' (3rd ed.). National Fire Protection Association. | * Klote, J. H. (2002). Smoke control. In P. J. DiNenno (Ed.), ''SFPE handbook of fire protection engineering'' (3rd ed., pp. 4-274–4-291). National Fire Protection Association. | ||
* Milke, J. A. (2002). Analytical methods for determining fire resistance of steel members. In P. J. DiNenno (Ed.), ''SFPE handbook of fire protection engineering'' (3rd ed.). National Fire Protection Association. | * Kodur, V. K. R., & Harmathy, T. Z. (2002). Properties of building materials. In P. J. DiNenno (Ed.), ''SFPE handbook of fire protection engineering'' (3rd ed., pp. 1-155–1-181). National Fire Protection Association. | ||
* Ministry of Business, Innovation and Employment. (2025). ''C protection from fire: Verification method C/VM2'' (2nd ed.) | * Milke, J. A. (2002). Analytical methods for determining fire resistance of steel members. In P. J. DiNenno (Ed.), ''SFPE handbook of fire protection engineering'' (3rd ed., pp. 4-209–4-238). National Fire Protection Association. | ||
* | * Ministry of Business, Innovation and Employment. (2025). ''C protection from fire: Verification method C/VM2'' (2nd ed.). | ||
* Van Rossum, E. (2027). ''Introduction to Fire Safety Engineering''. Fire Safety Academy. | |||
[[Category:Passive Fire Protection]] | [[Category:Passive Fire Protection]] | ||
Revision as of 19:14, 2 November 2026
A fire wall is a separating wall intended to restrict fire spread while maintaining the required resistance and structural stability. Its role combines the thermal and structural functions of building construction. In NUREG-1805's description of United States practice, a fire wall is distinguished from a barrier used alongside other protective measures.[1][2]
The complete separation includes the wall's supports, ends, roof junction and protected openings. Fire can pass around an otherwise effective wall or through a damaged penetration. Some fire walls are designed to remain stable after construction collapses on either side, but that capability must be part of the stated design.[3][4]
A fire-resistance duration alone does not describe all these conditions. The construction, exposure, support and required endpoints determine what the evidence demonstrates. Wall terminology and detailing provisions also differ between regulatory frameworks. Historical examples therefore need their document and jurisdictional context to remain explicit.[5][2]
Fire wall and fire barrier terminology
NUREG-1805 distinguishes two related forms of separating construction in its discussion of United States practice. A fire wall separates buildings or subdivides a building while providing resistance and structural stability. A fire barrier restricts spread and extends to the floor or roof deck above. The distinction follows the report's description of NFPA 221.[2]
The same account differentiates the assumed fire conditions. The fire wall is intended to remain stable during an uncontrolled fire without effective sprinkler protection. The barrier is considered alongside other protective measures, such as sprinklers. This identifies the performance basis within that framework rather than making the terminology universal across countries.[2]
Both constructions can contribute to Fire compartmentation, but their structural assumptions can differ. A wall's label does not independently explain whether surrounding construction may fail while the wall remains standing. That condition needs to be part of the design basis. Iqbal and Salley state that some fire walls are specifically designed to survive collapse on either side.[6]
A time rating is also a different description from structural independence. The rating concerns specified performance under a defined exposure. Independence concerns the relationship between the wall and the structures around it. A design needs evidence for whichever combination of those functions it claims.[1][7][3]
Heat transmission, openings and stability
Fire resistance criteria distinguish structural adequacy, integrity and insulation where those functions apply. Heat can pass through a wall even if the wall remains standing and has no opening. Cracks can permit gases or flames to pass before widespread collapse. These different mechanisms cannot be represented by observing only whether the wall is visibly upright.[1][8]
The insulation function depends on heat transfer through the construction. A thick material can develop a hot exposed surface while its interior remains cooler. Conductivity, heat capacity and exposure duration affect this temperature distribution. A description of noncombustibility does not by itself establish how long the unexposed surface remains within a specified limit.[9][10]
Integrity concerns routes through the wall. Openings may be present initially or develop through damage, cracking or failed protection around services. The International Fire Engineering Guidelines consider these routes separately from conduction through intact material. The neighbouring fuel and its exposure determine whether passage through a route develops into another fire.[11]
Stability includes the wall and any structural support it relies on. The guidelines note that a barrier may fail when its supporting member fails. They also require consideration of the effects on other barriers after structural failure. A separate wall rating cannot remove this dependency from the assembled building.[12]
Continuity at roofs, ends and penetrations
A wall can be bypassed at its edges even if the main surface performs as intended. Iqbal and Salley describe exterior wing walls at the ends of fire walls to restrict spread around them. They also describe a parapet continuing through and above the roof. These are examples of completing the separation in their United States technical context.[3]
The roof junction can otherwise connect the spaces on either side of the wall. The 2005 International Fire Engineering Guidelines identify concealed roof and ceiling spaces as possible routes between enclosures. A separating line in an occupied room does not automatically close those spaces. The boundary must be understood through its full extent and connections.[13][3]
Service crossings require their own protection. Firestopping addresses the paths around pipes, conduits, cables and ducts where they pass through the boundary. Personnel or vehicle openings require suitable closures within the arrangement described by Iqbal and Salley. The wall, penetration protection and closures form complementary parts of the separating system.[3][14]
Service support can also influence the wall's condition during collapse. NUREG-1805 describes routing pipes, conduits and cables near floor level to reduce the risk of damaging the wall when construction collapses on one side. This is a specific detailing consideration in that report. It illustrates why the location of a penetration can matter beyond its initial seal.[3]
Historical resistance examples
Fire resistance is established for an assembly and stated conditions, rather than assigned from a generic material name. NUREG-1805 nevertheless provides a table of historical rules of thumb for common wall constructions. The report labels these as typical estimates. They are useful examples of the influence of construction, but they are not current approvals for unspecified walls.[2][7]
The table associates a 12-inch brick wall with a ten-hour estimate. It associates an 8-inch concrete-brick wall with six hours and a 16-inch nominal concrete-block wall with four hours. The corresponding nominal dimensions are approximately 305 mm, 203 mm and 406 mm. These conversions retain the original construction distinctions and do not create new tested specifications.[2]
The concrete-block row also distinguishes nominal from actual thickness. Its stated actual thickness is 15⅝ inches, approximately 397 mm, rather than the nominal 406 mm. That detail demonstrates why a rounded product description can differ from the tested or tabulated geometry. It also prevents the table from being read as a simple universal thickness-to-rating formula.[2]
A contemporary application needs the evidence relevant to its actual wall and jurisdiction. Milke explains that test-based correlations remain limited by the conditions represented in their supporting tests. An old tabulated estimate does not independently resolve changes in loading, support or construction. The estimate and a verified rating are therefore different forms of evidence.[7][2]
Internal and external fire spread
A wall can address separation within one building and contribute to limiting Fire spread between buildings. The routes differ because external exposure can involve radiation, projecting flames and burning debris. The International Fire Engineering Guidelines treat these mechanisms explicitly. The adjacent building's openings and combustible surfaces are part of that assessment.[15]
Radiation can expose material through glazing without the glass first falling out. A broken window can also change both the outgoing fire exposure and ventilation into the room. The guidelines therefore connect opening events to the fire-development analysis. A fire wall assessment cannot represent every external route solely through the temperature of the wall surface.[8]
The relative positions of boundaries and openings determine which routes require consideration. Vertical shafts and concealed spaces can connect different levels, while openings can connect neighbouring enclosures horizontally. The guidelines treat those connected spaces as enclosures within the analysis. The wall's function is therefore evaluated within a network of possible paths.[13]
Fire-separating and smoke-separating performance also differ. Klote describes smoke movement through construction cracks under pressure differences. An intact wall can consequently restrict flames while permitting some gas leakage. Where the strategy assigns a smoke-control function, the pressure and leakage conditions require attention alongside fire endurance.[16]
Testing, installation and continued condition
A standard test represents a specified wall construction, load and support arrangement. Milke describes practical furnace and specimen constraints that limit direct reproduction of whole buildings. The result provides evidence for the assembly and permitted applications. Changes in the proposed wall therefore need to remain connected to the supporting test or calculation method.[5]
New Zealand's C/VM2, second edition of 2025, gives one example of this connection in construction provisions. Details must match the developed design, while its commentary links penetration protection to the relevant orientation and separating element. These are requirements within that method. They do not convert a historical United States wall estimate into a New Zealand classification.[17]
The International Fire Engineering Guidelines identify barrier integrity and conformity with specifications as construction checks. They also note that passive features may be overlooked during later repairs and modifications. Continued identification of the wall's fire-safety role connects such work to the original strategy. This is particularly relevant where new openings or services alter its continuity.[18]
Inspection records concern the condition that exists, while the test or calculation describes the condition credited in the design. Both are needed to keep those descriptions aligned. The guidelines include documentation of maintenance requirements and recorded outcomes. They do not supply one universal inspection interval or wall detail for every application.[18]
See also
Notes
- ↑ 1.0 1.1 1.2 Kodur and Harmathy (2002), p. 1-155.
- ↑ 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 Iqbal and Salley (2004), p. 17-7.
- ↑ 3.0 3.1 3.2 3.3 3.4 3.5 Iqbal and Salley (2004), p. 17-8.
- ↑ Australian Building Codes Board et al. (2005), pp. 1.6-6–1.6-8.
- ↑ 5.0 5.1 Milke (2002), pp. 4-209–4-211.
- ↑ Iqbal and Salley (2004), pp. 17-7–17-8.
- ↑ 7.0 7.1 7.2 Milke (2002), pp. 4-209–4-210.
- ↑ 8.0 8.1 Australian Building Codes Board et al. (2005), p. 1.6-7.
- ↑ Van Rossum (2027), §5.2.
- ↑ Milke (2002), pp. 4-210–4-211.
- ↑ Australian Building Codes Board et al. (2005), pp. 1.6-6–1.6-7.
- ↑ Australian Building Codes Board et al. (2005), p. 1.6-8.
- ↑ 13.0 13.1 Australian Building Codes Board et al. (2005), p. 1.6-6.
- ↑ Iqbal and Salley (2004), p. F-44.
- ↑ Australian Building Codes Board et al. (2005), pp. 1.6-5–1.6-7.
- ↑ Klote (2002), pp. 4-277–4-278.
- ↑ Ministry of Business, Innovation and Employment (2025), p. 13.
- ↑ 18.0 18.1 Australian Building Codes Board et al. (2005), p. 1.6-9.
References
- Australian Building Codes Board, National Research Council of Canada, International Code Council, & Department of Building and Housing New Zealand. (2005). International fire engineering guidelines. Australian Building Codes Board.
- Iqbal, N., & Salley, M. H. (2004). Fire dynamics tools (FDTs): Quantitative fire hazard analysis methods for the U.S. Nuclear Regulatory Commission fire protection inspection program (NUREG-1805). U.S. Nuclear Regulatory Commission.
- Klote, J. H. (2002). Smoke control. In P. J. DiNenno (Ed.), SFPE handbook of fire protection engineering (3rd ed., pp. 4-274–4-291). National Fire Protection Association.
- Kodur, V. K. R., & Harmathy, T. Z. (2002). Properties of building materials. In P. J. DiNenno (Ed.), SFPE handbook of fire protection engineering (3rd ed., pp. 1-155–1-181). National Fire Protection Association.
- Milke, J. A. (2002). Analytical methods for determining fire resistance of steel members. In P. J. DiNenno (Ed.), SFPE handbook of fire protection engineering (3rd ed., pp. 4-209–4-238). National Fire Protection Association.
- Ministry of Business, Innovation and Employment. (2025). C protection from fire: Verification method C/VM2 (2nd ed.).
- Van Rossum, E. (2027). Introduction to Fire Safety Engineering. Fire Safety Academy.