Fire-Resistive Construction: Fire Walls, Fire Barriers and Fire Partitions
Fire-resistive construction involves the use of passive means to provide fire resistivity
to specific elements of the building that require additional protection in a fire. Fire
protection by passive means is the use of walls and floors constructed of fire
resistive materials, opening protections, and penetration protection assemblies to prevent
the passage of heat, fire and smoke for a specific time period without the use of active
measures such as automatic fire sprinkler systems.
Fire resistive walls can be classified into three different types of assemblies to resist
fire: fire walls,
and fire partitions.
Each of these types have an increasing level of protection, with fire walls providing the greatest protection.
[BF] FIRE WALL. A fire-resistance-rated
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
Fire walls provide protection of one building or portion of a building for the condition
where the building on the other side is fully engulfed in flames and could be subject to
complete collapse. The concept originated in densely populated urban areas where
buildings were built directly against lot lines, which is used to this day.
Fire walls, covered in
use a number of methods to provide this highest level of fire protection. They use
parapets, fire wall extensions beyond the face of the building, and higher
as compared to other types of fire assemblies. Fire walls more strictly limit openings
allowed and are typically constructed out of non-combustible materials, unless the
type of construction
of the building is Type V.
A primary feature of fire walls not found in other fire-resistive walls is the requirement
that the wall be designed with the structural stability to allow collapse of the structure
on either side without collapse of the wall itself under fire conditions. Fire walls
constructed in accordance with NFPA 221, which is a standard by the National Fire
Protection Association for fire walls, are considered to meet this standard. However, it
should be pointed out that the building code does not require construction in accordance
with NFPA 221 to be a proper fire wall. NFPA 221 provides a number of requirements beyond
what the building code specifies. However, a design for proper structural stability
should take into account a number of factors that NFPA 221 recognizes. These include:
stability under applied design loadings including applicable out-of-plane loadings
stability due to forces from the collapse of the adjacent structure, including
pulling away of materials, decking or the collapse of items such as storage racks
onto the wall during a fire
stability and integrity of the wall due to expansion of materials during the fire
due to heat
consideration of the 5psf out of plane loading under typical conditions
Fire ratings of walls are based on the adjacent occupancies found adjacent to the wall.
In addition, the ratings of fire walls should be checked against
for fire walls adjacent to lot lines. In addition, specific fire ratings are required for
any openings in fire walls, such as those found in
based on the fire rating (in hours) of the wall itself.
Construction of fire barriers can be either non-combustible or combustible construction in
accordance with the type of construction of the building.
Supporting construction (such
as beams or other structural floor systems) is required to be equal to the fire-resistance
rating of the fire barrier supported. There are exceptions for incidental uses and walls
separating tank storage. If a concrete slab or other member is used for support of walls,
the architect should review
and coordinate with the structural engineer to ensure the properly sized member or proper
concrete cover for slab reinforcement or tendons (in post-tension construction) is
provided for the hour rating required for the fire barrier.
Fire barriers provide a more generous allowance for openings in walls than do fire walls.
However, there are a number of restrictions and requirements for openings in fire
barriers. Membrane penetrations, through penetrations, joints at intersections of fire
rated assemblies and floor or roof/ceiling assemblies, fire doors and fire window
assemblies all have specific requirements depending on the use of the fire barrier and the
type of item used. For example, fire-resistance rated glazing tested in accordance with
ASTM E119 or UL 263 does not have to meet the requirements for fire protection glazing
because it meets the requirements of a wall, but fire protection glazing tested in
accordance with NFPA 257 or UL 9 shall meet the requirements of
for glazing. Because each item in a fire barrier is a potential point of weakness, and
just a small failure can have catastrophic results, it is important to dig into each
requirement to ensure that the minimum requirements of the code are met or exceeded.
These are recognized as being so critical, that special inspections are required per
Section 1705.17 in high-rise buildings and those buildings of Risk Category III or IV for
membrane penetration firestops,
fire-resistant joint systems
and perimeter fire barrier systems. Also, for fire barriers or any fire-resistant
construction, when there is an accessible concealed floor, attic space or other space
where maintenance or other trades could install unprotected penetrations in the wall, a
stencil identifying the wall as such is required per
If Fire Barriers are used to separate the building into
UpCodes Code Calculators will show the required ratings for such fire barriers in
Table 707.3.10 based on occupancy groups provided.
Fire barriers provide the most basic level of protection against fire. They are used to
separate dwelling units, tenant spaces in mall buildings, corridor walls, elevator lobby
separations and egress balconies. Fire partitions may be of any material permitted by the
building type of construction, and typically have a fire-resistance rating of 1 hour.
However, dwelling or sleeping unit separations in Buildings of Type IIB, IIIB and VB
construction may have ½ hour fire-resistance ratings when an NFPA 13 automatic sprinkler
system is installed.
Fire barriers are continuous from the floor/ceiling assembly below and extend to either
the underside of the roof or floor sheathing or deck above, or to the underside of a floor
or roof/ceiling assembly having at least the same fire rating as the assembly itself.
There are specific exceptions for corridor walls to allow for what is commonly called
Tunnel construction allows for the ceiling membrane of the corridor to be equivalent to
the corridor wall membrane. This is allowed provided that the room side membrane extends
to the underside of the floor or roof sheathing, or the building is equipped with an NFPA
13 or 13R automatic sprinkler system and sprinklers are installed between the top of the
fire partition and the underside of the roof or floor sheathing or deck above.
Alternatively, tunnel construction with both a lower and upper membrane matching the wall
construction is allowed where the corridor ceiling assembly matches the corridor wall
assembly. Wall assemblies can be found in
which shows the prescribed assembly in which to obtain various fire ratings ranging from
one to four hours.
Supporting construction for fire partitions such as beams, columns or floor joist
assemblies shall have a rating to match the rating of the wall. However, this does not
apply to buildings of Type IIB, IIIB and VB construction, since such a requirement would
have the effect of making a great deal of the building fire resistant construction,
contrary to the non-rated nature of Type IIB, IIIB and VB construction.
UpCodes Code Calculators can help determine the fire-resistance rating requirement for
corridor walls based on the sprinkler system and the occupancies that are designated as
being served by the corridor.
UpCodes Code Calculators
UpCodes Code Calculators provide powerful tools to be able to determine a number of code
requirements rapidly. They also provide the ability to adjust parameters quickly to
discover how compliance with code requirements change as a project changes. Other
features include allowable area and height calculators, egress calculations with
cumulative loading features and exporting code sheets for use in your construction
documents. These code reports are exported to an excel spreadsheet that will provide all
generated code information in an easy to understand format for use in your construction
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Please note we’ve used the Wyoming Building Code for the examples above as it shares much in common with many other state and city codes. Please reference your jurisdiction’s codes for amendments specific to your project.