Nfpa 221 1997
Nfpa 221 1997
Nfpa 221 1997
GAP.2.2.1
POSITION
Definitions
Fire Walls
Global Asset Protection Services (GAPS) further classifies three types of fire walls. A standard fire
wall is a blank, parapeted, non-load bearing (freestanding, double, or tied firewalls), masonry fire wall
constructed of material with at least a 4 h fire resistance rating. A MFL wall is a parapeted, non-load
bearing, fire wall constructed of materials with at least a 4 h fire resistive rating. A fire wall is a
parapeted wall, constructed of material with at least a 3 h fire resistance rating. Protect openings in
the MFL fire wall and the fire wall with equivalent fire resistant rated materials/assemblies. Protected
columns within the tied and double fire walls can carry the gravity load. All masonry wall material
should be non-load bearing.
Global Asset Protection Services LLC and its affiliated organizations provide loss prevention surveys and other risk management, business continuity and facility asset
management services. Unless otherwise stated in writing, our personnel, publications, services, and surveys do not address life safety or third party liability issues. The
provision of any service is not meant to imply that every possible hazard has been identified at a facility or that no other hazards exist. Global Asset Protection Services LLC
and its affiliated organizations do not assume, and shall have no liability for the control, correction, continuation or modification of any existing conditions or operations. We
specifically disclaim any warranty or representation that compliance with any advice or recommendation in any document or other communication will make a facility or
operation safe or healthful, or put it in compliance with any law, rule or regulation. If there are any questions concerning any recommendations, or if you have alternative
solutions, please contact us.
GAP.2.2.1
Fire Barriers
Fire barriers have from 2 h 3 h fire resistance. The wall extends from the floor to the bottom side of
the roof or floor deck, or from the floor to a fire resistance rated floor-ceiling assembly of equal fire
rating.
Fire Partitions
Fire partitions have from 1 h 2 h fire resistance, extend from the floor to the ceiling, but in all other
respects are similar to fire barriers.
Design Features
Construct fire walls, fire barriers and fire partitions with material that has been tested and rated in
accordance with ASTM E 119, ISO 834-1, EN 1363-1, or AS/NZ 1530.
Concrete walls constructed with various aggregates have already been tested. Figure 1 shows the
fire resistance rating of concrete walls constructed with various aggregates at various thicknesses.
Design fire walls as freestanding, tied or double fire walls. The fire wall must:
Be designed as nonloadbearing. The structural framing in a tied fire wall can be loadbearing;
however, the wall material must not carry any loads.
Be constructed with Type M or S mortar using full bed mortaring when concrete blocks are used.
Type M mortar contains no more than 1 part Portland cement, not over 25% hydrated lime or lime
putty (by cement volume) and not less than 2!/4 and not more than 3!/2 parts clean sand. Type S
mortar contains no more than 1 part Portland cement, not less 25% and not more than 50%
hydrated lime or lime putty (by cement volume) and not less than 2!/4 and not more than 3!/2 parts
clean sand.
Be designed, constructed and maintained with all openings protected with listed
through-penetration systems, fire dampers or fire doors.
Be designed, constructed and maintained with minimal amount of openings. The aggregate width
of the openings must not exceed 25% of the total wall length.
GAPS Guidelines
2
GAP.2.2.1
Be designed for a minimum uniform load of 5 psf (0.24 kPa) from either direction applied
perpendicular to the face of the wall. Design the wall and parapet for wind loading in accordance
1
with local building design standards and GAP.2.0.1.1. In areas prone to earthquakes, design for
2
earthquake loading in accordance with local building design standards and GAP.2.0.9. Submit
drawings and calculations with a registered civil/structural engineers stamp to the local GAPS
Plan Review Office.
Be designed and constructed to remain stable after collapse of the structure on either side of the
wall or expansion or collapse of material stored near the wall.
Be constructed with expansion, seismic and control joints a maximum every 150 ft (45 m). Have
joints filled with listed joint treatment systems.
Be designed with clearances per NFPA 221, between freestanding wall and structural framework
on either side, between tied walls and roof beams and girders, and between double walls.
Have extension walls, end walls, angle walls in accordance with NFPA 221.
Extend from exterior wall to exterior wall or from one standard fire wall to another standard fire
wall.
Extend continuously through all stories of the building, and through the roof to form a minimum 3 ft
(0.9 m) parapet over the highest elevation.
Fire barriers and fire partitions do not require parapets, end walls or angle walls, and can be
loadbearing. Fire barriers and fire partitions must:
Be designed for a minimum uniform load of 5 psf (0.24 kPa) from either direction applied
perpendicular to the face of the wall;
GAPS Guidelines
3
GAP.2.2.1
Reinforce the horizontal joints in concrete block walls immediately above and below the sleeve.
Position pipes and conduits passing through the wall no closer than three times the largest pipe or
conduit diameter.
Design and install all piping, wiring or cable trays penetrating fire walls no more than 3 ft (0.9 m) from
the floor. If the structural framework, including joists, beams and girders, has a fire resistance equal to
that of the wall, the penetration may be at any level in the wall.
Design and install ductwork with two listed, 3 h fire resistance rated, fire dampers one on each side of
a 4 h fire wall. Provide slip joints between the ductwork and the damper sleeve.
More detailed information on opening protection, maintenance and testing is found in NFPA 80 and
GAP.2.2.2.
DISCUSSION
Wall openings
Openings are the greatest weaknesses of fire walls. Every opening increases the possibility of fire
spreading beyond or through the wall. No fire wall, regardless of its fire rating, will reliably protect
against fire spread if openings are unprotected or the opening protection is poorly maintained.
A fire wall should be considered the last line of defense against fire spread. Only when automatic
sprinklers are not effective in controlling a fire will the fire wall is needed. If sprinklers are impaired or
otherwise rendered ineffective, waterspray will be similarly affected. For this reason, GAPS does not
recommend waterspray for opening protection.
Parapet
The fire wall must extend from the floor through the roof to form a parapet. A parapet tops off the fire
wall as an extension of it above the roof line and prevents a roof fire from spreading across the fire
wall. Generally, parapet height should be at least 30 in. (0.76 m) above the highest roof or structure
within 25 ft (7.6 m) of the fire wall.
Extension Wall
An extension wall is an extension of the fire wall beyond the exterior wall where the exterior and fire
walls meet. An extension wall may be substituted for an end wall. (Refer to Figure 4.)
End Wall
An end wall (or wing wall) is a blank masonry exterior wall that meets an interior fire wall at right
angles to form a T-shaped juncture. End walls may be required if the exterior walls could fail early in
GAPS Guidelines
4
GAP.2.2.1
the fire due to their combustibility or method of securement to the building structure. They are
designed to prevent the fire from passing around or through the walls. The length of the end wall
depends on the wall height. See NFPA 221 for the specific requirements. (Refer to Figure 4.)
Angle Wall
Where the two exterior walls of two buildings meet to form an L-shaped juncture at the interior fire
wall, construct an angle wall, consisting of a blank wall rated at most 1 h less than the fire wall.
Extend the angle wall from the juncture out the required distance to prevent angle exposure. In
addition, construct the exterior wall from the end of the angle wall out the required distance of
noncombustible material. The length of the angle wall depends on the occupancy. See NFPA 221 for
the specific requirements (Refer to Figure 4.)
GAPS Guidelines
5
GAP.2.2.1
A tied fire wall is a wall erected to encase the steel framing or tied to the steel framing that is coated
with a fireproofing material. The wall is held in place by the steel columns that support the roof
system. (Refer to Figure 7). To maintain its stability, the roof steel on either side must be strong
enough to resist forces caused by steel collapsing on a fire-exposed side. This stability is usually
accomplished by having through-ties attached to the web on the beams and pass through the wall.
A double one-way fire wall consists of two one-way walls back-to-back with a separation between
them. The separation distance is based on NFPA 221. Each wall must have at least 3 h fire
resistance (Refer to Figure 8.) The double fire wall is more commonly found in new construction
where a fire wall between an existing structure and a new building is required. The existing wall,
secured to the existing building frame, could be upgraded to the required fire resistance rating. Then
the new rated fire wall could be raised next to it and secured to the new building frame. If a fire on
one side of the wall causes the loss of one wall, the wall supported by the other side should remain
standing.
Nonrated metal panel walls can be reinforced by adding listed 3 h fire rated metal panels. Tilt-up
concrete and masonry walls can usually be reinforced to provide a specified fire resistance rating.
GAPS Guidelines
6
GAP.2.2.1
GAPS Guidelines
7
GAP.2.2.1
A one-way fire barrier, the simplest of the fire barriers, is designed to withstand a fire on one side
only. It is effective for separating a high value occupancy with low combustible loading from a higher
hazard occupancy, and is tied into the steel or other framework on the low hazard side.
A one-way fire barrier should be a nonloadbearing wall:
Installed to follow the column line so it can benefit from the vertical strength of the column and
resist twisting forces as much as possible. All columns and trusses parallel to and within 1 ft
(0.3 m) of the barrier should have the same fire resistance rating as the barrier.
When building bays on either side of the barrier have unequal strength, the lateral resistance of the
frame on either side must resist horizontal forces.
Where two buildings are joined with a barrier or where the same building is separated into two
sections by a barrier, each side of the building must be balanced for stability. The barrier should be
tied to its framing at the same level on both sides, and the columns should be located and reinforced
so that the symmetry of the building is not distorted. There must be sufficient lateral resistance of the
continuous steel frame on either side of the barrier to resist horizontal forces on either side.
Horizontal forces should be calculated by a licensed professional engineer.
REFERENCES
1.
ASCE 7, Minimum Design Loads For Buildings And Other Structures, American Society of Civil Engineers, Reston, VA.
AS 1170.4 Structural Design Actions Part 4: Earthquake Loads, Standards Australia, Sydney, Australia
AS/NZS 1170.2 Structural Design Actions Part 2: Wind Actions, Standards Australia, Sydney, AS
NZS 1170 Part 5: Earthquake Actions, Council of Standards New Zealand
EN 1998-1 Design of Structures for Earthquake Resistance-Part 1: General Rules, Seismic Actions And Rules For
Buildings, European Committee For Standardization, Brussels, Belgium
GAPS Guidelines
8
GAP.2.2.1
REFERENCES (Contd)
EN 1991-1-4 - Eurocode 1: Actions On Structures - Part 1-4: Wind Actions, European Committee For Standardization,
Brussels, Belgium
NBCC - National Building Code of Canada, National Research Council of Canada, Ottawa, Canada
GB50009 - China National Standard, China Architecture and Building Press, Baiwanzhuang, Beijing, China
GB50011 Code for Seismic Design of Buildings, China Architecture and Building Press, Baiwanzhuang, Beijing, China
CP-2004 - Code of Practice of Wind Effects, Building Department Hong Kong
IS 875 (Part 3) - Indian Standard Code of Practice, Bureau of Indian Standards, New Delhi, India
IS:1893 Indian Standards Criteria for Earthquake Resistant Design of Structures, Bureau of Indian Standards, New Delhi,
India
SNI-03-1727 - Standard National Indonesia, Indonesia
AIJ-RLB - Recommendations For Loads On Buildings, Architectural Institute of Japan, Tokyo, Japan
KGG KBC 2005 -Korean Government Guidelines of Korean Building Code, Korea
MS1553 -Code of Practice of Wind Loading, Malaysia Standard, Malaysia
NSCP - National Structural Code of the Philippines, Association of Structural Engineers of the Philippines, Manila,
Philippines Philippines
EIT-1018-46 Wind Loading Code for Building Design, Engineering Institute of Thailand,
TCVN2737 Loads and Actions Norn for Design, Vietnam
2
ASCE 7, Minimum Design Loads For Buildings And Other Structures, American Society of Civil Engineers, Reston, VA.
AS 1170.4 Structural Design Actions Part 4: Earthquake Loads,Standards Australia, Sydney, Australia Australia
NZS 1170 Part 5: Earthquake Actions, Council of Standards New Zealand
EN 1998-1 Design of Structures for Earthquake Resistance-Part 1: General Rules, Seismic Actions And Rules For
Buildings, European Committee For Standardization, Brussels, Belgium Europe
GB50011 Code for Seismic Design of Buildings, China Architecture and Building Press, Baiwanzhuang, Beijing, China
IS:1893 Indian Standards Criteria for Earthquake Resistant Design of Structures, Bureau of Indian Standards, New Delhi,
India
AIJ-RLB - Recommendations For Loads On Buildings, Architectural Institute of Japan, Tokyo, Japan
NBCC - National Building Code of Canada, National Research Council of Canada, Ottawa, Canada
GAPS Guidelines
9